Cattle-Hypooerma Lineatum Animal Systemic Insecticide Test, 1981

Abstract

Abstract Government-owned Hereford and Angus yearlings on pasture at Camp Stanley and Camp Builis, Bexar Co., TX, that are naturally infested with the common cattle grub, Hypodermalineatum (Villers), are treated with new insecticides that were detected to be systemically active in the mouse-Cuterebra animal systemic insecticide test. Animals are weighed and given insecticides in initial tests either orally by capsule (usually technical grade insecticide) or dermally by whole-body spray of 4 liters/animal at greater than 150 psi (usually formulated as an EC in xylene (65 parts), Triton x-100 (10 parts), and ai (25 parts). In other tests, insecticides labeled for use as systemic treatments for cattle grub control may be administered dermally to calves by pouron of a specific volume of insecticide (usually water-diluted EC as above or solution in oil) per body weight or intramuscularly by injection of a specific weight of insecticide (usually technical grade insecticide in diethyl succinate) per body weight. Normally cattle are treated with new insecticides initially at the highest nonlethal dosages as determined by cooperating veterinary toxicologists; maximum dosages of initial tests are 100 mg/kg orally and 1% spray. Occasionally cattle are treated with titrated dosages of labeled systemics in order to determine systemic activity of dosages less than label-tested dosages. After the treatment in May or Jun, the backs of treated cattle (usually 3-5 animals/treatment) and untreated cattle of the same age and breed from the same herd are examined monthly from Aug to Feb of the next year for encapsulated cattle grubs. As cattle grubs appear, they are located on an outline map of the back of each animal; the cumulative number of grubs in each animal is obtained. Effectiveness of a treatment is determined by comparing the average number of grubs in treated cattle with the average number in untreated cattle. The most recent report of tests with systemics for control of cattle grubs in cattle was presented by Drummond, R. 0., 1981, Insect, and Acaric. Tests 6:188.