PAKISTAN SCIENCE CONFERENCE PEAHAWAR 17- 22 MARCH 1952 FLEAS AND THE PART THEY PLAY IN PLAGUE

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP83-00423R001300270004-4
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 49
• Document Creation Date: November 9, 2016
• Document Release Date: March 17, 1999
• Sequence Number: 4
• Publication Date: March 1, 1952
• Content Type: REPORT

CPYRGHT
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
262 Nutritional requirements of flea larvae
the human population subsists on imported polished
rice (Hirst, 1933, pp. 93-4), X. cheopis is mostly
found on this rat. The fact that in Colombo (Hirst,
1927a, p. 346), whore the domestic rats in the resi-
dential areas are exclusively parasitized by X. astia,
X. cheopis is found on rats in the mercantile premises
where piece goods, hardware and dry goods are
stored, suggests that wherever a poor larval diet
is available in the nest of the domestic rat only
X. cheopis can thrive.
The fact that the larvae of the three Indian species
of rat-fleas can develop on proteins other than those
of blood (see p. 255) along with vitamins of the
B group is of great significance, as it ensures their
fairly wide dispersal. The fact that larvae of
X. cheopis and X. brasiliensis develop on wheat flour
alone better than those of X. astia (Tables 1, 2)
affords the first two species better opportunities of
establishing themselves when transported with grain
far from their original home. It is possibly for this
reason that these species have an almost world-wide
distribution (Buxton, 1941, pp. 119, 121), and are
found in places wherever the environmental condi-
tions are favourable for their breeding. X. cheopis,
whose original home appears to be the Mediter-
ranean subregion, has extended to moderately cold
regions almost all over the world, and has been
recorded from places between 40? N. and 40? S.
(Sharif, 1930, p. 47). X. brasiliensis, which is the
second most widely distributed species of the genus
(Hirst, 1927 a, p. 283), having its ancestral home in
the plateaux of the Ethiopian region and perhaps of
the Ceylonese subregion, has spread to the table-
lands of Peninsular India and the seaboard of the
continent of America. On the other hand, a com-
paratively poor growth of the larvae of X. astia on
wheat flour even in the presence of a slight fungous
growth which is only possible at relative humidities
higher than 70% (Fraenkel & Blowett, 1943b,
p. 467), militates against a very wide dispersal of this
species through the grain trade in the absence of its
hosts. Consequently, X. astia has a restricted distri-
bution, confined to the lowlands of the southern
Asiatic countries (Hirst, 1926, p. 162), and has not
been able to establish itself on rodents of countries
far from its original home, even though their climatic
conditions may be favourable. Its ancestral home is
the Indo-Chinese subregion, and perhaps the Indian
and Ceylonese subregions, as it is preponderantly
found on their wild rodents.
VII. SUMMARY
The comparative nutritive value of dried horse
blood, highly milled wheat flour devoid of bran,
a mixed diet of blood and wheat flour and that of
blood and yeast for the larvae of Xenopsylla cheopis,
X. brasiliensis and X. astia was ascertained experi-
mentally. Pure blood proved inadequate, probably
because it is deficient in accessory food factors.
The growth of their larvae on wheat flour alone
was erratic; only partial success was obtained,
and the adults emerged after long and irregular
intervals. This I attribute to the association of
micro-organisms, possibly fungi, with this food.
A mixture of blood and wheat flour quickened their
larval development, but it was not a satisfactory
larval diet. Blood and yeast form an ideal food for
all flea larvae.
It is concluded that larval diets,-containing blood
or wheat proteins and vitamins of the B group, are
essential for the successful rearing of these rat-fleas,
and that the proper sclerotization of the adult is due
to the presence of haemoglobin in the larval food.
The available data on the effects of diverse diets on
the growth of flea larvae lend strong support to the
conclusion that successful development depends on
the presence of these vitamins in the food; it also
loads me to think that their source in nature may be
the association of micro-organisms with the food.
The larval food appears to be an important factor
that governs the distribution and host preferences of
different species of flea. The larvae of X. astia require
the most nutritive diet. If a rich larval food is
present in a rodent burrow, X. astia flourishes, as in
the burrows of Tatera indica and Bandicota mala-
barica, and even in those of the domestic rats in
certain regions. In contrast, the nutritional require-
ments of the larvae of Xenopsylla cheopis and
X. brasiliensis are simple ; thus they prosper readily
in a burrow of the domestic rat, even where the
nutritive value of the larval food is very low. As
the temperature tolerance of X. brasiliensis is the
lowest, this species is confined to some of the cooler
regions.
The irregular distribution of the three species of
rat-fleas inside India may be related to differences in
the nutritional value of the varied organic sub-
stances found in rat burrows in different places. The
fact that the distribution of X. cheopis and X. brasi-
liensis is wider than that of X. astia is attributed to
the ability of the larvae of the first two species to
grow better on flour alone; this possibly enables
them to survive transport in grain, even without rats,
to places far from their original home.
I am much indebted to my, chief, Lt.-Col. Sir
Sahib Singh Sokhey, Director, Haffkine Institute,
Bombay, for affording me many facilities for the
pursuit of these investigations, and for his en-
couragement and advice. Prof. P. A. Buxton, F.R.S.,
has kindly read through and revised my manuscript
and made many valuable suggestions, for which I am
obliged to him. I am also obliged to Sir John Taylor
for going through the manuscript.
I take this opportunity of acknowledging my
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 W)(@ eldfor Release 1999/09/10: CIA-RDP83-00423R001300270004-4
Sorghum (Andropogon sorghum), spiked millet
(Pennisetum typhoideum) and cotton are the main
agricultural products of these regions. Cattle fodder
is mostly the dried stalks of the two millets, which
are stored,in stacks in the backyards of houses, and
are often utilized by domestic rats to build their
nests. The nesting conditions of domestic rats in
these regions provide such a poor diet for flea larvae
that only Xenopsylla cheopis can prosper.
The primary factor affecting the distribution of X.
brasiliensis is temperature, as the upper temperature
limit of its larval development is lower than those
of two other species (Sharif, 1948). As mentioned
before (see p. 255), its larvae developed best ona diet
composed exclusively of wheat flour, which suggests
that the' vitamin B requirements of the larvae of
this spocies are the lowest. Consequently, this flea
mostly abounds in grain stores of cooler places, such
as Mysore City, Davanageo, Sagar, Shimoga in the
Mysore State (Iyer, 1933, pp. 984-93). This species
appears to be common only in the predominantly
millet- and rice-growing cooler elevated tablelands
of Peninsular India. On the watersheds of the
Western Ghats in the Dharwar taluk, it was often
found in big commercial towns, but not in the
adjoining villages. Its tolerance of a low temperature
probably accounts for this disparity in the distribu-
tion. Granaries in big towns are well protected against
the sun, which is not the case in small villages.
X. brasiliensis is entirely absent in the lowlands of
Peninsular India. Its distribution is mainly re-
stricted. to the tablelands of Peninsular India and
Africa (Buxton, 1941, p. 121), and belts of plains
with high temperature have limited its dispersal.
Thus its distribution is controlled to a large extent
by climatic barriers and zoogeographical principles.
The larvae of X. astia are tolerant of a higher tem-
perature than those of the other 1' we species (Sharif,
1948). Patton & Evans (1929, p. 534) suggested that
the `optimum conditions for its life processes are
a somewhat higher temperature than cheopis and
a high atmospheric humidity'. The nutritional re-
quirements of the larvae of X. astia being higher
than those of the other two species, they require food
rich in vitamins of the B group, and possibly in pro-
teins also. Consequently, a higher water content in
the food may be needed so as to encourage growth
of fungus, which appears to be essential for their
development.
X. astia is the flea of domestic rats in rice-growing
warm and moist lowlands and plains of India
bordering the Bay of Bengal and those of Burma and
Ceylon (Hirst, 1927a, p. 326). Paddy (unhusked
rice) or its husks and straws stored in houses are
utilized by domestic rats for making nests. The husk
of the paddy is fairly rich in vitamins of the B group,
as the pericarp and a greater part of the embryo
remain attached to it after the polishing of rice, and
in humid and warm places fungus and other mic,o-
organisms can easily flourish on such a litter. Con-
sequently, being a stronger competitor in the strug, le
for existence than the other two species and able to
withstand higher temperature, X. astia prospers in it.
Some of the villages of the Dharwar taluk tl.at
produced a small quantity of wheat, in addition to
other cereals, had comparatively larger proportic ns
of X. astia on their domestic rats than those that c id
not. Possibly, there is some association between
wheat cultivation and this flea. McCarrison (1937,
p. 636) showed experimentally that of the four in-
portant Indian cereals, viz. wheat, spiked millet,
sorghum, paddy, the first has more nutritive valie,
both as regards proteins and vitamin B compb,x,
than the others. These cereals can influence the
different distribution of rat-fleas by providing lar? -al
food of different nutritive value in the burrows of
their hosts (see p..260). In the wheat-growing plans
of the Punjab and the United Provinces X. astio is
also found along with X. cheopis on domestic rats in
fairly large proportions (Hirst, 1927 a, pp. 380, 416),
and at some places even the former species p ?e-
dominates (Cragg, 1921, 1923). In thorn wheat chaff
and straw are utilized by domestic rats for making
their nests, as they are usually stored in houses, a ad
form the main fodder for cattle. Wheat straw a nd
chaff, when kept even in a moderately wet soil,
encourage growth of micro-organisms.
In view of this analysis of the burrow condition,- of
different rodents, it is reasonable to suggest that the
irregular distribution of the three species of rat-fle is,
especially that of X. cheopis and X. astia, in India
(see Hirst, 1927 a, p. 381) is governed by the nesting
conditions and nature of food of their hosts in co n-
bination with the climatic conditions. Wherever
debris and litter, containing larval food rich in
vitamins of the B group and perhaps in proteins, s.re
present in the burrow of a rodent, either as the res dt
of association of micro-organisms or owing to the
presence of substances intrinsically rich in then,
X. astia is the sole flea. Tb is presumption is supported
by the fact that domestic rats in the paddy-growi ag
districts in the warm and moist regions around the
Bay of Bengal, and Tatera indica and Bandies ata
malabarica in the Deccan Plateau are parasitized by
Xenopsylla astia. In contrast, if the debris and lit ,er
contain larval food with low concentration of those
nutriments, as is found in the burrows of the
domestic rats of comparatively warmer regions of
the Deccan Plateau, X. cheopis is exclusively fou:id
on them. It is possibly for these reasons that planes
in the plains of Bundelkhand (Hirst, 1927 a, pp. 3! 4,
399), the Madras Presidency (Hirst, 1925, p. 1)),
eastern Bengal, Assam and Burma (Hirst, 192, a,
p. 392), where the human population lives on boa ly
produced paddy, have X, astia as the preponderating
species on the domestic rat; but in those places why ire
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 CPYRGHT
Nutritional requirements of flea larvae
The distribution of the three Indian species of
Xenopsylla and their host preferences can logically be
explained on the basis of differences in the nutri-
tional requirements of their larvae. It seems that
the larvae of each of these species have certain
minimum nutritional requirements. If the food
available in a locality is lacking in any one of the
required nutritive constituents for the larvae of a
species, that insect will be absent. Fleas being
mostly inhabitants of the nests and retreats of their
hosts, their larvae are dependent upon the nutriment
found in them. Organic substances found in the
retreats of different rodents are variable (Sharif,
1948). Even in the domestic rat burrow, in addition
to flea faeces, the organic matter found, which con-
sists mostly of the nesting material and rat drop-
pings, is very variable in diverse localities, being
dependent on the agricultural products available.
Furthermore, its nutritive value both in quality and
quantity is greatly influenced by the prevailing
weather conditions in an area (see Shelford, 1930,
p. 101). If the burrow humidity is high, growth of
micro-organisms, especially mould, will set in, which
will enhance the nutritional value of the larval food.
Important articles of diet for rat-flea larvae in nature
are rat and flea faeces, but even the nutritive value of
the faeces of domestic rats varies in different places.
Undigested food particles are passed along with rat
faeces; at different places various kinds of crushed
grains and their husks, depending on the staple food
of the inhabitants of the locality, have been seen in
the faeces and stomach contents of rats.
The burrows of Tatera indica are very long and
tortuous ; they are also very deep, their depth varying
from 24 to 54 in. The water content of the soil in such
burrows must surely be high enough to encourage
fungous growth on debris; indeed, I have personally
seen moulds growing on the faecal pellets and nesting
material of this rodent. It is suggested that the
presence of fungus on the debris and litter of such
burrows plays an important part in the enormous
increase of the population of Xenopsylla astia in
them. Tatera indica usually lives in colonies com-
posed of 6-30 individuals in a complicated burrow
system. There can be nothing better for enormous
multiplication of Xenopsylla astia, as every neces-
sary food constituent for flea larvae is present. Con-
sequently, this flea is abundant in the burrows of
Tatera indica to the entire exclusion of others
throughout the year, and on a number of occasions
one to two thousand fleas were recovered from its
burrows.
Similarly, many individuals of Bandicota male-
barica live in a complicated and tortuous burrow
system, which is also very deep. The debris in it,
especially in the resting chambers, is fairly wet. As
a rule, this rodent does not build a nest; only a few
sparsely scattered grains, shells of groundnuts,
leaves, etc., in a fairly sodden state, with fungous
growth on them, were found in the chambers. The
flea population, consisting mostly of Xenopsylla
astia, in each chamber was many times more than
was found in a nest of the domestic rat.
Different subspecies of the domestic rat, Rattus
rattus (Linnaeus), are good and permanent hosts of
Xenopsylla cheopis in many parts of the world (see,
for instance, Advisory Committee, 1908, p. 245;
Hirst, 1927 a, p. 335), especially in the tropical and
subtropical countries. Wherever this flea is absent,
it is because it is replaced by other hardier species.
The depth of the burrows of this rat, examined in
the taluks of Barsi and Dharwar, was variable.
A typical underground burrow was not very deep,
its depth hardly exceeding 20 in. The humidity of
such a burrow kept under observation in the town of
Dharwar for about a year, fluctuated mostly between
50 and 80 %; but it is liable to be lower in dry and
higher in damp situations. The chances of fungous
growth on the debris and litter of domestic rat
burrows in both these taluks appear to be slight.
Thus the available food for flea larvae in such
burrows is unlikely to be rich in nutriment. Conse-
quently, it might be adequate for the larvae of
X. cheopis, but not for those of X. astia, whose nutri-
tional requirements are higher (see p. 257). A few
individuals of X. astia were found on the domestic
rats of these taluks owing to their close association
with Tatera indica or Bandicota malabarica; but they
could not establish themselves on domestic rats on
account of the poor larval food available in their
burrows.
The association of Xenopsylla cheopis with grain
in many parts of the world is well known (see Hirst,
1926, p. 163; 1927a, pp. 371, 398). The conditions
prevailing in most granaries and warehouses are
suitable for rearing of this species only (Hirst, 1927 b,
p. 94); in my opinion the debris present here has a
low nutritive value and is inadequate for the larvae
of X. astia. The presence of X. cheopis in the stores
of polished rice, other grains and cotton in the
mercantile promises of Rangoon (Jolly, Fenn &
Dorai, 1931, p. 1236), certain trade centres in the
plains of the Madras Presidency (King & Pandit,
1931, pp. 366, 369), and Colombo (Hirst, 1927a,
pp. 344-7,382; 1933, p. 93),where the indigenous flea
on domestic rats found in the residential premises is
exclusively X. astia, seems to be best explained by
the low nutritional requirements of the larvae of
X. cheopis; as a poor larval diet can only be available
in granaries well protected against the humid
climatic conditions of these areas. On the other hand,
the rat burrows in residential premises in these
areas provide a rich source of food on which the
larvae of X. astia can flourish.
The plateaux of Peninsular India are regions
where X. cheopis is abundant on domestic rats.
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 C ? For Release 1999/09/10: CIA-RDP83-00423RO01300270004-4
M CuARTF
was observed in the breeding jars owing to dampness
caused by high humidity during the rainy months.
The presence of fungus always resulted in excessive
increase of the flea population.
A burrow of the Indian domestic rat contains rat
and flea faeces, also the nesting material composed of
pieces of cloth, gunny bag and paper, strings of
cotton, jute and coir, raw cotton, dry leaves and
straws of fodder, etc. These items have not much
nutritive value for flea larvae; and this probably
accounts for a low flea infestation often found in such
burrows, especially in dry situations. An appreciable
increase in the flea population was observed during
the rainy months, when fungous growth on debris
and rat faeces in the burrow will occur. Possibly
fungous growth, which only occurs at relative
humidities higher than 70%, serves an additional
source of food. The fact that the larvae of the throe
Indian rat-fleas (Sharif, 1948) were reared on the
mixed diet of blood and yeast at low humidities (50
and 60 %), suggests that in the presence of sufficient
supply of vitamins of the B group, the association of
micro-organisms with the diet to supply accessory
food substances is not necessary. It is, therefore,
suggested that under dry conditions the source of B
vitamins may be different agricultural products that
are either found in undigested form in the faeces of
their hosts or intact in their burrows. If a larval
food with a low concentration of these vitamins is
available, as it would be in some rat burrows during
dry and hot months, breeding of fleas on a small.
scale night continue.
VI. INFLUENCE OF LARVAL FOOD ON THE
SPECIFIC DISTRIBUTION AND HOST PRE-
FERENCES OF THE THREE INDIAN RAT-
FLEAS
The facts of distribution of X. cheopis, X. brasiliensis
and X. astia in India are fairly fully known. They may
be partly explained by zoogeography. There is no
doubt of the fundamental importance of this factor;
but it is difficult to see that it could continue to be
important for the ectoparasites of the domestic rat
which is dispersed so much through human agency.
Trade through ships and other modes of transport
plays a great part in the dispersal of these rat-fleas,
either by transferring them from one place to another
or through the agency of their hosts. Climatic con-
ditions prevailing at a place of importation on the
bionomics of fleas also control their distribution.
I do not find that these factors suffice to explain the
presence or absence of the three species of rat-fleas
inside India. As fleas are temporary ectoparasites
and inhabitants of the nests or retreats of their hosts,
many species have become highly specialized not
merely in regard to the blood of some particular
host, but as to its nesting conditions. It may be th it
conditions in the burrow make great differences fo
larval nutrition and therefore to the absent e,
presence or abundance of flea species. Indubitably,
the range of the possible diet of a flea larva is a wile
one; but the larvae of all the species are not alike in
their food requirements as `some do not succeed on
food that gives good results for others' (Bacot, 1914,
p. 513). It is also known `that no insect can develop
on a food which is lacking even in one importa at
constituent' (Fraenkel & Blewett, 1943b, p. 48+i).
My own observations in the laboratory on tae
dietetic requirements of the larvae of differe at
species of the Indian rat-fleas support these assum p-
tions. In the field I have made observations on tae
rodent biology, which also seem to be relevant.
