Target-site insensitivity as the mechanism of resistance to organophosphorus, carbamate, and cyclodiene insecticides in tobacco budworm adults
1995
Kanga, L.H.B. | Plapp, F.W. Jr
Mechanisms of resistance to organophosphorus, carbamate, and cyclodiene insecticides were investigated in adult tobacco budworms, Heliothis virescens (F.). Comparative studies on profenofos toxicity with or without synergists failed to demonstrate that enhanced metabolism was a major mechanism of resistance to this insecticide. Percentage of survival of several partially resistant tobacco budworm populations at diagnostic concentrations of profenofos and methomyl was highly correlated, suggesting the same mechanism confers resistance to these insecticides. Differences between resistant and susceptible tobacco budworms in inhibition of acetylcholinesterase by tetrachlorvinfos (7-fold), methomyl (7.6-fold), and carbaryl (4-fold) indicated that target-site insensitivity was a major mechanism of resistance to organophosphorus and carbamate insecticides. The high correlation of survival of field tobacco budworm populations exposed to diagnostic concentrations of endosulfan and dieldrin suggested that the same mechanism (target-site) conferred resistance to both insecticides. Measurements of penetration of radiolabeled profenofos indicated that a decrease in insecticide uptake may be an additional resistance factor in the tobacco budworm. Because target-site resistance to insecticides is expressed in both larvae and adults, monitoring for resistance in adults is appropriate with these insecticides.
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