Rich, G. B.

English

Journal of the Entomological Society of British Columbia

58 ENTOMOLOGICAL SOCIETY OF BRITISH COLUMBIA, PROC. (1951), VOL. 48, AUG. 15, 1952 clusters of ten to 50 ticks and it is doubtful whether these animals could be paralysed by solitary specimens. However, not all animals with heavy infestations will become paralysed -suggesting again an individual re-sistance. The data for lambs 10, 13, 14, 18, and 19 substantiate a variation in virulence among ticks. At the same time, there is an indication that a paralysed animal is so weakened that it may then be affected by ticks, which on a healthy animal, would not be considered virulent. This is evident in animals on the range which often remain prostrate for several hours until the las t ticks are removed, and then make a rapid recovery. This could be the case in lamb 13. Lamb 9 presented an interesting op-portunity for a further experiment in that paralysis commenced when the two engorging ticks were only half-replete. The ticks were transferred to lamb 1, which, though having been subjected to ticks, had not yet been paralysed. The virulent ticks attach-ed, and dropped within a day-but did not cause paralysis. Similar re-sults occurred in a previous year when a partially fed tick from a paralysed child was induced to attach to a mouse, whereupon it mated and fed rapidly without harm to its second host. Again there are too many unknowns to establish a reason for this behav-iour. It appears that a virulent tick can paralyse only the host upon which it commences to engorge. In summary, it is assumed that tick paralysis is brought about in the host by a toxin secreted by the engorging tick. It appears that the production of tick paralysis in an animal depends on a combination of host sus ceptibility and tick virulence; and that where the host is relatively resistant, as in sheep and cat tie, only a certain por-tion ot rapidly feeding ticks produce the symptoms, whereas in humans, considered to be more susceptible, solitary, slow-fe ~ding ticks are suffi-cient to cause paralysis. The conflict-ing evidence concerning the va rying resistance of the host and the unknown virulence of the ticks makes it difficult to arrive at any conclusion. Referencea Gregson, ]. D. 1944. The influence of Zumpt, F., and D. Gl ajchen. 1950. South fertility on the feedin g rate of the female African Merl. J. 25 :1092-1094. o f the wood tick, Dermacentor andersoni Stiles. 74th Ann. Rept. Ent. Soc. Ont., 1943, pp. 46-47. A REVIEW OF STUDIES ON THE SYSTEMIC CONTROL OF LIVESTOCK INSECT PARASITESl G. B. RrCH2 Livestock Insect Laboratory, Kamloops, B.C. If, without causing harm to the animals, it were possible for a stock-man to introduce into the diet of his livestock some substance that was toxic to bloodsucking arthropods feeding' upon these animals, he would find a solution to one of the important problems of animal husbandry. Eco-nomic entomologists have recently devoted a great deal of effort toward the attainment of this ideal, and the 1 Contribution No. 2912. Division of Entomology, Science Service, ])epartm.ent of Agriculture, Ottawa, Canada; presented at the ':Oth Anniversarv h-ieetings of the Entomologic:1l Society of Briti sh Columbia ill Vancouver, June' 14·16, 1951. 2 Assistant En tomologis t. investigations seem to indicate that it may be possible to achieve it. However, the problem is no t simple. Many difficult biochemical and toxi-cological factors must be studied and their roles elucidated before the prob-lem can be solved. Because of these factors, the entire matter must be ap-proached with caution. A full dis-cussion of these aspects is beyond the scope of this paper because it is my intention only to review som e of the more important studies that have been made in the past. The first important contribution is that of Knipling (1938), who reported ENTOMOLOGICAL SOCIETY OF BRITISH COLUMBIA, PROC. (1951), VOL. 48, AUG. 15, 1952 59 that, when cattle ingested phenothia-zine, horn fly larvae did not develop in the manure subsequently eliminat-ed by such animals. Bruce (1939) confirmed these findings and estab-lished the dosage levels required for maximum control. Creighton (1943) made an unsuccessful attempt to