The examination of about 160,000 fleas of both
wild and domestic rodents of the Barsi and Dharw ar
taluks for about 3 years, and the study of th sir
burrow conditions, have enabled me to determi ae
some factors that control the irregular distributi :>n
of the three Indian rat-fleas. These two well-
separated taluks lying in the Deccan Plateau have
different climatic conditions, Barsi being warner
than Dharwar. X. cheopis was predominantly fou id
on the domestic rat, Rattus rattus rufescens (Gray), of
the Barsi taluk. Xenopsylla brasiliensis was present
only on the domestic rats, Rattus rattus rufescens a id
R. rattus wroughtoni (Hinton), of the cooler uplar. ds
of the Dharwar taluk along with Xenopsylla cheox is,
where infestation of the former flea at some places
amounted to 40-56 % of the total fleas. But. V.
brasiliensis was almost. absent on these domestic n its
of some of the adjoining warmer villages, even when
situated within about 1-4 miles of those that had t us
species; in these villages X. cheopis was almost
exclusively found as in the comparatively warn per
regions of this taluk. On the other hand, X. astia v as
present to the exclusion of other fleas on the Indian
gerbille, Tatera indica (Hardwicke), found in fiells,
and predominantly on Bandicota malabarica (Shaw)
in houses, all over these two taluks, Xenopsylla
astia was also present in very small proportions on
the domestic rats of those houses that harboured
Bandicota malabarica; but it was not found in hou>es
free from this rodent. The fact that only Xenops~ lla
cheopis is found on domestic rats and X. astia on
Bandicota malabarica in the same house, and that I he
latter flea is the only species found on the w ild
rodent, Tatera indica, in the same village, militates
against the idea that the distribution of these flea; is
governed exclusively by climatic factors (Taylor &
Chitre, 1923, pp. 625-7), or by zoogeographi:,,al
principles (Hirst, 1927a, pp. 317-30). It see ins
evident that in nature some other biological facto] - of
a greater potency is operating: it is difficult, if not
impossible, to escape the conclusion that this fac for
is the larval food.
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 CPYRGHT
Apprnvcrl I:nr Pclcacc 1000/f1Q/1f1 ? f _IA-PnPR3-nnA9,ipnni inn97nnnA-d
258 Nutritional requirements of flea larvae
necessary for the growing larvae to wait for importa-
tion and multiplication of micro-organisms to ensure
their successful growth. It is, therefore, evident that
this food fulfils the essential requirements of an ideal
diet for the larvae of these species. Yeast by itself
(Sharif, 1937, p. 233) has no food value for flea larvae.
Possibly the yeast proteins are an inadequate diet
for them; but yeast possesses growth-promoting
substances, the vitamins of the B group. It appears
that the native proteins of blood and B vitamins
form an ideal food for flea larvae.
There is evidence from insects of many orders of
the importance of vitamins of the B group; for the
larvae of certain beetles and moths infesting stored
products (Fraenkel & Blewett, 1943 a, pp. 506, 507;
Blewett & Fraenkel, 1944, p. 220), and the blow-fly
larvae (Hobson, 1933, p. 1908; 1935, p. 1290) cannot
grow without them. In these insect larvae the source
of these vitamins is micro-organisms which synthe-
size them in the food. Similarly, it is suggested that
when the available food of flea larvae is intrinsically
deficient in B vitamins, the association of micro-
organisms with it is essential for their normal
development.
It seems possible that when fleas food on a plague-
infected rat their excrement, due to the presence of
Pasteurella pestis (Advisory Committee, 1907a,
p. 404), may contain materials unusually favourable
to their larvae, if they happen to devour that excre-
ment. In my view this may help to explain the great
numbers of fleas which have often been observed on
rats or trap guinea-pigs in plague-infected houses
(see, for instance, Advisory Committee, 1907 b,
p. 443; Hirst, 1926, p. 221). It is, of course, admitted
that other factors, e.g. favourable climate and con-
centration of fleas on a few surviving rats, contribute
to the same result (see Hirst, 1926, p. 249; 1927 a,
p. 342) ; but the phenomenal increase of fleas that is
usually found in plague-infected houses cannot be
explained by these two factors alone. My assump-
tion is strongly supported by the results of the `pit
experiments' of Webster & Chitre (1930, p. 706) on
the transmission of plague by Xenopsylla astia and
X. cheopis. The flea population in the pits increased
to such an extent in about a month's time-a period
enough for a single generation of fleas in the climate
of Bombay-after the introduction of the plague-
infected rats, that it caused a heavy mortality
amongst rats owing to flea worry and excessive
sucking of blood. Heavy infestation of sick rats with
fleas, as has been observed by the Advisory Com-
mittee (1908, p. 254) and Bacot (1914, p. 472), might
be due to the sick rats providing accessory food
factors for the larvae of fleas, through the infection of
blood with pathogenic micro-organisms.
Flea larvae usually feed on decaying organic
matter containing micro-organisms, an association
of micro-organisms with the larval food may there-
fore be essential to some species; but at present the
evidence on this point is only indirect. The possibility
that flea larvae ingest fungi* has been suggested
elsewhere (Sharif, 1948). The exact nutritive value of
fungi is as yet unknown; but according to Chapman
(1931, p. 159), `Plant and animal residue may be
used more or less directly by the fungi; and the
fungi, by the insect.' The fact that premises storing
manure, composts and dungs are comparatively
more heavily infested with fleas than those without
them, indicates that saprophytic fungi may play
some part in the increase of fleas.
The existence of `lagging larvae' of the three
Indian rat-fleas on a diet of wheat flour (seep. 255) is
definitively suggestive of the occurrence of some
gradual and favourable change in this food. Such
larvae are the result of malnutrition (Sharif, 1937,
p. 232) and not of diapause. The gradual growth of a
small quantity of mould on the dead larvae and the
food, which perhaps was only sufficient to bring a
proportion of larvae to the adult stage, may have
allowed others to live much longer than is normal.
The marked disparity in growth rate of flea larvae
might indicate slow and gradual supply of some
other nutritive material to them, in addition to
what was present in this food at the beginning of
the experiment.
Earlier workers had great difficulty in getting con-
sistent results in breeding flea larvae. In my opinion
the partial and variable success in rearing flea larvae
obtained by Bacot (1914), Webster (1930) and Sikes
(1931) on different diets, but only at a relative
humidity of about 70 % and higher, was due to the
presence of a few micro-organisms, possibly fungi, in
the food at some later stage. The fact that a higher
percentage of mortality occurred in the beginning of
my experiments (see p. 255) supports this assump-
tion.
In nature in a domestic rat burrow I have never
come across such an enormous flea population as was
found in my brooding jars. Each jar had sea sand
and wheat grain, to .which a little dried horse blood
and yeast was added. For feeding adult fleas a white
mouse was put in a jar with a water supply, as
described by Leeson (1932, p. 26). The flea population
in each jar often increased to such an extent that
surplus fleas had to be removed several times a year
in order to avoid the death of the mouse. The jar
contained only flea and mouse faeces, partially eaten
wheat grain, and a small quantity of blood and yeast.
In addition, slight putrefaction and fungus growth
* Major W. L. Jellison, of the United States Public
Health Service, on a visit to the Haffkine Institute
about three years ago, informed me that he has soon on
several occasions spores and hyphae of fungi in the
alimentary canal of flea larvae. According to him, they
are more often found in the gut of the larvae of wild
rodent fleas.
Approved For Release 1999/09/10 : CIA-RDP83-00423RO01300270004-4
 CPAUT For Release 1999109/10: CIA-RDP83-00423 R001300270004-4
these two diets and no statistical difference existed
in their length measurements confirms the previous
conclusion (see p. 256) that addition of blood to flour
has not resulted in improvement in rearing of its
larvae.
The average length of a few adults of X. cheopis
(Table 3), obtained from the larvae reared on blood
alone, was not statistically different from that of
those whose larvae were nourished on flour alone or
the mixed diet of blood and flour. Only their
average breadth was significantly less than that of
adults from larvae on a mixture of blood and flour.
These facts indicate that the larvae of this species
that bred successfully on blood alone may have had
an opportunity of obtaining a small amount of an
accessory food substance.
It is, therefore, evident that the condition of the
adults of the three Indian rat-fleas,. as expressed by
their length and breadth measurements, is also a
good indication of the efficiency of the larval diets,
and they confirm my conclusions based on the
duration of larval life or combined larval and pupal
life, and on the proportions of larvae which became
pupae or adults.
V. DIETETIC REQUIREMENTS OF
FLEA LARVAE:
It is now known that the food available to flea larvae
consists of varied organic matter ; but there is still no
information regarding the actual food which they
select. In order to throw light on their exact nutri-
tional requirements, an attempt will now be made to
collect and combine all the available information on
the subject.
Blood is generally considered an integral part of the
larval food for almost all the fleas. But my recent ex-
periments on X. cheopis, X. brasiliensis and X. astia
(Table 1), and earlier ones (Sharif, 1937, p. 231)
on Nosopsyllus fasciatus (Bose) show that sterile or
pure, dried horse blood is an inadequate diet for the
larvae of these species; on blood alone successful
rearing of adults is not possible. Evidently blood
lacks some important factor necessary for normal
and successful breeding of them, which is compen-
sated by the addition of yeast, or possibly when blood
is contaminated with micro-organisms. The meagre
success obtained in rearing flea larvae on blood alone
(see p. 255) is attributed to the association of a few
micro-organisms with blood due to a chance con-
tamination, which increases its nutritive value by
providing vitamins of the B group, as in Rhodnius
prolixus Stal (Wigglesworth, 1936, p. 289; Brecher &
Wigglesworth, 1944, p. 224). Sikes (1931, p. 247)
obtained partial and highly variable success in
rearing flea larvae on blood at 80 and 90 % R.H. The
contradictory results obtained on this or other diets
by different workers may be due to the fact that flea
larvae have never been reared on sterile food.
My work also shows (Tables 1, 2) that highl 7
milled wheat flour without bran is an unfavourab] a
larval diet for the three Indian species of Xenopsyl&:.
There is, a high mortality and great irregularity i z
development; moreover, adults are small (Table i )
and pale yellow. It seems that the larvae swallow
much of the flour, but they do not digest it con.-
pletely, perhaps because their principal require-
ments are proteins and vitamins. To what exter t
slight fungous growth on dead larvae or on the floc :r
itself is a source of vitamins or energy I clo not know.
The addition of blood to wheat flour, howeve: ?,
shortened the larval life of the three Indian rat-fle? s
a good deal (Tables I', 2), and a comparatively larger
number of their larvae completed the active larve d
life, and without irregularity; this indicates that tr~ e
mixed diet is in some way more suitable. The fa( t
that a few larvae of X. cheopis that bred successfull y
on blood alone had significantly shorter actiN e
larval, and resting larval and pupal life than when it s
larvae were fed on wheat flour alone, suggests the t
flea larvae require food rich in nitrogenous sub-
stances. The mixed diet of blood and wheat flou ?,
however, lacks some important factors ; it is probab] e
that these are vitamins of the B group, and the 17
could not be supplied in adequate amount owing t o
the desiccating influence of 80 % ..x. on this die ;,
and also owing to the initial inadequacy of them i:i
the highly milled wheat flour devoid of bran. Th e
comparatively poor development of the larvae (f
X. astia on the mixed diet of blood andwheatflour an .1
on wheat flour alone may indicate that the vitamin 3
requirements of its larva are exceptionally high.
The adults obtained from the larvae of the three
species when nourished on the mixed diet of bloo I
and wheat flour were deep brown and fully sclorc -
tized, unlike those whose larvae fed on wheat flour
alone. The absence of proper siclerotization in th i3
adults of Nosopsyllus fasciatus, when its larvae wer a
fed on serum and yeast (Sharif, 1937, p. 232), and th:a
development of normal colour in those whose larv?.1
diet contained red corpuscles or haemoglobin alon
with yeast, clearly indicate that these materials
contain something, possibly iron, which Promotes
proper sclerotization. In this connexion it is pointy 1
out that the larvae of N.fasciatus, when fed on yeas t
and serum, to which ferrous ammonium sulphat:3
[FeSO4(NH4)2S04. 6H20] was added in the same car -
centration as iron in the haemoglobin, yielde 1
properly sclerotized adults.*
A mixed diet of blood and yeast gave the mot
rapid development of the larvae of the three specks
(Tables 1, 2), with almost 100 % emergence of adult;,
which were normally sclerotized. Possibly owing t:>
the high nutritive value of this mixed diet, it was nc t
* This fact was not mentioned in my earlier commun-
cation (Sharif, 1937), as it escaped my attention then,
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 CPYRGHT
A r.IA-RnPFt-1-0042-IROOI-100270004-4
256 Nutritional requirements of flea larvae
The general behaviour of flour exposed to the
atmospheric humidity of 80% denotes that it ab-
sorbed more water than the dried blood. The former
adhered to the larvae, but not to such an extent as
the latter. The flour definitely increased in volume;
but it looked slightly moist and discrete after 141
days' exposure to this humidity. If not disturbed
for a number of days, it formed a loosely held brittle
mass with sand, and a thin crust was formed on the
surface. When the larvae were present in the tube,
the surface of the food and sand mixture was always
covered with a large quantity of frass in the form of
fluffy flour. The larvae fed on this food were sluggish,
and only those that remained within cocoons bred
successfully. The ability of some larvae to spin
cocoons shows that flour at 80% R.H. contains
enough moisture to permit of cocoon formation. The
cocoons formed by the larvae fed on flour were smaller
and softer, having looser meshes, than those spun
by larvae fed on the mixed diet of blood and
yeast; this seems to show that the former food had
less moisture content than the latter (Sharif, 1948).
(c) Blood and wheat flour. On this mixed diet
(Tables 1, 2) 54.4 % larvae of X. cheopis and 48.4 %
of X. brasiliensis pupated, and the remainder died in
the resting stage after completion of their active
larval life. In contrast, only 58.2 % of the larvae of
X. astia completed their active larval life, and
40-7% of them pupated. Only 21-3% larvae of
X. cheopis, 9.7 % of X. brasiliensis and 24.2 % of
X. astiawere rearedinto adults. The addition of blood
to flour resulted in a considerable shortening of the
combined larval and pupal life of the three species.
A statistically higher mortality rate in the larval
stage and longer average active larval life on this
mixed diet in X. astia (Tables 1, 2) than in the other
two species, indicate that its larvae have more
particular nutritional requirements; moreover, the
food, at 80 % R.n., may give a less favourable atmos-
pheric condition. But a significantly shorter resting
larval and pupal life in X. astia than in the other two
species, suggests that those of its larvae which be-
came adults were able to obtain more nutritive food
owing to their prolonged larval life; possibly the
nutritional value of the food improved with the
length of exposure to this humidity.
The proportions of adults of X. cheopis and X. astia
(Table 1), when their larvae were reared on the
mixed diet of blood and flour, were not significantly
different from their proportions when reared on
flour alone ; similarly, no statistical difference existed
in rearing of adults of both these species on the
former diet. On the other hand, a significantly lower
proportion of the larvae of X. brasiliensis reached the
adult stage on this mixed diet than when they were
fed on flour alone, and also than when the larvae of
X. cheopis and X. astia fed on the former diet. This
shows a more pronounced desiccating influence of
the mixed diet on the pupae of X. brasiliensis than o
those of both the other species, as the proportion
its pupation did not differ statistically from that
either of the other two species on this diet, and als
from that when its larvae fed on flour alone.
marked desiccating influence of the mixed diet o
the pupae of X. cheopis and X. astia is also demur -
strated by the fact that in spite of the bettor growt
of their larvae on it (in comparison with flour alone',
there was no improvement in successful rearing L: F
the adults.
There was a little cocoon formation on this mixe
diet, and a fairly high mortality occurred in t
pupal stage owing to loss of water. Adults of hot
the sexes emerged indifferently and after great di -
culty from the pupal skins, and they were less acti
after emergence. Those facts bear testimony to t
dryness of this food.
Evidently, the nutritive value of this mixed diet
higher for the larvae of the three species than that
flour alone; but the desiccating influence of t
former diet, kept at 80 % R.x., was responsible f
a high rate of mortality.
The mixed diet of blood and flour increase
slightly in bulk at 80 % R.x. ; but it remained dry an
discrete throughout an exposure of 86 days, and we 3
dull red in colour. It adhered to the larvae and t
pupae so largely that they looked almost covore
with it. The larvae were very sluggish, and a lar
quantity of food was passed by them undigested.
(d) Blood and yeast. The combined larval and pup 1
life of the three species on the mixed diet of blood an
yeast was much shorter than on flour alone or t
mixed diet of blood and flour (Table 2), mainly d
to a statistically great reduction in their acti
larval life. Evidently, the` first diet has a muc
better nutritive value for flea larvae than the oth
two. The larval growth was regular on this mike
diet, as the interval between the first and the la
cocoon formation was only 4-5 days. The percenta
of cocoon formation was very high, and there we ~
almost 100 % pupation and adult emergen
(Table 1).
This mixed food seemed to gain more water tha
the others from the atmospheric humidity of 80 %;
did not adhere to the larvae and the pupae and was
bright red colour.
The dimensions (average lengths and breadths)
the adults of the three species (Table 3) reared fro
the larvae on blood and yeast were statistically muc
greater than those of the adults from the other diet
The adults of X. cheopis and X. astia (Table 3
whose larvae fed on the mixed diet of blood an
flour; were statistically longer and broader than the
reared on flour alone; this indicates the better nutr -
tive value of the former food. The fact that t
breadth measurements of both the sexes of X. bras -
liensis showed significantly inconsistent disparity o: i
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 CRp1 khTFor Release 1999/09/10: CIA-RDP83-00423R0013002 '0004-4
HARIF J
were noted. A mixture of blood and yeast was used
for control experiments, as it possesses all the
essential requirements of an ideal food for flea
larvae.
Sikes (1931, p. 245) has found that different kinds
of food have different hygroscopic properties, and
the optimum atmospheric humidity for rearing flea
larvae varied according to the kind of food employed
so as to satisfy their water requirements. The degree
of moisture content of the different diets tried, when
in equilibrium with 80 % R.H. at 25? C., has been
assessed roughly by noting the physical changes in
them and the behaviour of flea larvae when fed on
them. It was observed that whenever the water
content of a food was so low that it just permitted
flea larvae to grow, the food particles adhered to the
larvae and the pupae, and the fully grown defaecated
larvae failed to spin cocoons, perhaps because they
could not afford to lose water through secretion of
silken threads for spinning cocoons (Sharif, 1948).
Appreciable increase in volume of a dry diet at 80 %
R.H. denotes its high water content. Even variation
in the colour of diets, especially those that contained
blood, indicated different proportions of water. If
the colour of the food was dull red., its water content
was low; but if it was bright red, the water content
was high.
(a) Blood. Dried horse blood alone was com-
pletely unsuccessful as a larval diet for X. astia and
X. brasiliensis (Table 1); most of the larvae died in
the first instar, though 3.9 % of them in the former
species reached the third instar, and 3 % in the latter
formed small naked pupae after 29-42 days, from
which no adults emerged. It was also very unsuit-
able for the larvae of X. cheopis, but in this species
3-3% larvae bred successfully into small but
stronglysclerotized adults; most of them died in the
second instar. The fact that the average duration of
the resting larval and pupal life of this species
(Table 2) on blood alone was not statistically
different from that on a mixed diet of blood and
flour, or blood and yeast, suggests that the slight
success in rearing adults was due to a favourable
change that occurred in the dried blood on prolonged
keeping at 80 % a..$.
Only a few larvae of the three species grew slowly
and irregularly on blood alone, which was unsuccess-
ful in bringing about pupation and cocoon formation.
A significantly lower proportion of the dead larvae of
X. cheopis thanthat of X. astia on this food (Table 1)
indicates the simpler nutritional requirements of the
former species. In X. brasiliensis 160 larvae died in
different active instars in 13-55 (25-31?0-8319)
days, in X. cheopis 145 larvae in 13-49 (3248?
