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INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY
[VOL. XXIX, PART I
0.15 per cent BHC. Batte and Gaines [1948] working on the control of D. equi, found that chlor-
dane wettable powder was more effective than DDT wettable powder at concentration above
0.075 per cent. LD50 of chlordane emulsion, chlordane wettable powder and DDT wet-
table powder were found to be 0.043± 0.001, 0.06±0.001 and 0.099±0.001 respectively.
Smith and Richards [1955] reported that 100 per cent initial control of H. eurysternus was ob-
tained with 0.25 per cent DDT, 0.5 per cent toxaphene, 0.05 per cent malathion and 0.05
per cent diazinon and the treated cattle remained louse-free for 3, 4, 1 and 1 week respectively;
0.5 per cent DDT, 0.5 per cent malathion and 0.25 per cent diazinon treatments gave comp-
lete protection to cattle for 4, 2 and 2 weeks respectively. Similarly, 0.25 per cent DDT, 0.025
per cent malathion and 0.005 per cent diazinon gave 100 per cent initial kill (in 24 hours) of
goat lice D. caprae and D. limbatus and no louse was found on the goat, thus treated, at least
for four weeks except in those treated with the diazinon treatment, in which light infestation
was found when examined four weeks after treatment.
Though some information is available on the efficacy of some chlorinated hydrocarbon
insecticides (mostly DDT and BHC) on the control of lice infesting livestock, records relating
to the results of trials with organic phosphate insecticides in this connection are not many. Be-
sides, no record is available on the subject relating to the conditions in this country. A series of
semi-field trials were, therefore, conducted during 1956 at the Indian Veterinary Research
Institute, Izatnagar, to ascertain the efficacy of a number of modern insecticides, both chlori-
nated hydrocarbons and organic phosphates, on the control of lice infestation on some of the
livestock under the conditions obtaining in this country. It should be mentioned here that
since these were pilot trials and sufficient numbers of animals could not be used in them, the
results cannot necessarily be taken as conclusive. Nevertheless, these trials have given much
valuable information, which are essential for carrying out the detailed trials on the problem.
The results, therefore, are presented here in the hope that they will be taken as a basis for carry-
ing" out more detailed trials for evaluating the insecticides against livestock lice in the field con-
dition of this country.
MATERIAL AND METHODS
In the Izatnagar area where these trials were conducted, buffaloes and cow calves were
found to be infested with lice Haematopinus tuberculatus Burn, and Linognathus vituli L. respec-
tively ; goats were infested with two species of lice, namely L. stenopsis Burn, and Damalinia
caprae Gum. In the case of buffalo calves and cow calves their neck and flank are more in-
fested by these lice than other parts of their body. As regards the lice infesting goats, D. caprae
(biting lice) are mostly found on the long haired regions of the hind legs and back of the goat
whereas L. stenopsis (sucking lice) remains confined mostly to the neck and shoulder regions of the
goat when the infestation is not heavy. When the infestation is heavy, lice are found more or
less all over the body of the host. Lice infested buffalo calves, cow calves and goats were used as
experimental animals in these trials against their respective louse parasites. DDT, lindane,
toxaphene, rhothane, chlordane, aldrin, dieldrin, malathion and diazinon were the different
modern insecticides that had been tested. However, as will be seen later, it was not possible
to use all these insecticides against each species of the lice. Except malathion (emulsifiable
liquid) all the insecticides used were wettable powders. Treatments were applied on the animals
as wash daubing with the help of cotton wads so as to wet the body of the treated animals
thoroughly with the liquid. Evaluation of the efficacy of the insecticides in controlling the lice
has been done on the basis of the number of lice present on the body of the treated animals
after different periods from the time of application. The lice population on each experimental
animal 24 hours before treatment was also recorded. After the application of the treatments,
in most cases, the animals were kept apart from other untreated animals for a few days and
afterwards they were allowed to mix together with the latter.
RESULTS
Trials against buffalo louse (Haematopinus tuberculatus)
For this trial nine buffalo calves infested with the louse H. tuberculatus were selected. Some