Effect of temperature on toxicity of three pyrethroids to horn flies |
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Authors: | NANCY C. HINKLE ,D. CRAIG SHEPPARD,KAINE BONDARI &dagger ,JERRY F. BUTLER |
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Affiliation: | Department of Entomology, University of Georgia, Tifton 31793. |
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Abstract: | Predictive models describing best-fit regression equations for per cent mortality of horn flies as a function of temperature were determined for each of three pyrethroid insecticides (fenvalerate, flucythrinate and permethrin) over the temperature range 20-35 degrees C. Susceptible horn flies, Haematobia irritans (L.), were exposed to c. an LC70 dose of each pyrethroid using a residue-on-glass method. This technique used confined exposure in chambers with temperatures of 20, 25, 30 and 35 degrees C. Within this range, mortality was greatest at 25 degrees C with all three insecticides. Estimated temperature-mortality equations for each pyrethroid revealed different responses of horn flies to each of these insecticides. Horn flies exposed to flucythrinate demonstrated a linear mortality response that varied inversely with temperature. The response to permethrin was described by a quadratic equation, while the response to fenvalerate was best fitted by a cubic equation. |
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Keywords: | Haematobia irritans fenvalerate flucythrinate permethrin temperature resistance horn flies pyrethroids |
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