0.6965) days and in X. astia 178 larvae in 9-58
(31.32 ? 0.9215) days. The fact that only the average
period taken by the larvae of X. brasiliensis to die on
this food was significantly shorter than that taken
by the other two species, shows that blood. is mo: t
unsuitable for the larvae of this flea.
Throughout the exposure of 70 days to 80 % R.A.,
the blood remained dry, dull red and discrete; it di d
not swell appreciably, as its moisture content wt ,s
very low (see Sikes, 193 1, p. 244). The blood particlos
adhered to the larvae in largo numbers, especially t o
the dead ones ; this hindered the growth of fungus e n
the dead larvae, which normally occurs at this
humidity.
(b) Wheat flour. Highly milled wheat flour devoid
of bran is deficient if used as the sole diet, as on] y
27 % of larvae in X. cheopis, 42.9 % in _X. brasiliens s
and 20.5 % in X. astia were reared into adults, and
these after very long intervals (Tables 1, 2). Th.s
food gave rather better success with the larvae of
X. brasiliensis; the average active larval life of th.s
flea was statistically the shortest, though it w, ,z
significantly longer than that of X. cheopis when
reared on the mixed diet of blood and yeast.
When larvae are fed on flour, there is a considerab] y
longer active larval life, and a significantly highor
mortality rate in the larval stage and lower propo
tion of cocoons formed in X. astia than in the othor
two species (Tables 1, 2) : this might be attributed
either to insufficient moisture in the meal in equi-
librium with 80 % atmospheric humidity, or to Ls
comparatively low nutritive value for the larvae i of
this species. The latter alternative appears to le
more reasonable, as the fact that some larvae live d
a long time and spun cocoons demonstrates tie
presence of enough moisture in this food at this
humidity.
The growth of flea larvae on flour was irregular, t ,s
every developmental stage from the first. larva to tl .e
adult were found after 41 days in X. cheopis and
X. brasiliensis, and from the second larval instar i o
the adult after 60 days inX. astia. There were 10.5 Q0
lagging larvae in X. cheopis, 8.2 % in X. brasiliens s
and 15 % in X. astia ; they lived for 45-63, 40-55 an d
72-91 days respectively, and did not form cocoons or
pupae. When flea larvae (Table 2) were nourished
on an ideal diet of blood and yeast, all the adult
females emerged first, and then 2 days after tl e
males started emerging ; but when they were reared
on flour alone, the adults of both the sexes emerge d
indifferently. This fact and a marked disparity in tl e
developmental rate of flea larvae on flour indical a
that some favourable change had occurred in i'.,
which permitted successful breeding of some of ti e
larvae. The only appreciable change observed wt,s
that the dead larvae and flour had slight fungoi.s
growth. It is suggested that highly milled whet .t
flour without bran, by itself, is an insufficient diot
for flea larvae, and that association of micro-
organisms, such as fungi or perhaps yeast or bacteri, L,
with it was responsible for the successful growth
of some of them.
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 QPYRcHT J Jam,,
.~~.~ ^arnoii n
254 Nutritional requirements of flea larvae
only 1 g. was used; for a mixed diet I g. of each of
the constituents was thoroughly mixed before the
addition of the sand. In these experiments Merck's
`Yeast medicinal dry powder', dried horse blood and
highly milled wheat flour devoid of bran were used.
Every possible precaution was taken to avoid any
other organic substance coming in contact either
with sand or food. Sable's hair brushes and Petri
dishes, utilized for examination of the larvae, were
always thoroughly washed with soap and water.
Brushes were sterilized with absolute alcohol, and
Petri dishes were flamed. In no case was the same
brush or Petri dish used for two different diets.
Only completely unfed and recently hatched
larvae less than 24 hr. old were employed. The larvae
were reared in specimen tubes which were placed in a
desiccator, containing an atmosphere of 80 % rela-
tive humidity (R.H.) controlled by a mixture of extra
pure sulphuric acid (Merck) and water in a propor-
tion given by Buxton & Mollanby (1934, p. 174).
The desiccator was placed in a dark cupboard in
an air-conditioned room maintained at 25? C.
(77? F.) ? 1? C. All the experiments were conducted
under parallel conditions.
By breeding the three Indian rat-fleas on different
diets but under otherwise similar conditions, I have
attempted to isolate the nutritional factors and to
study their effect statistically. For assessing the
nutritive values of the diets the criteria adopted
were : (1) the duration of the active larval life and
that of the combined larval and pupal life for both
sexes, (2) mortality rate in the larval stage! (3) pro-
portion of cocoon formation or pupation, (4) pro-
portion of success in rearing of adults, (5) regularity
or irregularity in emergence of adults of both sexes,
and (6) variation in the size of adults. Most of these
features were statistically evaluated, and were sub-
jected to suitable tests of significance based on the
formulae given by Fisher (1941) and Fisher & Yates
(1943). In order to ensure the accuracy of results,
the experiments of each type were repeated for the
number of times entered in the column marked
`Experiments tried'. The results of all the experi-
ments of a type were pooled. The means given are
weighted averages. The tests of significance used
were the t and x2, using `Yates' correction for con-
tinuity' except when the numbers were too few and
the exact method of x2 was used. When tested in pairs
for significance, a result of comparison which is not
statistically different is denoted by the sign of -,
that which is significant at 5 % level is indicated by
+, and that at 1 % level by x. The signs in each
column of the tables indicate the level of significance
between a particular value, against which a sign is
inserted, and the one higher in the column with
which it is connected by an arrow.
Undoubtedly, the `best criterion for assessing the
suitability of a diet is the length of larval life, i.e. the
time from hatching to pupation' (Fraenkel &
Blewett, 1943b, p. 459); but in fleas whose larvae
spin cocoons, it is very difficult to ascertain the exact
duration of the complete larval stage. Consequently,
only the active larval life up to the time of cocoon
formation has been taken into consideration. In
cases where the larvae formed naked pupae, the
duration of larval life up to the resting larval stage is
assessed, as the time taken for cocoon formation
approximates to that.
III. HISTORICAL SURVEY
Since the time of Leewenhoeck (1683, p. 78), many
workers have tried to rear flea larvae under experi-
mental conditions. The diets used by them have been
mentioned elsewhere (Sharif, 1937, pp. 226-7). From
the results of Bacot (1914, pp. 513-33), Webster
(1930, pp. 398-403) and Sikes (1931, pp. 246-8), it
appears that the methods employed by them in
rearing flea larvae were not very successful, as a
fairly high and variable mortality occurred in their
experiments. In 1937 I described a standardized
food for flea larvae, consisting of dried horse blood
and yeast, which has been very successful, as almost
100 % success was obtained in rearing fleas from
larvae to adults. Further, this food has the ad-
vantage that its quantity and quality can be gauged
exactly. On consideration of my findings, Buxton
(1937, p. 12) suggested that yeast `presumably
supplies accessory food factors, one may suppose
that under natural. conditions micro-organisms
serving the same purpose occur in fragments of
bedding or of rat's dung'.
In view of the different role of species of flea in
the epidemiology of plague (Hirst, 1923, p. 817),
the question of the distribution of three species
of Xenopsylla Glinkiewicz in India has gained great
importance. Consequently, many workers (see, for
instance, Cragg, 1921, 1923; Hirst, 1926, 1927a, b,
1933; Sharif, 1930) have given detailed records of
their distribution in India, Burma and Ceylon.
Buxton (1941) has mapped their distribution in the
world. In spite of these attempts the irregular
distribution of these rat-fleas still defies reasonable
analysis.
IV. EFFECTS OF DIFFERENT DIETS ON THE
DEVELOPMENT OF THE LARVAE OF THE
THREE INDIAN RAT-FLEAS
In order to determine the comparative nutritional
requirements of the larvae of the three Indian rat-
fleas, their recently hatched and unfed larvae were
reared on (a) blood alone, (b) highly.milled wheat
flour devoid of bran, and mixed diets in equal parts of
(c) blood and wheat flour, and of (d) blood and yeast.
The differences in their development on these diets
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
duthor's Presentation Copy
[FaoMPARASITOLOGY, VOL. 38, No. 4, FEBRUARY 1948]
[All rights reserved] PRINTED IN GREAT BRITAIN
NUTRITIONAL REQUIREMENTS OF FLEA LARVAE, AND
THEIR BEARING ON THE SPECIFIC DISTRIBUTION AND
HOST PREFERENCES OF THE THREE INDIAN SPECIE
OF XE.NOPSYLLA (SIPHONAPTERA)
BY M. SHARIF, D.So. (PANSAB), PH.D. (CANTAB.), F.N.L, B.M.S.(I).
Assistant Director in Charge of Department of Entomology,
CPYRGHT Haffkine Institute, Parel, Bombay (India)
PAGE
1. Introduction . .
253
II. Methods and technique .
253
III. Historical survey . . ..
254
IV. Effects of different diets on the develop-
ment of the larvae of the three Indian
PAGE
V. Dietetic requirements of flea larvae 251
VI. Influence of larval food on the specific
distribution and host preferences of the
three Indian rat-fleas 25:
VII. Summary 2 611
References 26i
1. INTRODUCTION
It is now known that stored agricultural products
(see, for instance, Buxton, 1932, p. 291; Hirst,
1927 a, p. 405), such as cereals, pulses, fodder,
cotton, etc., serve as convenient vehicles for the
transport of rats and their fleas from one place to
another even at a great distance. The possibility of
transport of Xenopsylla cheopis (Rothschild) by
ships absolutely free from rats was hinted at by
Hirst (pp. 318, 420). The Advisory Committee (1908,
p. 255) suggested that the larvaeof fleas, `since they
can feed upon almost any kind of organic rubbish,
and pupae, which require no food, could be carried
considerable distances in merchandise, i.e. for
periods as long as one or two months'. The Committee
actually found (p. 241) a number of the larvae of this
rat-flea `in the sacking' in the neighbourhood of a
`nest made by ill. rattus on a grain bag'. In view of
the fact that the `factors governing transference of
the species of fleas from place to place are still im-
perfectly understood' (Hirst, 1933, p. 96), it was
considered necessary to ascertain whether the larvae
of X. cheopis, X. brasiliensis (Baker) and X. astia
Rothschild can breed sqccessfully on the flour of
cereals alone. As the stored grains, especially those
of wheat, rice, millets, barley, etc., are attacked by
insect pests, such as the larvae and the adults of
beetles, Sitophilus granarfus (Linnaeus), S. oryza
(Linnaeus), Tribolium confusum ]Duval, T. ferru-
gineum (Fabricius), Qryzaephilus surinamensis
(Linnaeus), Rhizopertha dominica (Fabricius) and
Sitodrepa panicea (Linnaeus), the larvae of moths,
Sitotroga cerealella (Olivier) and Ephestia kuehniella
Zeller, etc., small quantities of the excrement and
detritus that they produce are always present. Eggs
are laid by fleas indiscriminately in the stored
products, when rats infested with fleas visit them,
Larvae hatched from such eggs possibly may have
no food supply other than the flour dust (Bacot,
1914, p. 513; Hirst, 1927 a, pp. 397, 404), as owing
to the frequent shifting of the stored products, the
larvae of fleas are usually forced to live in an environ~
ment, in which there is little chance of the presence
of flea and rat faeces.
The findings presented here are based on experi.
mental work done in the laboratory and on about
3 years' field experience gained in an inquiry into the
recrudescence of plague in the districts of Sholapux
and Dharwar in the Bombay Province. The observa.
tions made provide a reasonable explanation for the
host preferences and the irregular and patchy distri.
bution of the three species of rat-fleas in India. Au
account of the ecological conditions governing the
burrows and nesting conditions of both wild and
domestic rodents in these districts will be publishec
later; but a few of the observations bearing on the
present problem have been incorporated in thi,,
paper.
II. METHODS AND TECHNIQUE
The methods employed for conducting the experi
ments were similar to those described in an earlier
communication (Sharif, 1937, p. 225). The different
diets used were given in a finely powdered form
thoroughly mixed with 5 g. of ignited and acid
washed fine quartz sand. In the case of a simple dies
25X1A9a
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
PUBLICATIONS OF
THE PAKISTAN ASSOCIATION FOR THE ADVANCEMENT OF
SCIENCE
Price Rs.
1. PAKISTAN JOURNAL OF SCIENCE CUM PAKISTAN
JOURNAL OF SCIENTIFIC RESEARCH (Quart) ...
20/- P.A.
2. PAKISTAN : A SELECT BIBLIOGRAPHY, 1951
by A. R. Ghani. xxii+339 pp. (9,000 references)
12/-
3. ANNUAL REPORTS OF THE PAKISTAN ASSOCI-
ATION FOR THE ADVANCEMENT OF SCIENCE,
1948, 1949, 1950 ... ...
1/- each
4. PROCEEDINGS OF THE PAKISTAN SCIENCE CON-
FERENCES 1949, 1950, 1951 (a'nnual, 3 pts. per volume)
5/- each
5. SOUVENIRS OF THE SECOND & THIRD PAKISTAN
SCIENCE CONFERENCES ... ...
1/8 each
6. A GUIDE TO THE CURRENT SCIENTIFIC JOUR-
NALS RECEIVED IN VARIOUS LIBRARIES OF
WEST PAKISTAN
by A. R. Ghani (Misc. Pubin. No. 1) ... ...
1/8
7. PERIODICAL PUBLICATIONS OF PAKISTAN
(Cyclostyled) ...
-f 8/-
8. SOME ASPECTS OF THE MODERN DEVELOPMENT
OF SCIENCE AND HIGHER EDUCATION IN
THE WEST.
by Dr. Bashir Ahmad (Misc. Pubin. No. 2) ...
9. COTTON PRESSED IN THE PUNJAB.
by Ch. Muhammad Afzal (Monograph) ...
(in press)
10. PLANT DISEASES IN THE PUNJAB
by Abdul Sattar and Abdul Hafiz (Monograph) ...
(in press)
Packing and Postage Extta
For further particulars, please write to
The General Secretary
PAKISTAN ASSOCIATION FOR THE ADVANCEMENT- OF, SCIENCE
University Institute of Chemistry, The Mall, LAHORE (Pakistan)
Printed by Mirza Mohammad Sadig at the Ripon Printing Press, Bull Road, Lahore
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Anornupd ~Fc1r Release 1999/09/10 : CIA-RDP83-00423 R001300270004-4
Wagner J. (1936a) Ober den Bau des Hinterdarms bei Flohlarven and seine
Verandertnmgen wahrend der Metamorphose beim Menschenfloh (Pulex
irritans L ) Zool. Jahrb., Abt. Anat. 61, 343-390, pls. viii-xi.
?- (1936b) 23 Ordnung : Flohe, Aphaniptera (Siphonaptera, Suctoria).
Die Tierwelt Mitteleuropas. 6 lfg. 2, Abt. 17, 1-24. Leipzig.
(1938) Vierter Nachtrag zum Kataloge der palaearktischen Aphanip-
teren. Konowia, 17, 8-18.
(1939) Aphaniptera. In Bronns Klassen and Ordnungen des Tierreichs.
Abr. 3, Buck. 13, Teil, f. 114 pp.
Webster, W.J. (1930) Observations on rat-fleas and the transmission of
plague. Part III. Ind. J. med. Res. IS, 391-405,
Webster, W.J. and Chitre, G.D. (1930a) Observations on rat-fleas and the
transmission of plague. Part II. Ind. J. med. Res. T8, 337-345.
-- (1930b), Observations on rat-fleas and the transmission of pluage. Part
IV. Ind. J. med. Res. i8, 407-425.
Wheeler, C. M. ani Dxuglas, J.R. (1945) Sylvatic Plague Studies. V. The
determination of vector efficiency. J. Inf. Dis. 77, 1-12.
Westwood, J. O. (1833) On the structure of the antennae in the order of
Aphaniptera of Kirby, with reference to the propriety of the establishment
of genera upon the variations of these organs. Entotn. Mag. 1, 359-363.
Wiggles worth, V B. (1932) Oa the function of the so-called `Rectal glands
of insects. Qart. J. Micr. Sci. 75, 131-150.
(1935) The regulation of respiration in the flea, Xenopsylla cheopis,
Roths. (Pulicidae. Proc. Roy. Soc. (B), 118, 397-419.
Wu Lien-Teh. (1934) Trans. 9th Congr. F. East. Associ. Trop. Med. 2, 735.
Nanking.
Wu Lien-Teh, Chun, J.W.H., Pollitzer, R. and Wu, C.Y. (1936), Plague : a
manual for medical and public health workers. xxxiii+547 pp. Shanghai.
Yersin, A. (1894) La Peste bubonique a Hong Kong. Ann. Inst. Pasteur, 8, 666,
667.
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 AffpftF, 11 Release 1999/09/10: CIA-RDP83-00423 R001300270004-4
avlovskij, E.J. (1926) "Zur vergleichenden Anatomie des mannlichen Geschle-
chtsapparats der Flohe." (In Russian with German resume). Rev. Russe,
Ent,- 20,..5-15.
ayne, J.F. in Allbutt, C. and Rolles.to-n, H.D. (1907) A System of Medicine, 2,
358.
rince, F.M, and Wayson, N.E. (1947) The survival of infection in fleas of bib-
. ernating ground squirrels. Publ. Hith, Repts. 62, 463-4-67, 1167-1168.
Rothschild, N.C. (1898) Contributions to the knowledge of the Siphonaptera.
Novit.. Zool. Lond. 5, 533-54.5, pls. xva-xvii.
(1915) A synopsis of the British Siphonaptera. Entom. Month. Mag. (3),
x, 49-112, pls. vii-xiv.
harif, M. (1930) A revision of the Indian Siphonaptera. Part I. Family Pulicidae.
Rec. Ind. Mus. 32, 29-62.
(1935) On the presence of wing buds in the pupa of Aphaniptera.
Parasitology, 27, 461-464.
--- (1937a) On.tht life history and the biology of the rat-flea, Nosopsyllus
fasciatus (Bose.). Parasitology, 29, 225-238.
---- (1937b) On the internal anatomy of the larva of the rat-flea, Nosopsyllus
fasciatus (Bose) Phils.;, Trans. Roy. Soc. (B), 277, 465-5'38.
(1940) Rept. Haffkine Inst, for r939. 43. Bombay.
(1945) On the structure of the so-called `penis' of the oriental cat-flea,
Ctenocephalides felis subsp. orientis (Jordan), and homologies of the
external male genitalia in Sipphonap'tera. Proc-. Nat. Inst. Sci. India, ii,
80-95, pl. ii.
(1948a) Nutritional requirements of flea larvae, and their bearing on the
specific distribution, and host preferences of the three Indian species of
Xenopsylla (Si.phonaptera).. Parasitology, 38, 253-263.
(1948b) The water relations of the larva of Xenopsylla cheopis (Sipho-
naptera). Parasitology, 39, 148-155.
(1949) l affects of constant temperature and humidity on the development
of the larvae and the pupae of the three Indian1 species of Xenopsylla
(Insecta t Siphonaptera) Phils. Trans. Roy. Soc. (B), 233, 581-633.
(1951) Spread of plague in the southern and central divisions of Bombay
province and plague eeridemic centres in the Indo-Pakistan subcontinent.
Bull. World Hlth,. Otg. 4, 75-109.
--~- (1952) On the structure of the head and thorax of the rat-flea, Nosop-
syllus fasciatus (Bose), [In progress].
harif, M. and Narasimham, A.S. (1942) Report of the .Iaffkine Institute for the
years 1940494t. 55-60. Bombay.