con-trol chicken lice by adding sulphur to the concentrate portion of the poultry diet. The recognition of the insecticidal properties of DDT and EHC institut-ed widespread investigations of the insecticidal properties of many organ-ic chemicals, and the systemic aspect was not neglected. Linquest (1944) reported that oral ingestion by rabbits of either DDT or pyrethrum in mas-sive dosages was toxic to bed bugs subsequently fed on the rabbits. de Meillon (1946) made a similar observa-tion concerning the bed bug feeding on rabbits that had ingested the gam-ma isomer of EHe. This observation was confirmed by Wilson (1948), who administered it orallv as a control for tsetse flies on cattle: J. D. Gregson (personal communi-cation) noted that ingested gamma isomer of EHC was toxic to ticks and lice feeding on horses, cattle, and chickens. This observation, together with the published data of deMeillon and Wilson, provided the basis for an extensive series of tests conducted at the Kamloops laboratory in the sum-mer of 1949. During that summer I carried out a test of the gamma isomer of BHC, using domestic hogs and their natural parasite, Haematopinus suis (Linn.), as experimental animals. Single dosages at the level of 40 milligrams per kilo-gram of animal body weight provided 100 per cent. control of the parasite for about eight to ten days. Daily dosages at the level of 20 milligrams per kilogram for four days were re-quired to produce similar results. However, a series of toxicity tests, with guinea pigs as the test animals, showed that daily treatment at dosage levels of 20 milligrams per kilogram was a dangerous practice. It is per-haps invalid to extend experimental results determined with one animal species to other, dissimilar species; but sinc,~ it is economically impossible to conduct satisfactory toxicity tests with animals such as cattle, horses, and hogs, it was decided that in this instance the extension was justifiable. Therefore these tests were considered to have indicated that this treatment was not a valid control method. In the meantime other workers had conducted preliminary tests with many other chemicals. Knipling (1948) published the results of an extensive series of tests involving many differ-ent chemical compounds in an attempt to control the body louse, Pediculus humantlJ corporis Deg., feeding on rab-bits. The most promising of the com-pounds tested was 2-pivalyl-1, 3-indan-dione. Babers (1949) published a fa-vourable report of tests conducterl with this chemical, using the same experimental animals. This review of the systemic aspect of livestock parasite control is brief; however, it indicates that the problem is not being neglected and suggests a concrete basis for its solution. References Babers, F. H ., and G. H. Culpepper. 1949. The effects of 2-pivalyl-l, 3-indandione on body lice when administered orally to rab-bit hosts. J. parasitology 35 :551-554. Bruce, W. G. 1939. The use of phenothia-zine in the modification of cattle for the control of horn flies. J. Econ. Ent. 32: 704-706. Creighton, J. F., G. W. Dekle and Jack Russell. 1943. The use of sulfur and sul-fur compounds in the control of poultry lice. J. Econ. Ent. 36 :413-419. de Meillon, B. 1946. Effect on some blood-sucking arthropods of Gammexane when fed to a rabbit. Nature 158 :839. Knipling, E. F. 1938. Internal treatment of animals with phenothiazine to prevent development of horn fiy larvae in the manure. J Econ. Ent. 31 :315-316. -1948. Evaluation of selected insecti-cides and drugs as chemotherapeutic agents against external bloodsucking para-sites. J. Parasitology 34 :55-70. Lindquist, A. W., E. F. Knipling, Howard A. Jones, and A. H. Madden. 1944. Mortal-ity of bedbugs on rabbits given oral dos-ages of DDT and pyrethrum. J. Econ. Ent. 37 :128. Wilson, S. G. 1948. The effect on ticks and Glossina of feeding cattle on BHC or DDT. Blull. Ent. Res. 39 :423-434. 

A review of studies of the systemic control of livestock insect parasites

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A review of studies of the systemic control of livestock insect parasites

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Journal of the Entomological Society of British Columbia