The efficiency of 2-cyclopropylamino-4, 6-diamino-s-triazine CGA-72662 (proposed common name: cyromazine) for the control of blowfly strike was tested in fly cage and field trials on sheep. The safety to sheep and physico-chemical properties of the compound as they relate to blowfly control were also assessed. When the sheep were thoroughly jetted with a solution of CGA-72662 containing 1g of active ingredient per litre, the mean incidence of fly strike in 7 field trials was reduced from 16.5% to 1.5% over a period of 9 weeks. The incidence of strike in the treated sheep in 2 insectary tests, which imposed levels of fly activity far in excess of that usually encountered in the field, was reduced from 93% and 73% in untreated sheep to 2% and nil respectively over a period of 8 weeks. Jetting with CGA-72662 solutions 100 times greater than the recommended concentration did not produce any side effects in sheep. Three treatments at twice the recommended concentration during the first trimester did not affect pregnant ewes nor their progeny. The compound was safe to use in combination with common anthelmintics and with sheep dips used for control of lice. CGA-72662 was stable in solution. No stripping occurred in dips and it persisted on wool for a considerable period. A satisfactory alternative to the organophosphorus insecticides has been found in CGA-72662, since it provided a substantial increase in residual protection against blowfly strike with a high degree of safety.
Procedures are described for rearing Haemarobia irrirans exigua using a bull as host for the adult flies and an artificial medium for rearing the larvae.The buffalo fly, Haematobia irritans exigua de Meijere, is morphologically very similar to the horn fly, Haematobia irritans irritans (L.), yet it has not been colonised successfully. Attempts to colonise the hornfly were first reported by Glaser (1923Glaser ( , 1924. Depner (1962) maintained adult flies on cattle in screened cages and reared the larvae in cattle faeces. Harris (1962) maintained a colony of horn flies that reproduced without contact with a host animal and subsequently, Bay and Harris (1978) reported that they had maintained a colony in the laboratory for 3 years. Mass rearing of horn flies was undertaken by Miller et a/. (1979).In 1979 we attempted to rear H. irritans exigua in order to provide a supply of standard-age flies to evaluate the persistency of chemicals on treated cattle. All horn fly rearing methods proved unsuccessful. The buffalo fly rearing system reported here separates the feeding flies and the breeding cycle completely.A young Polled Hereford bull was kept in a totally enclosed pen (2 x 2.5 x 3.5 m) with a steel mesh floor supported ca 0.3 m above a slopingconcrete floor. All daylight was excluded since natural light attracts the flies. A darkened entrance helped to reduce the loss of buffalo flies and the entry of unwanted insects. Continuous lighting was provided by a 40 watt fluorescent tube with a light-diffusingcover cuO.25 m above the bull. Temperature was maintained above 26°C (30°C max) using a small thermostaticallycontrolled fan heater. The pen was continually ventilated using an extractor fan which removed ammonia generated from the bull urine. When ammonia was present flies rested on the ceiling instead of resting on the bull. Humidity was kept high by flushing the floor with water frequentlyduring theday. All dung was hosed away twiceeach day.The bull, which was confined to 1 side of the pen by rails and tethered slackly, had continuous access to fresh water and lucerne chaff supplemented once a day with cattle pellets. The bull was groomed regularly with a wire brush to remove scurf, small scabs and fly excreta. Continuous exposure ca 10 OOO flies was tolerated well for periods exceeding I month.Initially ca 10 OOO flies were caught off yarded cattle using a collecting net and used to stock the pen.Caught flies were transported to the laboratory in cages (8 x 8 x 8 cm) made from plasticcoated wire covered with a nylon stocking. Wet cloths or moistened sponges were placed below and over the cage to maintain high humidity. If humidity was low most flies died within 30 minutes.
SummaryAn account is given of comparative trials in which dips containing arsenic, BHC, aldrin, and dieldrin were used. At the minimum concentrations used (0.1 % as As,03, 0.00125% gamma isomer, 0.00125% and 0.00125% resp.) complete kill of lice (Damalinia ovis) was obtained in every case, and, in addition, at least three months protection against reinfection was obtained.Against keds (Melophagus ovinus) all except arsenic were efficient. Jetting with diazinon (0.0025%) and dusting with dieldrin 3% were also completely effective against both parasites.
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