(1945) Report of the Haffkine Institute for the years t942-1943, 42-44.
Bombay.
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved YQ10 T 1999/09/10: CIA-RDP83-00423R001300270004-4
ikes, E.K. (1930) Larvae of Ceratophyllus wickhami and other species of fl as.
Parasitology, 22, 242-259.
immons, S.W. and Hayes, W.J. (1948) Fleas and disease. Proc. 4th Intern.
Congres. trop. Med. Malay. 1678-1688. Washington.
imond, P.L. (1898) La propagation de la Peste. Ann. Inst. Pasteur, az, 625-637.
mith, A. (1951) The effect of relative humidity on the activity of the tropi,::al
rat-flea Xenopsylla cheopis (Roths.) (Siphonaptera). Bull. ent. Res. 42,
585-599, p1. xxi.
nodgrass, R.E. (1935) Principles of Insect Morphology. ix+667 pp. New York.
-- (1944) The feeding apparatus of biting and sucking insects affecting man
and animals.. Smithson. Mis,;. Coll. zoo, No. 7, 113 pp.
- - (1946) The skeletal anatomy of fleas (Siphonaptera). Smithson. M sc.
Coll. 104, No. i8, 89 pp., 21 pls.
wellengrebel, N.H. (1913) Mededeeling omtrent Onderzoekingen over de
Biologie van Ratten en Vlooien en over andere Onderwerpen, die Betr(!k-
king hebben op de Epidemiologie der Pest op Ost-Java. Genee ~k.
T i jdeschr. Ned. Ind. 53, 53.
'aschenberg, O. (1880) Die Fldhe. Die Arten der Insectenordnung Suctoria mach
ihrem Chitinskelet monographisch dargestelit. 120 pp., pls. i-iv. Halle.
'iflov, V. and Ioff, I. (1932) "Beobachtungen fiber die Biologie der Flohe" ".In
Russian with resume in German) Rev. Microbiol. ii, 9-117.
'illyard, R.J. (1935) The evolution of the Scorpion-flies and their derivatiires
(Order Mecoptera). An. Ent. Soc. Amer. 28, No. I, 1-45.
'iraboschi, C. (1904) Les rats, les Souris, et leurs parasites Cutanes dans lears
rapports avec la propagation de la pest bubonique. Arch. Parasitol 8,
161-349.
rerjbitski, D.T. (.1904) "The part played by insects in the epidemiology of
plague Inaug. Thesis, St. Petersburg. [In Russian, translated into English
in 1908] J. Hyg., Camb. 8, 162-208.
Magner, J. (1889) Aphanipterologische Studien. I. Anatomie der Vermipsylla
alacurt Schimk. Hor. Soc. Ent. Ross. 23, 199-261, pls. vii-xi.
(1926) Zur Frage fiber den Kopfbau der Aphanipteren mit Beriicksicl ti-
gung ihrer Systematik. Zool. Anz. 67, 289-292.
(1930) Katalog der palaearktischen Aphanipteren. 55 pp. Wien.
(1932) Zur Morphologie der letzten Abdominalsegmente der Floli.e.
Zool. Jahrb. Abt. Anat. 56, 54-120.
(1933) Nachtrag zur Kenntnis der letzten Abdominalsegmente der Flohe.
Zool. Jahrb. Abt. Anat. 57, 365-374.
(1935) D:e Veranderungen des Mitteldarmes and die Regeneration seines
Epithels beim Menschenfloh wahrend der Metamorphose. Zool. ]at rb.
Abt. Anat. 6o, 263-288, pls. iii-iv.
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
PLEAS AND THE PART THEY PLAY IN P I.AGUE
(1935) Growth of blow-fly larvae on blood and serum. II. Growth in
association with bacteria. Biochem. J. 39, 1286-1291.
Holland, G.P. (1949) The Siphonaptera of Canada. Tech, Bull. Dom. Canad.
Dept. Agric. No. 70, 306 pp.
Hopkins, G.H.E. (1935) Some observations on the bionomics of fleas in East
Africa. Parasitology, 27, 480-488.
Hubbard, C.A. (1947) Fleas of Western North America. ix+533 pp. Ames,
Jellison, W.L. and Good, N.E. (1942) Index to the literature of Siphonaptera of
North America. Nation. Inst. Filth. Bull. No, 178, iv+193 pp.
Jordan, K. (1925) New Siphonaptera. N.ovit, Zool. Lond. 32, 96-112.,
(1926) On Xenopsylla and allied genera of Siphonaptera, III, Interna-
tionaler Entotnologen,Kongresz Zurich, Juli, 1925. 3, 593-624, pls. xvii-xx.
(Weimar).
--- (1933) A survey of the classification of the American species of Cera-
tophyllus s. lat., Novit. Zool. Lond., 39, 70-79.
(1950) On characteristics common to all known species of. Suctoria and
some trends of evolution in this order of insects. Eighth International
Congress of Entomology, 1-9. Stockholm.
Jordan, K. and Rothschild, N.C. (1906) A revision of the Sarcopsyl-
lidae,. a family of Siphonaptera, Thompson-Yates Johns. Lob. Rapt. (n.s.) 7,
15-72, pls. i-iv, Liverpool.
~.-. -. (1908) Revision of the non-combed eyed Siphonaptera, Parasitology, r;
1-100, pls. i-vii.
Jorge, R. (1928) "Rongeurs et Puce,;," Off. Inter., Hyg. Publ. Paris.
Karsten, N. (1864) Beitrag zur Kenntniss des Rhynchoprion penetrans. Bull.
Soc. Imp. Nat, Mosco, 37, 72-156.
Kessel, E.L. (1939) The embryology of fleas. Smithson. Misc. Coll. 98, No. 3
78' pp., pls. i-xii.
Kitaato,>S. (1894) Preliminary note on the bacillus of bubonic plague. Lancet,
2,428.
Koch, R. and Zupitza, M. (1808) Deutsche Med. Wschr. No. 28.
Kolenati,= F.A. (1863) Beitrage zur Kenntnis der Phthirio-Myiarien. for. Soc.
Entom. Ross. z, 9-109, pls. i-xv.
i taepelin, K. (1884) Uber die systematische Stellung der Puliciden. Fests-
chrift zum 5o jahrigen Jubilaum des Realgymnasiums des Johanneums. 17 pp.,1
pl. Hamburg.
Laboulbene, A. (1872) Metamorphoses de la Puce du Chat (Ptjlex felis, Bouche).
An Soc. ent, France (5), 2, 267.274, pl. xiii.
1.andois, L. (1866) Anatomie des Hundeflohes (Pulex canis Duges) mit
Berucksichtigung verwandter Arten and Geschlechter. Nov, acta Acad.
Loop. Carol. 33. 1-66, pls. i-vii.
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
3L
FOURTH PAKISTAN SCIENCE CONFtR$1s1CV .
Lass, M. (1905) Beitrage zur Kenntnis des histologisch-anatomischen Baues des
weiblichen Hundeflohes. (Pulex canis Duges s. Pulex serraticeps Taschen-
berg). Zeits. Wiss. Zoo!. 79, pp. 73-131, pls. v-vi.
Leeson, H.S. (1932) The effect of temperature and humidity upon the survival
of certain unfed rat fleas. Parasitology, 24, 196-209.
---- (1936) Further experiments upon the longevity of Xenopsylla cheolais
Roths. (Siph.onaptera). Parasitology, 28, 403-409.
Lima, A. da Costa and Hathaway, C.R. (1946) Pulgas, Bibliografia, Catalog:)e
animais por ela$ sugados. Monograf, Inst. Oswald Cruz, No. 4, 522 pp.
Link, V.B. (1951) Plague. Amer. J. Trop. Med. 31, 452-457.
Linnaeus, C. (1758) Systema Naturae, 10th ed. 824 pp. Holmiae.
Liston, W.G. (1905) Plague, rats and fleas. J. Bombay Nat. Hist. Soc. 16,
253-273.
Martini,. E. (1922) Die Eidonomie der Flohe, als Beweis fur ihre stammesge s-
chichtliche Herkunft. Central Bakt. Parasiten. Infeckt., I. Abt. Orig. 118,
205-221.
Martini, E. and Burgarth, H. (1923) Die Anatomie des weiblichen Hundeflotes
als Beweis fur die stammesgeschichtliche Herkunft der Flohe. Centralbl.
Bakt. Parasit. Infeckt. I. Abt. Orig. 90, 29-38.
Mellanby, K. (1934) The site of loss of water from insects, Proc. Roy. Soc. (13),
xi* 139-149.
Minchin, E.A. (1915) Some details in the anatomy of the rat-flea, Ceratophyl us
fasciatus Bosc. J. Quekett Micr. Cl. (2), 12, 441-464, pls. xxvi-xxxii.
Mitchell, J.A. (1927) Plague in South Africa : historical summary (up to Juti.e,
1926). Pub!. S. Afr. Inst. Med. Res. 3, 89.
Newman, E. (1851.) On the affinities of the - pulicites, an essay.. Zoologist, 9,
143-149.
Ogata, M. (1897) Ueber der Pestepidemie in Formosa. Cent. Bakt. $I, 769-777.
Oudemans, A.C. (.1909a) Neue Ansichten fiber dies Morphologie des Flahkopf Ys-,
sowie caber die Ontogenie, Phylogenie and Systematik der Flohe. Not it,
Zool. Lond. t6, 133-158,.xii-xiii.
(1909b) .Veber den systematischen Wert der weiblichen Genitalorgane
bei den Suctoria (Flohen). Zool. Anz. 34, 730-736.
Packard, A.S. (1894) On the systematic position of the Siphonaptera, w.th
notes on their structure. Proc. Boston Soc. Nat. Hist, 26, 312-355.
Patton, W.S. and Cragg, F.W. (1913) A Textbook of Medical Entomology.
xxxiv?764 pp. Madras.
Patton, W.S. and Evans, A.M. (1929) Insects, Ticks, Mites and Venomous
Animals of Medical and Veterinary Importance. Part I. x+786 pp.
Croydon.
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
P--'- n''_ FLAT IN T-
ragg, F.W. (1921) The geographical: distribution of the Indian rat 'fleas as a
factor in the epidemiology of plague : Preliminary observations, Ind. J.
med. Res.. 9, 374-398, pl. xxviii.
(1923) Further records of the distribution of the Indian rat fleas, with
a note on the correlation between the prevalence of..Xenopsylla cheopis
and plague mortality. Ind. J. med. Res. xo,"953-961.
;raampton, G.C. (1931) A phylogenetic study of the posterior metathoracic
and basal abdominal structures of insects, with particular, reference to the
'Holometabola. J.N.Y., Ent. Soc. 39, 323-357, pls. xx-xxiv.
urtis, J. (1832) British Entomology, 7. London.
Dahl, F. (1898) Die Stellung der Puliciden im System, Archiv. Naturges.6.5,
71-86,
alla Torre,. C.G. (1924) Aphaniptera orbis terrarum. (Synopsis praecursoria)
Naturwiss. Med. Innsbruck, 39, 1-29.
ampf, A. (1912) Uber den morphologischen Wert des Ductus . obturatori.us
bei den Aphanipteren weibschen. Abh. Kais. Leop.- Carol.. ,Deutsch. Akad.
Naturf. 97, No. 10, 1-9.
(1945). Notas sobre pulgas. I a VII. Rev. Soc. Mexic. Hist. Nat. 6, 47-70.
Davis, D.H.S. (1939) Some ecological methods in research on bubonic plague.
S. Africa J. Sci. 36, 438-444.
(1948) Sylvatic plague in South Africa : history of plague .fin man,
1919-43. Ann. Trop. Med. Parasit. 42, 207-217. . . .
evignat, R. (1951) Varietes de 1'espece Pasteurella pestis. Bull. World Hltho
Org. 4, 247.
uges, A. (1832) Recherches sur les caracteres zoologiques du genre Pulex, e
sur la multiplicite des especes qu'il renferme. Ann. Sci. Natur. (1), 27,
145-165, p1. iv.
dney, E.B. (1945) Laboratory studies on the bionomics of the rat. fleas,
Xenopsylla brasiliensis, Baker and X. cheopis, Roths. I. Certain effects of
light, temperature and humidity on the rate of development and on adult
longevity. Bull. ent. Res. 35, 399-416.
(1947a) Laboratory studies on the bionomics of the rat fleas. Xenopsylla
brasiliensis, Baker and X. cheopis, Roths. II. Water relations during the
cocoon period. Bull. ent. Res. 38, 263-280.
(1947b) Laboratory studies on the bionomics of the rat fleas, Xenopsylla
brasiliensis, Baker and X. cheopis, Roths.'III. Further factors affecting
adult longevity. Bull. ent. Res. 38, 389-404.
lbel,, R; E. (1951). Comparative studies on the larvae of certain species of
fleas'(Siphonaptera). J. Parasitology, 37, 119-126, pls. ii-iii.
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
30 FOURTH[ PAKISTAN SCIENCE C1ONPERENCt
Eskey, C.R. and Haas, V.H. (1939) Plague in the western part of the United
States: Infection in rodents, experimental transmissfdri by fleas, and
inoculation test for infections. Publ. Hith. Rep. 44, 14671481.
(1940) Plague in the western part of the United States, 'Publ. Huth.
Serv. Bull, No. 254, 1.83.
Ewing, H.E. (1929) A manual of external parasites. xiv+225 pp. Baltimore.
Ewing, H.E. and Fox, I. (1943) The fleas of North America. U.S. Dept. A?:r.
Misc. Pub(. No. 5ooy 142 pp.
Faasch, W.J. (1935) Darmkanal and Blutverdauung bei Aphanipteren. Zei ~s.
Morphol. Xholog. Tiere, 20, 559=584.
Fox, C. (1914) The taxonomic value of the copulatory organs of the females
in the order Siphonaptera. Treas. Dept. U.S. Publ. Hlth. Serv. Hyg. Lc b.
Bull. No. 97, 19-25, pls. vi-xxii.
Fox, I. (1940) Fleas of Eastern United States. vii+191 pp. Ames.
(1941) The siphonapteran thorax. Proc. Ent. Soc. Wash. 43, 6-11.
Fraenkel, G. and Blewett, M. (1943) Intracellular symbionts of insects a:: a
source of vitamins. Nature, Lond. 3152, 506-507.
Garnham, P.C,C. (1949) Distribution of wild-rodent plague. Bull. World Hlrh.
Org. 2, 271-278.
Gauthier, J.C. and Raybaud, A. (1903) Recherches experimentales sur le role
des parasites du rat daps la transmission de la peste. Rev. Hyg. Police
Sanit. 25, 426.
Golov, D. and Idff, I. (1927) Rep. rst All-Russian Anti-Plague Conf. Saratov.
102, 158.
Haliday, A.H. (1E356) On the affinities of the Aphaniptera' arhofg insects. Nit.
Hist. Rev. Proc. 3, 9.
Heymons, R. (1899) Die systematische Stellung der Puliciden. Zool Anz. ,62,
223-240.
Hirst, L.F. (1925) Plague fleas, with special reference to Milroy lectures.
J. Hyg., Camb. 24, 1.16.
(1926) Researches on the parasitology of plague. Part 1. Ceylon J.
Sci. (Sect. D), z, 155-271, pl. xxvi.
-- (1927a) Researches on the parasitology of plague. Part 2, Ceylon J.
Sci (Sect. D), z. 277-455.
(1927b) Rat-flea surveys and their use as a guide to plague preventcve
measures. Trans. R. Soc. trop. Med. HHyg. it, 87-108.
- (1929) Municipality of Colbtnbo ; report of the medical o, lcer of health.
Annexure A, report of the city mic?obiologigt for the year rg2q. 5 pp. Colour 10.
Hobson, R.P. (1933) Growth of blow-fly larvae on blood and serum. I. .1,e-
sponse of aseptic larvae tt7 vitatniii B, Biochem. J. 27 1899-1909.:
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
TJt D. . v R . --- 77
but it roust be pointed out that exclusive attention to the control of fleas and
rodents without adequate knowledge of their ecology may lead to waste of
effort, as past experience clearly paints out. This can be remedied by sub-
sidizing researeh on the ecology of fleas and rodents in institutes interested in
this type of work.
Pakistan cannot afford to neglect research on fleas and other disease-
carrying insects, It must have a research institute with an active band of
workers so as to make valuable contributions, and earn its rightful place amongst
the progressive nations of the world.
VIII. REFERENCES
Advisory Committee (1906a) Experiments upon the transmission of plague by
fleas. J. Hyg., Camb. 6, 425-482.
(1906b) The physiological anatomy of the mouth parts and alimentary
canal of the Indian rat flea, Putex cheopis, Rothschild. J. Hyg., Camb. 6,
486-495, p1. ix.
- ?(1906c) On the existence of chronic plague in rats in localities where
plague is endemic. J. Hyg., Camb. 6, 530.
-=---(1907a) Further observations on the transmission of plague by fleas,
with special reference to the fate of plague bacillus in the body of the rat-
flea. (P, cheopig). J. tlyg., Camb , 395=420.
(1907b) On the external anatomy of the Indian rat flea (P. cheopis), and
its dfl'erentiation from some other common fleas. J. Hyg., Camb. 7,
446=456, pls. x-xii.
-(1908) Observations on the bionomics of fleas with special reference to
Pr chebpis, J. Uyg., Camb. 9, 236=259.
-(1910a) Resolving (chronic) plague in rats. J. Hyg., Camb. 10, 335-348,
p1. viii,
(1910b) Interim report of the Advisory Committee for plague investi-
gations in India. _ J. Hyg., Camb. zo, 566-568.
(1912) Observations on flea breeding in Poona. I. Hyg., Camb. 12,
Plague Supplement, a, 300.325.
Almeida Cunha, R. de. (1914a) Contribuicao para, o estudo dos sifonapteros do
Brazil. 212 pp., 2 pls. Rio de Janeiro.
(1914b) Contribuicao para o conhecimento dos sifonapteros brazileiros.
Mem. Inst. Oswaldo Cruz, 6, 124436, pls, xiii-xiv.
13acot, A, (1914) A study of the bionomics of the common rat fleas and other
species associated with human habitations, with special reference to the
influence of temperature and humidity at various periods of the life
history of the insect. J. Hyg., Camb. 13. Plague Supplement, 3, 447-654,
pls, xxvii~xxxiv,
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
Bacot, A,W. (1915) Further notes on mechanism of transmission of plague
by fleas. J. Hyg., Camb. 14, 774.
Bacot, A. W. and Martin, C. J. (1914) Observations on the mechanism of
transmission of plague by fleas. J. Hyg., Camb. 13, Plague Supplement:, 3,
423-439, pls. xxiv-xxvi.
(1924) The respective influences of temperature and moisture upon the
survival of the rat-flea (Xenopsylla cheopis) away from its host. J. Hyg?,
Camb. 23, 98-105.
Baker, C. F. (1904) A revision of American Siphonaptera, or fleas, together
with a complete list and bibliography of the group. Proc. U. S. Plat.
Mus. 27, 365-469, pls. x-xxvi.
_(1905) The classification of the American Siphonaptera. Proc. U.S. Plat.
Mus. 29, 121-170.
Berth, F. (1878) Contribution all' anatomia ed alla fisiologia delle antennae
degli Afanitteri. Atti. R. Acad. Lincei anno. (3) Mem. Class. Scien. fisi he,
2, 24. Roma.
Bishopp, F.C. (1931) Fleas and their control. U.S. Dept. Agric. Farmers' Bull.
