Differential survival of male and female partially resistant horn flies (Diptera: Muscidae) on steers treated with permethrin.
Males and females from a heterozygous, resistant strain (SR) of the horn fly, Haematobia irritans (L.), were tested for survival until reproductive maturity on steers with ear tags in outdoor, screened enclosures and on steers sprayed on the neck in an indoor isolation room. After 6 d, female SR flies on outdoor steers with one tag had 10 times greater survival than males; almost no SR flies on steers with two ear tags survived. Survival of male and female SR flies on steers sprayed on the neck was reduced during the first 24 h, but not thereafter. Lower survival of males compared with females on treated steers reflected differential survival of the sexes during exposure to treated cloths in a laboratory bioassay. Hair samples from neck, back, rump, and lower legs of steers with ear tags in outdoor pens were tested for toxicity to the SR flies. These bioassays indicated high localization of insecticide on the neck of steers with ear tags.
McDonald
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PT
U.S. Livestock Insects Laboratory, USDA-ARS, Kerrville, Texas 78029.
Schmidt
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CD
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy*; D004478:Ectoparasitic Infestations / Q000188:drug therapy / Q000662:veterinary*; D005260:Female; D007305:Insecticide Resistance; D007306:Insecticides / Q000627:therapeutic use*; D008297:Male; D009117:Muscidae; D026023:Permethrin; D011722:Pyrethrins / Q000627:therapeutic use*
D007306:Insecticides; D011722:Pyrethrins; D026023:Permethrin