No. 897, 1.16.
Bonnet, G. (1867) Memoires sur la puce penetrante ou Chique. Arch. hied,
nav. 8, 86,:2 pis.
BOrner, C. (1904) Zur Systematik der Hexapoden. Zool. Anz. 27, 511-533.
Bosc d' Antic, L.A.G. (1801) Description d'une nouvelle espece de puce
(Pulex fasciiatus). Bull. Sci. Soc. Philomath. Paris 2, No. 44, 156, also in
Widemann's Archiv. Zool. Zootom. 3, 186. (1802).
Bouche, P.F. (1835) Beitrage zur Insectenkunde. II. Bemerkungen fiber die
Gattung Pulex. Nova Acta Physico-Medica Acad. Caes. Leo p. Carol. 317,
501-508.
Buxton, P.A. (1932) The climate in which the rat-flea lives. Ind. J. med. des.
zo, 281-297.
(1933) The effect of climatic conditions upon population of insects.
Trans. R. Soc. Trop. Med. Hyg. 26, 325-356.
(1938) Quantitative studies on the biology of Xenopsylla cheopis
(Siphonaptera). Ind. J. med. Res. 26, 505-530.
(1948) Experiments with mice and fleas. I. The baby mouse. Parasito-
logy, 39, 119-124.
Chick, H. and Martin, C.J. (1911) The fleas common on rats in different parts
of the world and the readiness with which they bite man. J. Hyg., Carnb.
II, 122-136, pl. ii.
Cholodkovsky, N. (1914) Zur Beurteilung der systematischen Stellung der
Puliciden..Zool. Anz. 43, 555-558.
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
FLEAS. AND.Tti ART THEY LAY' N LAG17E
The-Central African endemic centre is said to have been established as late as
1897 (Koch and Zupita, 1898) ; but according to some workers it is certainly of a
very.old standing, and. may be the original home of plague. Payne (1907), how-
ever, considers it only a colony of the_ Asian endemic centre., The remaining,
centres, i.e., South African, Californian and South American, are fundamentally.
different from the Central Asian Centre, because in them wild rodents were not
primarily involved ; but received infection from domestic rats during the present
pandemic only.
It appears that many of the plague endemic centres have escaped detection,
and further work is required to delimit precisely all the endemic centres in the,
world. The conditions governing these endemic centres ,..have been little studied.
Sharif (1951) studied conditions prevailing in an endemic centre in. the Western
Ghats in. the Bombay Province for about eight. years. In. this Province wild,
rodents. do not play any part in the perpetuation of plague ; only the domestic
rats are involved.
According-to Sharif (1951), in the Bombay Province two distinct types- of:
plague epizootics exist. In the warm, low tablelands and plains, the infection is
often severe, leading to a very heavy mortality among rats, which results in
disappearance of the disease within a short time. The re-occurrence of plague in
them is due to fresh importation. In the cooler regions comprising the water-
shed of the Western Ghats, the infection is slow-spreading and persists for a'
long time, owing to lower rat mortality due to the retarding effect of the com
paratively low temperature on the increas of flease and of plague bacilli in
them. The recrudescence of plague in many places of these areas is the result of
carry-over, which are considered to constitute an endemic Prague centre.
Plague often radiates from an endemic centre. The necessary factors go- ernin4
such a centre .appear to be moderately damp and cool climatic conditions for a
greater part of the year, which keep the soil in the rat-burrows moderately"
moist: These conditions permit continuou good breeding of rat-fleas in
burrows and their wandering away from them.
Plague endemic centres are found at an elevation of 1,000 to 2,000 feet in
the temperate regions and 2,000 to 4,000 feet in the tropical. ones (Hirst, 1929)
having an annual rainfall of 20-40 inches, encountered in the submontaje
regions of the Himalayas and in the.gradual slopes of mountains, such as the,
watersheds of the lower mountain ranges in central. and peninsular India, .re.
spectively. The disease does not, occur in excessively damp areas such, as East
Pakistan and Assam, and excessively dry areas like the deserts .have never
shown endemicity of plague. The complete absence of plague from extremely
wet areas is due to the harmful effect of excessive moisture in combination with
a soil rich in organic material on the breeding of rat-fleas (Sharif, 1949).
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
r'OURTH PAKISTAN SCIENCE CONFERENCE
Plague is a migratory disease, and even in an endemic Centre it is never con-
fined to any one place, though it persists in certain adjacent areas having sin liar
climatic conditions. Such areas have been defined by Sharif (1951), in the eas :ern
gradual slopes of the Western Ghats in Dharwar, Belgaum, Satara and Pcona
Districts.
From the past records of plague incidence in the Indo-Pakistan Subconti-
nent, Sharif (1951), has delimited seven endemic centres in the subcontinent-
Three of them are located in the submontane plains of the Himalayas. Of the
others, three are found in the water-sheds of the mountain ranges of Southern
India and one in those of Central India.
Because of the absence of plague in the human population of West
Pakistan in recent years, the people of Pakistan should not be lulled into a sense
of security, for any such security may easily prove a false one. Plague all
through history has had periods of quiescence and recrudescence. No one
can tell when the disease will strike again and where. A part of one of the
sub-Himalayan endemic centres is in the Punjab.
Commendable progress has been made in our knowledge of fleas during
the last fifty years ; but need for further expansion of our knowledge of t;iese
dangerous insects will be readily admitted. Fleas have been considered rem irk-
able insects for the difficulties they present in understanding them, and for
dangerous diseases like plague and typhus which they transmit. Our -time
appears especially to demand a well-planned study of these insects. A know
ledge of them is of the utmost importance for defence in the bacterial wari-are.
Fleas are said to have been used once in starting plague during the last war.
The morphology of fleas is a great stumbling block in our way to un ier-
stand their various aspects. It is a subject which can be studied effectively only
in institutions interested in pure research and by entomologists, well versed in
insect morphology.
The taxonomy of fleas needs greater efforts than have been made hithE rto.
It is hoped that the recent attempt by Dr. K. Jordan and his colleagues at the
Triog Museum, Herts (England) to bring workers on fleas closer by kee Ding
them in touch with one another's activity would lead to their working as a team
to put the classification of fleas on a proper footing. The house of Rothschilds
has already made a valuable contribution by building up the richest collecticn of
fleas in the world. It is hoped that further help would be forthcoming; to
prepare a greatly needed monograph on the fleas of the world.
The attempt by the World Health Organization to combat flea-b:>rne
fJ is'nsPS 1ikP typhus and plague as a long-term policy is a step in the right direction
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
LE AND THE ART THEY LAY IN PLAGUE
ventriculus of an infected flea that they blocked the passage, so that blood could
not enter the stomach, and that, in the attempts of such a flea to feed, blood
carrying organisms were regurgitated and injected back into the wound.
Hirst has (1925) observed that the vector efficiency of fleas varies according
to the species, and that X. cheopis is the most efficient, which partly explains the
patchy distribution of plague in areas having similar climatic conditions. Among
the important vectors of plague (see Simmons and Hayes, 1948) are X. cheopis
and N. fasciatus in places where domestic rats play part in plague,
Diamanus montanus (Baker) and Hoplopsyllus anomalus (Baker) in the western
part of the United States of America, N. silantiewi (Wagner) and N. tesquorum
(Wagner) in Mongolia, Rhopalopsyllus cavicola in Argentina and Ecuador,
X. eridos Rothschild, Dinopsyllus lypusus Jordan and Rothschild and Chiasto-
psyllus rossi (Waterston) in South Africa, X. brasiliensis in Uganda, Kenya and
Nigeria and P. irritans in several parts of the world.
E~key and Haas (1939) determined the infectibility and infectiousness of
31 species of rodent fleas, five of which are found in the Indo-Pakistan Sub-
continent. All fleas became infected ; most of them continued to be so through-
out their life ; but 4 per cent of X. cheopis and 12-19 per cent of the other
species became purified or uninfected. Only blocked fleas belonging to 15
species transmitted plague. In X. cheopis the masses of organisms are first
formed in the proventriculus, but in most other fleas they are first formed in the
stomach, and produce blockage by a secondary invasion of the proventriculus ;
consequently, the blockage occurs much earlier in X. cheopis than in other fleas.
It is for this reason this species is considered the vector par excellence.
Normal fleas seldom feed longer than 4 minutes at a time, and would hardly
attempt to feed more than once in 24 to 72 hours. Blocked fleas, however, feed
as often as every hour or two, remaining longer at one place. Extrinsic incuba-
tion, period of the infection. varied from 5 to 130 days, being 5-31 days in
X,-chopis, and it was influepced by the temperature, being longer at a lower
temperature. The average length of life of. fleas after they transmitted plague
was. only 3.2 days. Fleas of many species may harbour plague organisms with-
out ill effects and lived fora to 3 months ; a few even lived for over 5 months ;
but X, cheopis died in the shortest time after infection, being 17 days at. 18.9?C.
and 12 days at 22.2?C.
The factors which determine the transmitting power of a particular species
arethe infection potential, vector potential, transmission potential, extrinsic
incubation, life span of the flea both when infected and uninfected, feeding
habits and other ectoparasite relationships. Wheeler and Douglas (1945)
developed a simple standardized method for ascertaining the vector efficiency
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
l.'OURTH PAKISTAN SCIEI4CE COWPERENCE
of a flea species by calculating the product of the numerical values of its in: eci
tion, vector and transmission potentials : more simply, the average number of
transmissions by an individual of the species. According to them the vector
efficiency of X. cheopis is only inferior to that of D. montanus, a wild rodent ::lea
of the United States of America.
(c) Spread of Plague and Endemic Centres
Besides the earlier doubtful records of plague outbreaks, three gi eat
pandemics of plague have overrun the world. The first pandemic, the "Justinian
plague", which originated from Pelusium in 542 A.D., was responsible for 100
million deaths, and carried off half the population of the Roman Empire. The
second pandemic which started in Asia reached its zenith in the fourteenth
century, spreading all over the old world. Owing to pneumonic complications
it was called "Black Death" in Europe, where it killed about 25 million peo ale,
i.e., about one-quarter of its population. The third or present pandemic started
from the Yunan plateau in 1893, and within a short time nearly every- country
became involved. In the Indo-Pakistan subcontinent alone it has killed over 12
million people in about fifty years. Recently, Devignat (1951) has shown i hat
these three pandemics were caused by three different strains of P. pestis ; the
first one was due to var. antiqua, second one to var. mediaevalis and third one; to
var. orientalis.
Whenever a pandemic wave of plague recedes from a country, endemic
foci comparable to stagnant pods left behini by the lowering tide, exist in
moderately cool and damp regions, which continue to serve as perpetual sources
for the dissemination of plague. Such endemic foci were left by the sec rnd
pandemic in the Near East, and by the third one in India and some other
countries. These: radiate plague to neighbouring areas with a secular tendency.
The question of ancestral home of plague has attracted the attention of
many workers (see Wu Lien-Teh et al., 1936), and some of them suggest that
the Central Asian plateaux are the, original home of plague, for the simple reason
that plague foci in them belong not only to the past, but have remained impa.red
up to the present time. Even the European epidemics have been traced back to
them. Five plague endemic centres have usually been recognized in the world
Central Asian, Central African, South African, Californian and South Ameri,:an.
The Central Asian endemic centre is the oldest in which wild rodents like
tarabagan and marmot species are also involved. Wu Lien-Teh (1934) opines
that the whole of this vast area with its profuse wild rodent population "m !ght
be compared with a heap of embers, where plague smoulders continuously and
from which sparks of infection may dart out now and then in various directio as".
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
Wu Lien-Teh, Chun, Pollitzer and Wu, 1936), which are considered abundant
in certain seasons of a year and scarce in others. Consequently, a regular
alternation between the plague seasons and off-seasons occurs. This is 'not
borne out by the studies of Sharif and Narasimham (1942, 1945). It is not
so much the seasonal fluctuations in the flea population that control the
propagation of plague, but the behaviour of adult fleas towards climatic
conditions. During a plague season a large number, of fleas accompany rats
during their movements and are thus scattered at random, which helps in the
spread of plague; moreover they can remain for a longer time on the human
body and in the personal effects during the plague season and thus cause
severe epidemics. Whilst during the off-season very few fleas accompany rats
and are scattered, and they cannot remain on human body, even when a large
number of them may be present in rat burrows, This results in retardation
or inhibition of the propagation of plague, and the infection during off-season
at certain favourable places pursues the course of a slow subterranean
enzootic from burrow to burrow. Evidently, the behaviour of adult
fleas plays an important part in tiding over the off-season. Many workers
(see Bacot, 1915 ; Eskey and Haas, 1939) have shown that infected fleas
can live for several months on their host without transmitting the disease,
These two factors affecting fleas play the most important part in carry-over of
plague from one season to another.
It is said that wild rodents like tarabagans, marmots, etc. (Wu Lien-Teh,
et at., 1936), when infected towards autumn, may undergo normal hibernation
harbouring plague bacilli at or near the site of entry, and on awakening in spring
this latent infection becomes active and leads to generalized plague with
bacteraemia. But plague predominates in domestic rodents which do not
undergo hibernation. Consequently, kindling of latent infection in nature cannot
play any part in tiding over the off-season. It may, however, play some part in
sylvatic plague in cold countries.
There are a number of factors in nature, which operate against the wide
dispersal of plague. There is no active migration in the case of domestic rats.
The chances of their passive migration are comparatively few. Domestic rats
can be easily carried from one place to another through ships or even small
boats, and epizootics have been detected in them ; but rarely by means of
transport on land. The chances of an infected flea being carried from place to
place along with merchandise and even on man and his personal effects are
many. Fleas play far more important part in both retaining the infection and in
disseminating it than rats. The plague bacilli can survive for a much longer time
within the body of flea than is possible within that of the rat. When once they
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
enter the body of a rat, they either kill the rat when susceptible, and t'tus
get destroyed themselves or get exterminated in the body of an immune rat.
Evidently, the survival of plague organisms for a long time is only possible in :he
body of the rat-flea, and rats only provide facilities for maintaining tt eir
flourishing culture. Thus the flea is both a transmitter and a preserver of plague
infection, as pointed out by Golov and toff (1927) and Prince and Wayson
(b) Mechanism of Transmission
Some blood-sucking arthropods like bed-bugs and rodent lice, ticks and
mites, etc. (see Wu Lien-Teh et. al., 1936) are known to harbour plague
bacilli for a fairly long time ; but so far there is no conclusive evidence to slow
that any insect, except some fleas, is of any importance in the natt.ral
transmission of plague. Several methods of transmission were investigated by
the Advisory Committee (1906a, 1907a), of which the below-mentioned flour
methods by fleas were reinvestigated by subsequent workers.
(t) Ingestion of infected fleas by animals. -Most rodents scratch their body
with the teeth ; thus they accidentally eat or kill some of the infected fleas,
which affords an opportunity for the entry of plague organisms through the
abraded surface of their digestive tract. According to this mode there ii a
chance for some non-flea transmission.
(z) Mechanical infection.-Some workers (see Swellengrebel, 19:.3
Simmons and Hayes, 1948) claim that plague transmission by fleas is purel;.- a
mechanical process, and is effected by plague bacilli present on the probo: cis
of the infected fleas.
(3) Faecal infection is produced by the infested animal scratching or
ubbing faeces of the infected fleas into the irritable wounds made by the pro-
boscis of the fleas. This method of transmission was first suggested by Simond
(1898), and it was supported by the Advisory Committee. Bacot and Mai tin
(1914), however, showed that plague bacilli lose their virulence in the stom ich
of a flea, and only a few of them are passed in the faeces which soon dry up.
skey and Haas (1939) have demonstrated that it is not possible to ini ect
uineapigs by rubbing into the scarified skin both fresh or dry faeces of infected
leas. They, however, maintain that plague organisms can survive in diied
aeces for five weeks at the room temperature.
The above-mentioned three methods of plague transmission should lead us
o believe that every flea is equally an efficient vector ; but our knowledge of
pizootics and epidemics of plague is definitely against it.
(4) Regurgitation infection.-Bacot and Martin (1914) showed that plague
bacilli multiplied in such large masses in the interstices of the spines in the F ro-
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 ARGHTr Release 1999/09/10 : CIA-RDP83-00423RO01300270004-4
W
FLEAS AND THE PART THEY PLAY IN PLAGUL 119
The larval food appears to be an important factor that governs the
distributions and host preferences of different species of fleas. The larvae of
X. astia need the most nutritive diet. This species flourishes, if a rich larval
food is present in a rodent burrow, as in the burrows of Tatera indica and
Bandicota malabarica (Shaw), and even in those of the domestic rats in certain
regions, where their nesting conditions provide rich food for the flea larvae.
On the other hand, the nutritional requirements of the larvae of X. cheopis and
X. brasiliensis are simple ; thus they prosper readily in a burrow of the
domestic rat, even where the nutritive value of the larval food is very low, as
is the case in the plateaux of peninsular India, where jowari, bajri and
cotton are the main agricultural products. As the temperature tolerance
of X. brasiliensis (see page 17) is the lowest, this species is confined to some of
the cooler regions.
The irregular distribution of the three species of rat-fleas in the Indo-
Pakistan subcontinent may be related to differences in the nutritional value
of the varied organic substances found in rat burrows in different places.
The fact that the distribution of X. cheopis and X. brasiliensis is wider than
that of X. astia is attributed to the ability of their larvae to grow better on flour
alone ; this possibly enables them to survive transport in grain, even without
rats, to places far from their original home.
VI. ROLE OF FLEAS IN PLAGUE
Plague is primarily a disease of rodents, and man has become an incidental
victim. The earliest recognition of the causal connection between plague epizo-
otics and epidemics is probably indicated by the offerings, made by Philistines when
restoring the Ark they robbed from Cannan, which . consisted of golden images
of mice and of emerods or bubos [1 Samuel, v & vi]. Plague came to be
associated with man and merchandise in transit from plague infected areas
long ago, and from 1374 onwards measures of isolation and quarantine were
increasingly enforced for the control of the disease. The discovery of the
plague bacillusby Yersin and Kitasato in 1894 at Hong-Kong, was soon followed
by a hypothesis that fleas transmit plague organisms from rat to rat and from
rat to man by Ogata' (1897), Simond (1898), Gauthier and Raybaud (1903)
and Verjbitski (1904) proved experimentally that plague could be transmitted
from rat to rat by fleas. Liston (1905) and the Advisory Committee (1906a
1907a) definitely established the transmission of plague by the rat-flea.
From an epidemiological viewpoint Jorge (1928) distinguished between
the pandemic plague found in the domestic rodents, taking a very heavy toll of
human life all over the world, and the sylvatic plague found in the wild rodents,
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
FOURTH PAKISTAN SCIENCE CONFERENCE
only dangerous to man when he approaches the endemic areas.po`pulated b
wild rodents. Sylvatic plague has been reported from Transbaikalia, Mongclia
South-Eastern Russia, South Africa and the Western parts of the Unite
States of America. Plague at present is predominantly a disease of dome:'ti
rats, although originally it might have been acquired from wild rodents in 'h
course of evolution, when the association of rodents with human dwelli:ig
occurred. The study of sylvatic plague will . naturally lead to pro )e
understanding of the disease.
An active focus of sylvatic plague exists in the western parts of-U.S.A.,
and plague has been reported in the wild rodents of 138 counties of fifteen
western states (Link, 1951). Since 1934 extensive investigations are being'carr led
out under the supervision of the Sylvatic Plague Committee, and the reports of
the work done are published from time to time. Much has been added to our
knowledge of plague by these investigations (see Eskey and Haas, 1943).
Garnham (1949, p. 272) gives an account of the wild-rodent plague, end
according to him this type of plague " seems to have been accompanied by no
large-scale human epidemics ". History of the sylvatic plague in the South
Africa is given by Mitchell (1927) and Davis (1948).
(a) Preservation of the Plague Organism in Fleas
Plague is an acute infectious disease, and its .three important factors [re
the causative organism, Pasteurella pestis (Yersin), the rodent hosts and the
odent fleas, representing. respectively the fountain head, the perpetuating
force and the motive power in an unholy trinity. The plague epizootics and
epidemics depend on the interplay of these three factors in relation to the
climatic conditions. The bubonic plague is communicable as long as septicaen is
exists in the rodent host and a suitable flea vector is present.
The aetiological role of rodents has been definitely established ; bui: a
omplete harmony between the plague organism and any of its hosts has not
een achieved. The so-called cases of chronic plague amongst rodents have
een shown by the Advisory Committee (1906c, 1910a) to be stages of
rogressive recovery or " resolving plague " with entrenched infection at a site
ithout any bacteraemia. The rodents suffering from chronic plague infection
aturally will develop concomitant immunity, which thus cannot contribute to
he propagation of the disease.
The fact that epizootics are usually limited in extent and slow in the it
pread plays a very important part in the maintenance of plague amongst the
rolific breeding rodents. The factor responsible for the irregular distribution
f
l
p
ague in time is often considered to be seasonal incidence of fleas (site
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10: CIA-RDP83-00423R001300270004-4
FLEAS ANb TikE PART THEY PLA ' ItIT PLAbUE
More detailed and precise work on the effects of temperature and humidity
,on oviposition :and egg-hatching, especially in the case of rat-fleas, is highly
desirable, as their eggs are carried in grain merchandize from place to
place, and the only method of killing them is by exposing them to fatal
temperatures.
(c) Effects of Temperature and Humidity on Larvae and Pupae
Our knowledge of the bionomics of rat-fleas remained imperfect until
very recently. The larval diets used by several workers (see Sharif, 1949) for
rearing fleas had a poor and varied nutritive value, as is borne out by` high and
-variable mortality rates in their experiments. The food factor might have
influenced the results which are attributed to climatic conditions. For
ascertaining the effects of variations in temperature and humidity on the growth
rate of flea larvae and pupae, Sharif kept all other factors such as food, light,
soil and atmospheric pressure uniform in his experiments. Temperature
influences the developmental rate of flea larvae and pupae more than himidity.
The effective temperature range for the larvae varies according to the species,
being 12?-35.5?C. in X. brasiliensis, 12?-36.5?C. in X. cheopis and 13.5?-38?C.
in X. astia. The medial temperatures for their development varied from 17?-
29?C. in the first pecies, 17'-30?C. in the second and 23?-33.5?C. in the third,
The effective humidity range was much narrower in X. astia and slightly
wider in X. cheopis than in X. brasiliensis. The fact that the water balance of
the larvae of three species could only be maintained at 50 per cent and higher
relative humidities and their developmental rate was not affected materially
at a fairly wide range of favourable humidities suggests that the moisture
content of the debris affects directly the rearing of fleas and not the burrow
humidity above. For the normal breeding of flea larvae the presence of soil or
debris is very necessary.
Relative humidities higher than 90 per cent by themselves have no
deterring effect on the development of the early stages of fleas ; but their effect
on. flea breeding was mainly controlled by the amount of the -organic material
present in the sand or debris. When the sand was rich in organic material,
death of larvae and pupae occurred due to suffocation caused by the formation
of a crust and compact mass and by the sogginess of food and sand mixture ;
but it could be avoided by disturbing the mixture so as to allow free access of
air, to these stages. Sharif (1949) attributes the paucity of fleas observed in"
the burrows of Millardia meltada (Gray) and Gunomys koh (Gray) to the
presence of excessive moisture and debris rich in organic material, abundance
of fleas in those of Tatera indica (Hardwicke) to the absence of the first
factor alone, and moderate flea infestation generally found in those of domestic
rats to the absence of both these factors.
CPYRGHT
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
18
1OURTH PAKISTAN SCIENCE CONFERENCE
Sharif (1948b) proved that excessive loss of water in the flea larva
through its defecation and excretion as the result of absence of rectal glar.ds
through a profuse evaporation from the surface on account of its being a ,poi
inhabitant, and from its tracheal system owing to the absence of an effici en
closing apparatus of the spiracles, is compensated by the absorption of wate
with the food and through cuticle, and by the utilization of the metabolic wal er
(d) Nutritional Requirements of Larvae
Blood is considered as an integral part of the larval food for most fleas; but
Sharif (1937a, 1948a) showed that sterile dried blood alone was not sufBci~n
for the successful development of the rat-flea larvae, and so was yeast alone
The mixture of the two, however, gave almost hundred per cent success in ?h
rearing of fleas. As yeast possesses growth-promoting substances, .h
vitamins of the B group, it is considered that the native proteins of blood and
vitamins form an ideal food for flea larvae. Like some other insect larvae ;h
source of these vitamins (see Fraenkel and Blewett, 1943 ; Hobson, 1933, 1935
is micro-organisms like bacteria, fungi, etc., which synthesize them in the ford
Possibly the presence of plague bacilli in the faeces of adult fleas which tl.ei
larvae often eat help to explain, in part, the great number of fleas which have
been observed on rats in plague-infected houses (see Hirst, 1926).
The comparative nutritive value of dried horse blood, highly milled wheal
flour devoid of bran, mixed diets of blood and wheat flour and of blood -.n
yeast for the larvae of X. cheopis X. brasiliensis and X. astia was ascertailne
by Sharif (1948a). The growth of their larvae on wheat flour alone wa
erratic ; only partial success was obtained, and the adults emerged after lon
and irregular intervals owing to the association of micro-organisms, possibl
fungi, with this food. A mixture of blood and wheat flour accelerated tt e'
larval development ; but it was not as a satisfactory larval diet as blood z.n
yeast, the control. diet. Significant differences in the nutritional requirement
of the larvae of three species were observed. Advantage of these difference
was taken to account for the specific distribution and host preferences of these
species of rat-fleas in the Indo-Pakistan subcontinent.
Many species of fleas have become highly specialized not merely in reg lr
to the blood of a particular host, but as to its nesting conditions.. 1'h
conditions in the burrow make a great difference to larval nutrition z n
therefore to the absence, presence or abundance of fleas. The examination o
about 160,000 fleas of wild and domestic rodents of the Barsi and Dharwar talu ca
for about three years, and the study of their burrow conditions, have enabled t
ascertain some factors that control the irregular distribution of the three specie
of rat-fleas, which has a great bearing on the spread of plague.
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
The factors that can possibly control the variations in the population
f fleas are food, temperature, humidity, light, atmospheric pressure and the
iature of the soil. It is very essential to evaluate the effects of these factors
n flea populations individually at first and then collectively. Quantitative
ork of the type done by Buxton (1938, 1948), Leeson (1932, 1936), Sharif
1937a, 1948a & b, 1949), Smith (1951) and Edney (1945, 1947a & b) is
highly desirable.
(a) The Adult
The ecology of the adult fleas has not received so much attention that
it merits, owing to the important role they play in causing two of the
most. dreaded diseases of mankind, plague and typhus. As to their reaction
o the environmental conditions we know vary little. According to Chick
nd Martin (1911), X. cheopis and N. fasciatus, the rat-fleas, "when hungry,
eadily bite man". Hirst (1927a, p. 258) made observation on the biting
ropensity of the rat-fleas on man and rat, and found that "X. cheopis bites
an somewhat more readily than X. astia". Better controlled experiments
n the behaviour of adult fleas towards different climatic conditions and
heir biting habits are required, as from the standpoint of plague control
it is the psychology of fleas that matters.
(1) Longevity of unfed fleas.-As the rat-fleas are known to be carried
apart from their hosts in grain merchandise, personal effects, etc., their
ongevity in the unfed state is of a great interest from the plague viewpoint.
Bacot (1914) found that unfed fleas could live many days, a few specimens
of P. irritans survived for 125 days, of N. fasciatus for 95 days and of X. cheopis
for 38 days at 7.2?-10?C. with nearly saturated air : but at a higher temperature
of 26'7?C. or above with a humidity of 60 per cent or less they hardly
lived 10 days.
Earlier workers (Advisory,-Committee, 1908, 1912 ;Bacot, 1914 , Hirst,
1927x) have emphasized that high temperature and dryness, particularly the
latter, shorten the survival duration of rat-fleas. Leeson (1932, 1936) exposed
large numbers of adult X..cheopis of known age, some unfed, others fed once;
and others lived with a mouse one week to controlled temperatures and
humidities without any further feeding. Their survival duration was deter-
mined mainly.by temperature, being longer at lower temperature, and the
effect of humidity, though definite, was comparatively slight. Only at
lower effective temperature ,fleas lived longer at a higher humidity. He
established that survival of fleas was not proportional to saturation deficiency,
as was shown by, Bacot and Martin. (1924), Mellanby (1934) and Wig-
glesworth (1932, 1935), also have shown that the adult flea is nearly in-
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
FOURTH PAKISTAN SCIENCE CONFERENCE
different to humidity, even to a low humidity with high temperature. T.1 s
the adult flea as opposed to its . larva is capable of withstanding effect of
low humidity ; this according to Buxton (1938) is due to the adult being v' 1
protected against heavy loss of water by the presence of an efficient closing
mechanism of the spiracle and rectal glands, which is not the case
the larva.
(2) Longevity of the feeding adult fleas.-Bacot (1914) observed that .
irritans lived for more than 513 days, N. fasciatus for 106 days and X. chec p s
for 100 days, when fed on man. Unfortunately. Bacot kept these fleas t
a room temperature and humidity of Loughton in England, where the whit r
temperature is very low ; possibly the fleas were under the effect of CD] d
stupor, as Bacot's other experiments (Table LV, p, 627) kept at comparative y
better controlled temperatures show much shorter survival duration. Accord-
ing to Webster and Chitre (1930a), males and females of X. cheopis, w]Y n
entirely maintained on human blood, survived for 63 and 162 days respe -
tively at Bombay. Tiflov and Ioff (1932) in Russia were able to prolo g
the life of the suslik flea, feeding only once every 1-2 months, for ab At
five years.
Continually feeding adult fleas are even much less influenced by t e
humidity factor, as they can feed sufficiently to restore any loss of water which
a low humidity would cause (Buxton, 1938). It would be of a great importa I e
to ascertain the longevity of rat-fleas at different combinations of temperate e
and humidity. Furthermore, it would be necessary to determine the thresho d
of activity of rat-fleas, for exceptionally long life below 10?C. appears
be due to cold stupor. In this connection test-tube method of feeding fle s
will be very helpful, as the fleas are liable to be killed by experimental mice.
(b) Oviposition and Egg-hatching
We know very little about the precise conditions governing ovipositi n
and egg-hatching in fleas, in spite of the efforts of the Advisory Commits e
(1908, 1912), Bacot (1914), Hirst ('1927a), Webster (1930), and Hopla s
(1935) ; these workers only ascertained the effects of a few riot proper y
controlled temperatures and humidities on them. A flea lays eggs in batches
of less than 10 over a considerable period of time, punctuated by blood m~. s
which are necessary for their development. The hatching of eggs usu it y
occur after 2 to 10 days. According to Bacot, egg 'laying was advert e y
affected by the low temperatures and humidities, but in some species fertili y
increased at a low humidity, and 4.9?C. proved fatal to eggs of X. cheopis :t d
P. irritans but not to those of N. fasciatus. Webster (1930) found th t
eggs failed to hatch at 37? and 4.4?C.
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
FLEAS AND THE PART THEY PLAY IN PLAGUE
on the. presence or absence, respectively of a dorsal sulcus on the head,
which divides it into two parts. In actual practice the detection of this
groove in some cases is impossible. Jordan (fide Hubbard. 1947) and Ewing
(1929) are of opinion that there is no basic foundation for the creation of
these two sub-orders, and some workers have found the necessity of dividing
the fleas directly into families. Unfortunately, there is no general agreement
amongst the workers. on fleas as to the number and arrangement of their
families. Wagner (193)) recognized 10 families and 28 sub-families in addition
to many tribes of fleas. A satisfactory and natural classification is as
yet to be discovered. To put in the words of Hubbard (1947, p. 47), "Much
of the systematic work on fleas is unsatisfactory and many of the keys
so far developed are of little value."
The taxonomy of fleas is suffering from the usual disease of creation
of too many species by unexperienced workers and too much splitting which
may not be necessary : the latter has been regretted by Jordan. (1933). A
revision of the order in the form of a monograph on the fleas of the world
is greatly needed. Jordan (1925) notified once that he was engaged on a
"Monograph of the Siphonaptera" ; but unfortunately nothing material has
been done so far. According to Lima and Hathway (1946), there are over
1300 species and sub-species of fleas, and such a large number cannot be
managed by any one person, and a team of workers under the guidance of one
man will be able to achieve this end. Logically the work of revision of
the order should be done at the Tring Museum (England), where the largest
collection of fleas in the world is lodged.
V. ECOLOGY OF FLEAS
A fairly extensive literature exists on the life history and the biology
of fleas, and it has been reviewed by Sikes (1930) and Sharif (1937a, 1949).
Most of it deals with the rat-fleas ; the biology of most other fleas is practically.
an unexplored field.
Xenopsylla cheopis, X, astia Rothschild and X. brasiliensis (Baker), the
rat-fleas of the Indo-Pakistan subcontinent, are experimentally proved vectors
of plague (Webster and Chitre, 1930b), though their degree of efficiency as
vectors may vary. In view of their great medical importance, it is necessary
to ascertain the effects of different ecological factors on their reproduction,
rate of development and mortality, resultant population, behaviour, distribu-
tion in space and time, and host preferences. Though attempts have been'
made by previous workers (Advisory Committee, 1908, 1912 ; Bacot, 1914)
to determine the effects of some of .the. ecological-:.factors on these fleas, yet,
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
FOURTH PAKISTAN SCIENCE CONFERENCE
as pointed out by Hirst (1926) and Buxton (1938), our present knowledge of
their bionomics is incomplete.
The primary objects of the ecological studies should be to foresee, if
possible, to prevent flea abundance, and to elucidate the factors govern:ng
the fluctuations in the flea numbers. The correlation between outbreaks of
plague and flea abundance and geographical distribution of these three rat-flas
has been emphasized by many workers (see Advisory Committee, 19] 0 ;
Cragg, 1921, 1923). In order to assess the natural variability in populations
of these insects at a particular time and locality, several workers have mr de
use of the flea count, i.e. the number of fleas per rat ; this method, as point ed
out by Hirst (1926, 1927a) and Buxton (1938), is hardly suitable for the
purpose.
According to Hirst (19271b), the total rat-flea population of a gig en
premises is composed of three components : (1) fleas found on rats, i;2)
those present in their burrows, and (3) the free wandering fleas. Fleas do
not always live on rats ; a very large number of them remain in the debris or
litter of rat burrows, and a small proportion temporarily visit their hosts to
feed. There is not likely to be a fixed ratio between the number of &as
found on rats and those present in their burrows (see Leeson, 1936 ; Buxton,
1938). Fluctuations in the flea counts of domestic rats are influenced by the
state of hunger of the adult fleas and their behaviour towards the climatic
conditions at the time when the wandering rats are collected. The micro.
climate of rat burrow is often favourable for fleas, and thus most of them
remain in it, even when the outside atmospheric conditions are unbearable
for them (Buxton, 1932, 1933). In consequence, it is doubtful whether the
flea counts of wandering rats have any significance. Obtaining flea cen:,us
of burrows at different times may give an accurate estimate of the
variation in the flea population due to the climatic conditions ; but it is
beyond practical possibility, as is borne out by the attempts of Da ,pis
(1939).
It is, however, suggested that flea counts which have been our only
weapon, so far, for assessing the variability of flea populations due to clima tic
factors have failed us ; much time and energy have been wasted on them,
and many wild assumptions have been made without having any knowledge
of their exact significance. An accurate knowledge of the ecological factors
that govern the fluctuations of flea populations will be more useful. This
will also enable us to understand the real significance of the flea count, as
"the matter is important enough to demand study from a new angle, the
experimental, so that we may acquire knowledge of the limitations of this
widely used method" (Buxton, 1938, p. 528).
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
with that of mammals. The remains of the most ancient mammals have been
discovered in Asia, and fleas seem to have originated along with them. This
is borne out by the fact that there is a similarity between the North American
and East Asian fleas that are found on mammals which are considered to, have
migrated from East Asia into the North-America.
Without the necessary reliable record of the past, the links in the evolu-
tionary chain can only be deductions based mainly on comparative morphology
and embryology. Jordan (1950, p. 1) suggests `a partial reconstruction
of the ancestral flea' from what we know of the existing fleas will help ; but
comparative morphology can only be helpful if we can distinguish the generalized
types of structures from the specialized ones. Unfortunately, fleas as a group
are so highly specialized and their morphology so inadequately understood,
that many workers have laid stress on features whose very existence is a
matter of dispute ; consequently, the homologies of fleas would mock at.every
attempt.
Spines and excessive hairyness of fleas are adaptive features in accordance
with their being ectoparasites of .hairy mammals and feathery birds. This
would lead to the conclusion that less hairy fleas without spines, are more
primitive. A detailed morphology of such a flea, especially of Pariodontis
riggenbachi (Rothschild), will throw some light on the affinities of fleas.
The study of embryology of fleas like their comparative morphology has.
failed to explain the relationship of fleas with other insects. Kessel (1939,
p. 3), who gives a detailed account of the embryology of three species,
belonging to three different families of fleas, opines "it is inadvisable for
the writer to attempt a phylogenetic application of the present observations
until he has personally investigated the embryology of those forms which are
suspected of being most closely related to the Siphonaptera". Undoubtedly,
comparative embryological observations are , valuable in the solution of
phylogenetic problems; but it must be taken into cognizance that the em-
bryology of the fleas cannot differ fundamentally from that of the other
holometabolous insects. The differential characters of most holometabolous
orders are largely developed during the postembryonic life. In order to
ascertain the phylogeny of fleas one has to look to their postembryonic de
velopment especially during the pupal stage as pointed before (see p. 8).
Fleas are extremely specialized insects owing to their prolonged
parasitic association with mammals. They might have been very simple
holometabolous insects, probably in the Triassic period, but now they have
developed extremely specialized features which have masked their simplicity
beyond recognition. Fleas seem to have no close relationship with any of
the existing insect orders.. Probably they separated from the holometabolic
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
stock at a very early stage. According to Crampton (1931), fleas aiDne
are entitled to the rank of a superorder, the Pansiphonaptera, which is :one
of the three superorders into which he has divided all the holometabolous
insects. The other two are the Panmecoptera, containing the Neuropnra,
Mecoptera, Diptera, Lepidoptera, and Trichoptera, with their fossil al: ies,
and the Pancoleoptera, comprising the Coleoptera, Strepsiptera, and Hymeno-
ptera, with their fossil allies except the Protohymenoptera. His assumption
appears to be nearer the truth.
IV. SYSTEMATICS OF FLEAS
Linnaeus (1758) listed only two species of fleas. This . was followed by
scattered anatomical and systematic notes on fleas by Bosc (1801), Curtis
(1832), Duges (1832), Westwood (1838), Bouche (1835), Haliday (1856)
and others. Kolenati (1863) gave a systematic account of the fleas wl.ich
he divided into eight genera. Taschenberg (1880) recognized two 'families'
and five genera, comprising 33 species. Baker (1904) listed 135 specie: of
fleas then known in the world, which he divided into 5 families ; subsequently,
he. (1905) arranged them into 8 families. In the beginning of the present
century, the discovery that the plague bacillus is transmitted by f.eas
led to a serious study of their taxonomy. Amongst the workers
that have contributed largely to the systematics of fleas, the names of
Dampf, Wagner, Oudemans, Rothschild and Jordan deserve to be mentioned.
A catalogue of fleas of the world was published by Dalla Torree (1924). Of
the numerous papers published by Jordan and Rothschild, two papers (1906,
1908) are of a considerable interest. Wagner published a large number of
papers including four extremely valuable catalogues of fleas (1930, 1936b, 1938,
1939).
The taxonomy of the North American fleas has received a considerable
attention during the last fifteen years ; a number of monographic works by
Fox (1940), Ewing and Fox (1943), Hubbard (1947) and Holland (1949) .have
appeared. Jellison and Good (1942) prepared an "Index to the literature of
Siphonaptera of North America". Almeida Cunha (1914a and b) has described
the Brazilian fleas.
Over eighty species have been recorded from the Indo-Pakistan sub-
continent, and only a revision of the family Pulicidae was published by Sharif
(1930).
The order of fleas, for which three names, viz,, Suctoria, Aphanip:era
and Siphonaptera are being used, has been divided by Oudemans (19(19a)
into two sub-orders, Integricipita and Fracticinita :-this division is h.isod
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
ased on completely insufficient and defective interpretations of ihe'morphology
f fleas themselves'but also that of insects in general. During the last fifty
ears our knowledge of the morphology of insects has advanced considerably,
ut that of fleas has not kept pace with" it. Consequently, fleas still stand
solated among'the orders of holometabolous insects, and different attempts
o relate them with the other orders have failed for lack of sufficiently convinc-
ng evidence.
Martini (1922), who considers fleas having relationship with the Coleoptera,
ioints'out many similarities between fleas and the genus Oxytelus'be'longing to
he Staphylinoidea ; but these homologies as pointed out by Ewing and Fox
1943, p. 11) "are of a very general nature and doubtless exist between fleas and
` any other kinds of insects".
Crampton (1931), considers the Trichoptera as ancestors of fleas ;
or they have three-segmented labial palpi, and their prothoracic sclerites,
erci and male genitalia and the division of their mid- and hind-coxae into a
ucoxa and meron are similar to those of fleas. But Snodgrass (1946,
29) points out that the 'posterior part of coxa of fleas, called by Crampton
eron, has no anatomical identity with the meron of such insects as Mecop-
era, Trichoptera, and Lepidoptera" and that the male genitalia of , fleas are
nique. The true cerci are. absent in the fleas as shown by Ewing and Fox
1943). Till' and (1935, p. 39) attacked Crampton's theory very vehemently
or many reasons, and according to him "There is not a shred of evidence in
avour of Fleas having been derived from an aquatic ancestral type. Their
7hole life-history points to their having been derived from an ancestor which
ossessed a purely terrestrial- larva".
For a very long time many entomologists have held the view that fleas are
omewhat related to. the Diptera. . Packard (1894, p. 354) emphasized this
elationship greatly, ,for the "larva of the Siphonaptera apparently presents the
earest approach. of any, of.the insects now existing to the.shape of the priori-
ive Diptera", and for many other reasons. Dahl. (1893) derives the fleas' from
hypothetical stem the Archiscatopse, whose other living "representatives are
he nematocerus genus Scatopse and Phora. This is really. very speculative.,
van though Ewing and Fox ( 1943, p. 11) maintain that Dahl's "theory is one of
he best proposed, and he has given many data in support of it"
According to Tillyard (1935, p. 33), the Fleas cannot possibly have been
ascended from Diptera, for the obvious reason that the Fleas retain a complete
etathorax, whereas the Diptera, right from the earliest known types, have this
egment greatly reduced and incorporated with large mesothoracic mass, in
orrelation with loss of the hindwings". Previous to this Crampton (1931)
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
FOURTH PAKISTAN SCIENCE ' ONFEREt1UL
as also emphasized the importance of this evidence. The discovery of wing
uds on the mesothorax of pupae of three genera of fleas by Sharif (1935, 193''b)
it first sight would suggest the relationships of the fleas with the Diptera ; but
ccording to Snodgrass (1946, p. 20), "Ontogeny does not necessarily rep at
he whole ancestral story ; the presence of wing vestiges on the pupal me~o-
borax may represent in the fleas simply the last stage in the elimination of
he organs of flight that accompanied the evolution of the legs into organs for
jumping. The hind legs and the metathorax are the parts most highly modified
or leaping, so probably the metathoracic wings were the first to be lost, and are
not known to be recapitulated in ontogeny. The large size of the metathorax
in the fleas argues against the derivation of Siphonaptera from Diptera".
Tillyard (1935, p. 38) considers "the Fleas to, be a part of the Panorroid
Complex and that they must have been derived directly from Mecoplera
ather than from Diptera". His theory demands that the ancestors of f. eas
must have possessed short antennae, elongated mandibles, four-segmented
maxillary palpi, two-segmented labial palpi, a smooth and leathery body,
metathorax not highly reduced, middle and hind coxae with a meron, and a
terrestrial larva feeding on animal or vegetable debris, a free pupa either i:i a
cocoon or a primitive earthen cell. He (p. 43) believes that the only possible
ancestors that satisfy these conditions are "(a) a small, reduced type of pr:.mi-
tive Mecopteron, probably of the Upper Permian family Permochoristidae, or
(b) a related form classifiable definitely within the Paratrichoptera". It is,
however, difficult to agree with Tillyard, as there are numerous gaps tee be
bridged over in his theory.
The fleas are unknown in their primitive manifestations ; consequently,
their ancestry is wrapped in obscurity. The subject can only be approached
by the co-ordination of whatever evidence may be gleaned from three rrin-
cipal courts of appeal, palaeontology, comparative morphology and embry-
ology.
Of these, palaeontology has, so far, remained almost like a closed book.
The-oldest known fleas found in the Baltic amber belongs to the genus Paaeo-
psylla, which is very similar to the existing species of the same genus (Jordan,
1950). There is, however, an indirect evidence based on the palaeontology of
their fundamental hosts, the mammals. According to Holland (1949), fleas
originated in a remote geologic past as temporary ectoparasites of archaic small
mammals. They are even now predominantly ectoparasites of small mammnals,
but the transference of a few of their genera or species to birds seems to :lave
occurred at a much later period. Certain fleas have a preference for a par :icu-
lar genus or species of hosts. Fleas belonging to the family Ischnopsyllidae
are exclusive parasites of bats. Possibly the origin of fleas have some relation
Approved For Release 1999/09/10 : CIA-RDP83-00423 R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
FLEAS ANb THE PART THEY PLAY IN PLAGUE 7
exclusively formed by genital portions of the ninth and tenth sterna and cannot
be considered aedeagus. His earlier definition (Snodgrass, 1935, p. 621) of
endophallus, "The inner chamber of the pha"Jus invaginated at the end of
aedeagus" does not warrant the use of this term for a structure anterior to
the aedeagus. Snodgrass (1946, p. 58) has, however, made certain modifications
in the definition of endophallus, which only can be applicable to the structure
named by him "inner tube of aedeagus" ; the latter should have been designated
aedeagus as has been done by Jordan (1926). The basal apodeme of aedeagus is
nothing else but an apodeme of the genital portion of tenth abdominal sternum
as is elucidated by Sharif (1945). Undoubtedly, there is a little confusion about
the homology of some parts of the male genitalia ; but it can only be cleared by
the study of their post-embryonic development, especially during the pupal
stage.
(b) Internal Anatomy of the Adult
Amongst the earlier workers to whom we owe our knowledge of the
internal anatomy of the adult flea, the names of Karsten (1864), Landois (1866),
Bonnet (1867), Wagner (1889) and Packard (1894) deserve to be mentioned.
Lass (1905) mainly devoted his attention to the anatomy and post-embryonic
development of the female reproductive organs of the dog-flea. Advisory Com-
mittee (1906b) described the alimentary canal of Xenopsylla cheopis (Roths-
child).
Oudemans (1909b) and C. Fox (1914) pointed out the systematic value of
the spermatheca, and Dampf (1912) described the morphological significance
of ductus obturatorius. Cholodkovsky (1914) gave an account of the internal
male organs of reproduction and the rectum of the dog-flea.
For the most of what is known to us about the internal anatomy of the
adult flea, we are indebted to Patton and Cragg (1913), Patton and Evans
(1929) and Minchin..(1915).- Martini and Burgarth (1923) describe the internal
and external anatomy of the female -dog-flea with a view to ascertaining the
systematic position of fleas
Pavlovskij (1926) gives an illustrated account of the internal reproductive
organs of the males of six species. He found that individual genera showed'
articular differences in their reproductive organs. Faasch (1935) describes in
detail the alimentary canal and blood digestion in fleas.
Our knowledge of the internal anatomy of the adult flea is fragmentary
nd somewhat uncertain, and very few workers have gone even beyond describ-
ing the gross internal anatomy. Consequently, it is scarcely sufficiently detailed
to throw any light on the affinities of fleas with other insects. A more
detailed account of the internal anatomy of the adult is required.
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
FOURTH PAKISTAN SCIENCE CONFERENCE
(c) Anatomy of the Early Stages
Of the early stages of fleas, the larva seems to have attracted. the atten-
tion of many workers. Consequently, there exists a fairly extensive literature
on its morphology, covering a period of many years, most of which deals with
the external anatomy. It has been reviewed by Sharif (1937b), who gives a
detailed and illustrated account of the internal anatomy of the rat-flea larva in
the light of our existing knowledge of insect morphology. According to Iim
the wing buds are first formed in the prepupa, and are of the simple type as in
most Coleoptera,
Pupae have been briefly described by only a few workers (see Laboulbraee
1872 ; Bishopp, 1931 ; Elbel, 1951), mostly dealing' with the biology of fle as.
Both their figures and descriptions are such that they can be applied to ;i.ny
species of fleas. Sharif (1940), who examined the pupae of seven genera of
fleas, found that their sexes can easily be differentiated by the examination of
terminal segments, and even the pupae of different genera can readily be
distinguished by the configuration of these segments.
All fleas have free pupae which are completely unsclerotized, proba Sly
due to their being covered by well-spun cocoons.
Very little is known about the metamorphic changes that occur in he
third larval instar and the pupal stage. Heymons (1899) gave a short acco .Int
of the transformation of the mouth-parts of a flea, and his researches hive
greatly helped to elucidate the homologies of the mouth-parts of the ad.Ilt.
Wagner (1935,1936a ' ) described the changes undergone by the mid- and hi:id-
gut of Pulex irritans Linnaeus during metamorphosis.
Several years ago the author worked on the meta morphic changes in the
rat-flea, and a part of his investigations was incorporated in a previous publica-
tion (Sharif, 1937b), but a good deal of them has remained unpublished for
lack of time. These investigations have imprg,sed him that much valur ble
information about the affinities of fleas will be gained by this type of study,
as many of the adult pulicine peculiarities are only developed within the
pupa.
III. ORIGIN AND AFFINITIES OF FLEAS
Ever since the taxonomic study of insects started, the origin and the
affinities of the fleas have been debatable questions. Newman (1851), HalHay
(1856), Kraeplin (1884), Wagner (1889), Packard (1894), Dahl (1898), Heymons
(1899), Cholodkovsky (1914), Martini (1922), Martini and Burgarth (1923),
Crampton (1931) and Tillayard (1935) have devoted their attention to these
vexed problems. . The theories put forward by earlier workers were not only
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
portion is slightly directed forwards. The mesonotum does not show any
division into scutal and scutellar regions characteristic of the, tergum of many
wing bearing insects.
The metathorax of fleas is greatly developed owing to the part it plays in
relation to the jumping mechanism. The tergum is strengthened by a number
of internal apodemes, and pleura are "braced by well-developed ridges." The
metepimeron is greatly developed ; in some fleas it is the largest sclerite. It
occupies the lateral and ventral regions of the first abdominal segment, which
have no sclerotization of their own. It even overlaps the second abdominal
segment. The first abdominal spiracle lies underneath the metepimeron, and
according to Snodgrass (1946, p. 27), "It is difficult to explain the anatomical
confusion encountered here, except on the assumption that the spiracle has
retained its primitive abdominal position, and has been enveloped by the
expanding thoracic epimeron. .. An apparent reason for the great size of the
metathoracic epimeron is the presence of the large coxal muscle spread over
much of the epimeral wall."
Even though the structure of thoracic segments has elaborately been
described by Snodgrass (1946), Crampton (1931) and Fox (1941), still further
elucidation of their structure is. necessary. A detailed study of thoracic
musculature, hitherto undescribed, will undoubtedly throw more light on homo-
logies of the various thoracic sclerites and the affinities of fleas, as their thorax
has undergone the least modifications.
(3) The Abdomen.-Wagner (1932, 1933) has demonstrated, by an involved
argument, the presence of eleven abdominal segments in addition to the anal
segment in adult fleas ; but it has been shown by Ewing and Fox (1943), Sharif
(1945) and Snodgrass (1946) that the abdomen is composed of only ten
segments, and this number is easily discernible in the larval, pupal and adult
stages of fleas. Embryological studies of Kessel (1939, p. 44) on fleas show
the existence of eleven abdominal segments and the telson only in the early
embryo but the eleventh segment "is soon carried inward by the invagination
of the proctodaeum, and becomes telescoped within the tenth segment".
Possibly the so-called tenth abdominal segment in fleas is a composite structure
including' the eleventh segment.
The location of pygidium remains an open question. Most of the
workers (Jordan and Rothschild, 1906, 1908 ; Rothschild, 1915 ; Martini, 1922)
consider it as a part of the ninth tergum ; but Wagner (1932, 1933) assigned it
to the tenth, Sharif (1945) after refuting Wagner's arguments considers it
as a portion of the ninth tergum. Snodgrass (1946) identifies it as a part of
the tenth owing to the absence of any evidence of segmentation in the
pygidio-proctiger region. - Many workers have shown a line of demarcation
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
between the two, and Snodgrass has also observed it only in the male lea.
He (p. 40) considers the pygidial plate "merely an enlargement of the preccstal
area of a simple tergum". The pygidium should not be homologized with the
precosta of the following tenth segment, as the precosta can never be bigger
than its tergum ; while the pygidium is definitely so. According to Snodgrass
(p. 40), the dorsal pygidial muscles "are not present in female fleas", which nay
possibly account for the absence of division between the pygidium and proctiger
in the female. ]Evidently, the pygidium is a part of the ninth tergum.
The structure of female genitalia owing to its simplicity has been worked
out in detail by a number of workers (Lass, 1905 ; Martini and Burgarth, 1523 ;
Snodgrass, 1946) ; but according to Snodgrass very little is known about the
complex musculature of the bursa copulatrix and its duct, and the expuLory
mechanism of the spermatic apparatus. The homology of anal stylet.; is
unknown ; certainly, they are not cerci as is explained by Ewing and Fox
(1943).
The male genitalia is an extremely complicated structure, and accordint to
Snodgrass (1946, p. 3), "The complexity of the male intromittent: apparatus is
almost beyond belief". Sharif (1945) published a detailed account of the male
genitalia of Ctenocephal ides felis subsp. orientis (Jordan), about which Snodgrass
says (p. 60) In an elaborate study of the male genital organ of the oriental
cat flea, received too late for a full discussion, Sharif (1945) makes some eery
different interpretations from those given above. The external part of the
organ is regarded as an extension from the ninth and tenth abdominal sterna ;
the internal sack is therefore interpreted as a "phallothecal chamber", and
the inner tube as the true aedeagus. A sperm "pumping apparatus" is described
in detail, but no such structure has been observed, or, at least, so interpreted,
by the writer'. Snodgrass has homologized the claspers with parameres as is
the case in Mecoptera, Trichoptera and Nematocera ; but in fleas the clas:ers
have become united with the ninth abdominal tergum. This assumptior. he
bases on the description of formation of parameres in the prepupa of the rat.-flea
by Sharif (1937b) ; but in a later publication, Sharif (1945) suggests that
copulatory rods are probably the parameres. At this stage it is not pos.,ible
to agree with Snodgrass in considering claspers as parameres in view of our
limited knowledge of formation of these structures. Further researches are
required to elucidate this point.
According to Snodgrass (1946), the complex male apparatus consist,; of
the aedeagus bearing a large basal apodeme and endophallus. He has failed
to identify the periphallic structures with the ninth and tenth sterna, between
which the genital complex lies ; this has led to his different interpretation from
that of Sharif (1945). The structure identified by Snodgrass as aedeag is is
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
FLEAS AND THE PART THEY PLAY IN PLAGUE 3
oes not differ from the head of any other insect". This is also applicable to
orrectl
d h
Y.
any other structures of fleas, provided we can understan t em c
f fleas have attracted the attention of many workers (see
t
h
s o
-par
Lyl
out
andois, 1866; Packard, 1894, Heymons, 1899 , Advisory Committee 1906b;
nodgrass, 1944, 1946) ; but so far their homologies have been moot questions.
Of the three stylets of the mouth-parts, the unpaired one has been
esignated hypopharynx by Packard (1894), Ewing (1929) and Snodgrass(1944),
abrum by Heymons (1899) and Ewing and Fox (1943), labrum-epipharynx by
atton and Evans (1929) and epipharynx by Dampf (1945). Subsequently,
nodgrass (1946, p. 11) or. a reconsideration has named it correctly the epi-
harynx, and according to him "A similarly developed epipharyngeal structure
s not known to exist in any other insect". The ontogenetic studies on the
mouth-parts of Nosopsyllus fasciatus (Bosc) by Sharif (1937b), reveal that the
structure in question is the true epipharynx ; this fact was, however, not realised
by him when describing this structure. In the larva of this flea the epipharynx
is absent, and the labrum is well developed ; but in the third instar larva a bud
is formed at the junction of the lower surface of the labrum with the upper
surface of the buccal cavity, which outgrows the bud of the labrum. In the
prepupa and the pupa both the labrum and the epipharynx are present ; but the
latter has far outgrown the former, and the medial unpaired stylet of the adult
is formed within it.
The paired stylets have been regarded by Burner (1904) and by Snodgrass
(1944, 1946), as lacinae of the maxillae. According to Snodgrass (1946, p. 13),
the "articulation of the basal arms of the stylets on the lobes, and the origin
of the protractor muscles of the stylets...within the lobes can leave little doubt
that the stylets are the maxillary lacince". The study of the transverse sections
through the head by Sharif (1952) reveals that the basal arms of mandibles,
often called levers, do not articulate with the basal angles of the maxillary lobes,
as suggested by Snodgrass ; but only the distal ends of the levers are connected
with the maxillary lobes by the soft peristomal membrane which also connects
them with the labium. Only a part of the side of each lever lies embedded
in the peristomal membrane, and its greater portion lies within the cranial
capsule. The point of articulation between the basal arm of the mandible
and the maxilla, as is mentioned by Snodgrass (1944, 1946), is not possible ; for
the base of the lever lies inside the cranial capsule and the part of the maxilla
which according to him articulates with the lever lies outside it. The muscle
designated by Snodgrass as the protractor of the lacinia is in reality the
depressor of the galea. It is not possible to agree with Snodgrass (1944, p. 86)
in that the basal arms of the paired stylets of the flea "have neither of the two
usual mandibular articulations with the head, and, because of their position
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
FOURTH PAKISTAN SCIENCE CONFERENCE
between the maxillae, have no connection whatever with the cranial margin".
Each mandible has the two usual articulations with the head, one through t.:Ie
lever arm on the membranized peristomal fossa and the other through the inter
trabecula of the mandible below the free end of the hypopharynx.
The morphological significance of mouth-parts of the adult flea based )n
their ontogenetic development, partly described elsewhere (Sharif, 1937b) and
partly to be published shortly (Sharif, 1952), should leave no doubt as to the
mandibular nature of the paired stylets, as was suggested by most of the earlier
workers (see Heymons, 1899; Kraeplin, 1897; Jordan and Rothschild, 1906).
The large imaginal buds formed within the larval mandibles (see Sharif, 193"b,
Fig. 79) develop into mandibular lobes of the prepupa, having quite an inde-
pendent origin from those of the maxillae. Even the nerves supplying these
two kinds of lobes are different. Three distinct centres of proliferation of
ectodermal calls for the mandible, the maxilla and the labial palp close to ea,;h
side of the mouth should provide a convincing proof of the independent origin
of the mandible from that of the maxilla. Even at the time of adult formation
within the pupal skin the mandible has a distinct origin, as indicated by
distinct proliferation of its cells, from that of the maxilla. The forward move-
ment of the latter has commenced even in the pupa. The forward location of
the maxillae, a characteristic feature of fleas, their superimposition on the
mandibles, different interpretations of the musculature of the mandibles and
the maxillae, and wrong interpretation of mandibles as parts of maxillae by a
few'earlier workers have led Snodgrass to call them as lacinae. The presence or
absence of mandibles in the adult fleas is a very important: point for ascertaining
their affinities with other insects.
(2) The Thorax.-Fleas have lost their wings ; but they have utilized their
legs as an efficient substitute. The thorax of fleas is in many ways different
from that of the flying insects, from which they have certainly descended. The
sternal and pleural sclerites of each of the thoracic segments have becorr. e
fused ; though the apodomes on the inner side indicate the lines of demarcation
of the various component sclerites in many fleas.
The prothorax is composed of a tergum and a composite pleurosternal
plate. Owing to the complete fusion of sternum, episrernum and epimerum, it
is not possible to define the limits of these sclerites in fleas, although Snodgras
(1946) and Fox (1941) have suggested their approximate lines of demarcation.
The lateral compression of the head and the thorax has resulted in an unique
extreme forward extension of the junction of the pleurosternite and the first
pair of coxae ; the sternum is far ahead of the tergum.
The mesothorax has not got the pronounced angulation between the
tergum and the pleurosternal region found in the prothorax ; but still its sternzI
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
FLEAS AND THE PART THEY PLAY IN PLAGUE
SECTION OF
BIOLOGY: ZOOLOGY, ENTOMOLOGY AND BOTANY
PRESIDENT
Dr. M. SHARIF, D.Sc. (Panjab), Ph.D. (Cantab.), F.N.I., P.E.S. (I)
PROFESSOR OF ZOOLOGY, GOVERNMENT COLLEGE, LAHORE
PRESIDENTIAL ADDRESS
(Delivered on March z8, 1952)
CONTENTS
Pages
1. INTRODUCTION ... 1
II. MORPHOLOGY OF FLEAS ... 2
(a) External Anatomy of the Adult ... 2
(b) Internal Anatomy of the Adult ... 7
(c) Anatomy of the Early Stages ... 8
III. ORIGIN AND AFFINITIES OF
FLEAS 8
IV. SYSTEMATICS OF FLEAS ... 12
V. ECOLOGY OF FLEAS ... 13
(a) The Adult ... 15
(b) Oviposition and Egg-hatching ... 16
Pages
(c) Effects of Temperature and
Humidity on Larvae and Pupae... 17
(d) Nutritional Requirements of
Larvae ... IT
VI. ROLE OF FLEAS IN PLAGUE... " 19`
VII.
VIII.
(a) Preservation of the Plague Org-
anism in Fleas ... 20
(b) Mechanism of Transmission ... 22
(c) Spread of Plague and Endemic
Centres .... 24
CONCLUSION ... 26
REFERENCES 27'
1. INTRODUCTION
M MY first duty is to offer you my sincerest thanks for the honour you have.
conferred upon me by electing me to preside over the deliberations of the
section of biology this year. It has been customary for. the president to
address the section on a subject to which he has devoted some thought and.
study. I have been interested in fleas for the past .quarter'of a century, and.,
have, therefore, selected this subject for my address.. Fleas .are known to play.
an important part in the health, efficiency and comfort of a fairly large number of;
people throughout the world. The importance of fleas varies.from being a pure
nuisance to provoking flea allergy, plague, endemic typhus, tularemia, besides
playing an important role as pests of live-stock, dwellings and warehouses..
In these pages I have endeavoured to give an idea of. the. wo.r-k;that has,
been done on fleas and have indicated the lines of further research. My
intention is not to assume the role of a reviewer who must necessarily go
through all the details of the subject in the stereotyped manner, but to make an.
attempt to interpret.the many available publications, often conflicting, in the
light of my own observations and to try to evolve some order out of, the .seeming
r?hnns_ Owing to lack of time and space . it has not been possible' for me to deah
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
CPYRGHT
2 FOURTH PAKISTAN SCIENCE CONFERENCE
with some important aspects of this vast and complex subject, which embodi,'s
within its domain a huge store of information in the published form. My vast
and varied experience in the line in a way added to my difficulties in condensing
the remarks within the compass of a short address like this.
H. MORPHOLOGY OF FLEAS
Fleas are remarkable insects, as their morphology, in spite of the efforts :)f
many workers, has not been adequately understood. The lateral compression
of adult fleas necessary for their easy gliding through the hairs of mammals
and feathers of birds has caused many morphological complications. This fact,
often ignored, should be given due consideration in homologizing the various parts
of these insects. Further complications arise from their acquiring parasitic mode
of life in the remote past, when mammals, their fundamental hosts, first
appeared in the Triassic period. The dependence of fleas upon their hosts is
most marked, as they are the only holometabolous insects that need blood in
their feeding stages, the adult and the larva.
(a) External Anatomy of the Adult
We owe our knowledge of the external anatomy of the adult fleas `o
Karsten (1864), Landois (1866), Berte (1878), Wagner (1889, 1926), Rothschild
(1898), Tiraboschi (1904), Jordan and Rothschild (1906, 1908), Adviso:`y
Committee (1907b), Patton and Cragg (1913), and many others who only gi"~e
notes on the anatomy as applied to systematics.
A remarkable contribution to the anatomy of fleas has recently been made
by Snodgrass (1946, p. 3), who has attempted "to interpret the Skeletal anatomy
of fleas, according to the general principles of insect morphology"; but in
certain respects :fleas have even defied him : he was forced to say abo.it
their morphology that "there are numaroas peculiarities that strain the imagina-
tion for a plausible explanation". Owing to the extreme degree of specialization
of fleas, no part of their external anatomy could possibly be mistaken for that
of any other insect.
Our knowledge of flea morphology is far below the standard achiev,.d
in many other insects, even though after passing through series of errors com-
mitted one after the other, it has now taken somewhat correct shape. A de-
tailed anatomy of different adult fleas is still greatly needed to homologize the it
various parts.
(r) The Head.-According to Snodgrass (1946, p. 3). "The :head of fie
flea is a highly specialized cranial capsule, and most of its special features are
peculiar to the Siphonaptera ; but in its fundamental structure the flea heed
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 Approved For Release 1999/09/10 : CIA-RDP83-00423znn27nnna-A
PESHAWAR
17-22 MARCH, 1952
F O U R T H
PAKISTAN SCIENCE CONFERENCE
25X1A9a
FLEAS AND THE PART THEY PLAY IN PLAGUE
PRESIDENTIAL ADDRESS
BY
Dr. M. SHARIF, D.Sc. (Punjab), Ph.D. (Cantab.), F.N.L, P.E.S. (I)
PRESIDENT, SECTION OF
BIOLOGY : ZOOLOGY, ENTOMOLOGY AND BOTANY
/J1' :.. t;G~'' 't
PAKISTAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE
UNIVERSITY.INSTITUTE OF CHEMISTRY
L A H O R E
G'~ Approved For Release 1999/09/10 : CIA-RDP83-00423 R001300270004-4
 CPYRGHT
Experi-
Larval ments No. of
Species food used tried larvae used
B. 3 150
B. 4 178
W. 4 200
4 196
Astia W. 4 200
Cheopi8 B. and W. 3 160
Brasiliensis B. and W. 3 155
Astia B. and W. 4 182
Cheopis B. and Y. 3 170
Brasiliensis B. and Y. 4 204
Astia B. and Y. 2 85
Astia
Cheopis
No. of larvae and period
in which they completed
their active larval life
Days
Larval "
Species food used Larvae Range Mean
Cheopis B. 5 23-33 29.00
Cheopis W. 75 25-59 38.89 x
No.
145
160
Sig. t test
125 x x x
91 x x x
Brasilien8is W. 105 21-49 32.46 - x
Astia W. 52 44-80 6462 x x x
Cheopis B. and W. 160 13-21 15.22 x x x x r
Brasiliensis B. and W. 155 13-31 17.74 x x x x x
A8tia B. and W. 106 20-40 30.63 - x + x x x
Cheopis B. and Y. 170 8-13 10.92 x x x x x x x
Brasiliensis B. and Y. 202 10-14 11.95 x x x x x x x x
Astia B. and Y. 85 10-14 12.24 x x x x x x x x
Approved or Release 1999/0 -4
Table 1. Showing the effects of different foods, when mixed with acid-washed sand, on the growth of the recently hatched larvae
of the three Indian species of Xenopsylla at a temperature of 25 ? 1? C. and a relative humidity of 80 %
Larvae died in different active instars Larvae spun cocoons or formed naked pupae
Sig. t test
Sig. x2 test No. of No. of
------ cocoons naked pupae
No. of resting larvae and
period in which they
reached the adult stage
Length of females
Larval No. in mm.
food of -
Species used YY Range Mean
Cheopis B. 2 1.31-1.67 1.490
Cheopis W. 30 1.04-1.64 1.386 0.56-0.84
Cheopis B. and W. 27 1.27-1.91 1.575 - x 4 0.67-0.89
Cheopis B. and Y. 61 1.76-2.24 1.952 x x x 0.84-1.04
Brasiliensis W. 31 1.09-1.49 1.320 + + x x 0.58-0.71
Brasiliensis B. and W. 9 1.25-1.42 1.346 - - x x - 0.53-0.67
Brasiliensis B. and Y. 87 1.48-1.88 1.688 x x x x x x 0.72-1.00
Astia W. 30 1.24-1.49 1.355 + - x x - - R 0 58-0 75
Astia B. and W. 17 1.27-1.91 1.554 - x - x x x x x 0.67-0.89
Astia B. and Y. 51 1.76-2.16 1.962 x x x - x x x x x 0-92-1-16
Breadth of females
in mm.
Range
0.58-0.62
Mean
0.600
148 x x x+ x
0 x x x x x x
0 x x x x x x- T 0
76 X X X X- X X X 3
Days
Resting ,- - Sig. t test
larvae Range Mean ,-----~---
5 12-18 13.80 -f
54 14-26 19.61 x fi
84 13-24 17.13 x x
34 13-17 15.00 - x x +
15 15-19 17.60 x + - - x t
44 10-17 13.91 - x x x + x
164 11-17 13.28 - x x x x x
197 11-18 14.35 - x x x - x
85 11-17 13.40 - x x x x x
t
0.699
0.788 x x t
0.950 x x x
0.643 - x x x t
0.614 - x x x +
0.664 + + x x + x x
Sig. t test
T
105 x x x x f
52 x x x+ x t
87 x x x x- x t
75 x x x-- x- f
f
168 x x x x x x x x x
202 x x x x x x x x x
85 x x x x x x x x x
Table 2. Showing the effects of different foods, when mixed with acid-washed sand, on the growth of the recently hatched larvae of the three
Indian species of Xenopsylla at a temperature of 25? 1? C. and a relative humidity of 80 %
No. of females and duration
of their combined larval
and pupal life
Days
4? Range Mean
2 44-45 44.50
f
T
54 X X X
Sig. t test
49 34-62 46.00 - x T
30 60-112 80.17 x x x
27 26-33 28.89 x x x x
9 31-38 33.00 x x x x
29 33-48 40.48 - x x x
83 19-23 21-28 x x x x
107 21-26 23-08 x x x x
Table 3. Showing the measurements of adults of the three Indian species of Xenopsylla reared from larvae fed on different foods, when mixed
with acid-washed sand, at a temperature of 25 ? 1 ? C. and a relative humidity of 80 %
Length of males
No. in mm.
of Sig. t test
dd Range Mean ,----- -
3 1-35-1-67 1.490
t
7 1.44-1.84 1.630 - x
61 1.80-2.12 1.964 x x x
30 1.05-1.73 1.325 +
6 1.09-1.42 1-295 - - x x -
67 1.52-1.88 1.678 x x - x x x
11 1.24-1.55 1??400 - - x x -
15 1.20-1.91 1-549 - x - x x x x
34 1.84-2.12 1.968 x x x - x x x
Key to abbreviations: B., blood; B. and W., blood and wheat flour; B. and Y., blood and yeast; W., wheat flour;
Sig. t test, t test of significance; Sig, x2 test, x2 test of significance; -, not significant; +, significant at 5 % level;
x, significant at 1 % level.
X X
No. Sig. x2 test
41 x x x- x r
34 x x x- x I f
15 + x x x x x x f
44 X X X- x-- X
X x x
T 197 x x x x x x x x x
No. of males and duration
of their combined larval
and pupal life
Days
dd Range Mean
3 40-44 41.67
16 45-65 58.06 x
35 39-65 49.57 + x
11 68-85 76.45
7 26-33 32-00 x x x
6 28-40 32.50 + x x x
15 37-54 42.40 - x x x x
81 25-29 27-11 x x x x x x x f
90 28-32 29.87 x x x x x x x x
34 28-31 29-47 x x x x x x x x
Breadth of males
in rum.
Range Mean
0.58-0.62 0-593
0.56-0.69 0-628
0.58-0.87 0-717
0-53-0-75 0-587
0.58-0.69 0.637
0.76-0.96 0.814 x x
0.53-0.76 0.615 - - + x - - x
0-62-0-87 0.720 x x - x x + x x f
0.76-0.92 0.859 x x x
+ +
X X X f
Sig. t test
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4
 CPYRGHT
Approved For Releetse
M. SHARIF
indebtedness to Dr K. A. Gandhi, Director of Public
Health for the Government of Bombay, for full co-
operation in administrative matters and to the
Government of Bombay for financial aid in con-
ducting my inquiry. Messrs K. D. Gumaste, T. N.
Raste and P. M. Salvekar -have helped me in the
compilation and calculation of the data statistically,
and I am pleased to record my obligation to them.
I am grateful to Dr W. J. Martin for advice in
statistical matters.
ADVISORY COMMITTEE (1907a). J. Hyg., Camb., 7,
395-420.
ADVISORY COMMITTEE (1907b). J. Hyg., Cannb., 7,
436-45.
ADVISORY COMMITTEE (1908). J. Hyg., Camb., 8,
236-59.
BACOT, A. (1914). J. Hyg., Camb., Plague Supplement,
3, 447-654.
BLEWETT, M. & FRAENKEL, G. (1944). Proc. Roy. Soc.
B, 132, 212-21.
BREOHER, G. & WIGGLEBWORTII, V. B. (1941). Para-
sitology, 35, 220-4.
BUXTON, P. A. (1932). Indian J. Med. Res. 20, 281-97.
BUXTON, P. A. (1937). Brit. Mus. (Nat. Hist.) Econ. Ser.
No. 3, 4th ed., pp. 1-20. London.
BUXTON, P. A. (1941). Bull. Ent. Res. 32, 119-22.
BUXTON, P. A. & MFLLANBY, K. (1934). Bull. Ent. Res.
25, 171-5.
CHAPMAN, R. N. (1931). Animal Ecology. New York.
CRAGG, F. W. (1921). Indian J. Med. Res. 9, 374-98.
CRAGG, F. W. (1923). Indian J. Med. Res. 10, 953-61.
FISHER, R. A. (1941). Statistical Methods for Research
Workers, 8th ed. Edinburgh and London.
FISHER, R. A. & YATES, F. (1943). Statistical Tables for
Biological, Agricultural and Medical Research, 2nd ed.
London and Edinburgh.
FRAENKEL, G. & BLEWETT, M. (1943a). Nature, Lend.,
152,506-7.
FRAENKEL, G. & BLEWETT, M. (1943b). Trans. Roy. Ent.
Soc. Lond. 93, 457-90.
HIRST, L. F. (1923). Indian J. Med. Res. 10, 789-820.
HIRST, L. F. (1925). J. Hyg., Camb., 24, 1-16.
HIRST, L. F. (1926). Ceylon J. Sci. (Sect. D), 1, 155-271.
HIRST, L. F. (1927a). Ceylon J. Sci. (Sect. D), 1, 277-455.
HIRST, L. F. (1927b). Trans. R. Soc. Trop. Med. Hyg. 21,
87-104.
HIRST, L. F. (1933). Ceylon J. Sri. (Sect. D), 3, 49-113.
HOBSON, R. P. (1933). Biochem. J. 27, 1899-1909.
HossoN, R. P. (1935). Biochem. J. 29, 1286-91.
IYER, P. V. S. (1933). ,Indian J. Med. Res. 20, 975-94.
JOLLY, G. G., FENN, V. W. & DoRAI, R. (1931). Indian
J. Med. Res. 18, 1231-44.
KING, H. H. & PANDIT, C. G. (1931). Indian J. Med.
Res. 19, 357-92.
LEESON, H. S. (1932). Bull. Ent. Res. 23, 25-31.
LEEwENIIOrcK, A. (1683). Philos. Trans. 13, No. 145
74-81.
McCARRisoN, R. (1927). Indian J. Med. Res. 14,
631-9.
PATTON, W. S. & EVANS, A. M. (1929). Insects, Ticks,
Mites and Venomous Animals of Medical and Veteri-
nary Importance, Part I. Croydon.
SRARIF, M. (1930). Rec. Indian Mus. 32, 29-62.
SHARIF, M. (1937). Parasitology, 29, 225-38.
SHARIF, M. (1948). Effects of constant temperature and
humidity on the development of the larvae and the
pupae of the three Indian species of Xenopsylla
(Siphonaptera). [In the Press.]
SIIELFORD, V. E. (1930). Laboratory and Field Ecology,
2nd ed. Baltimore.
SIXES, E. K. (1931). Parasitology, 23, 243-9.
TAYLOR, J. & CUITRE, G. D. (1923). Indian J. Med. Res.
11, 621-38.
WEBSTER, W. J. (1930). Indian J. Med. Res. 18, 391-
405.
WEBSTER, W.J. & CRITRE, G. D. (1930). Indian J. Med.
Res. 17, 699-709.
WIGGLrswORTII, V. B. (1936). Parasitology, 28, 284-9.
(MS. received for publication 15. iv. 1946.-Ed.)
Approved For Release 1999/09/10 : CIA-RDP83-00423R001300270004-4