Response of the Tobacco Budworm to Permethrin and Methyl Parathion in Arizona, 1977-1990
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AbstractField populations of tobacco budworm. Heliothis virescens (F.). have been monitored annually since 1977 with topical applications of synthetic pyrethroid insecticides (primarily permethrin) and methyl parathion to detect changes in insecticide susceptibility. These data showed that LD₅₀'s fluctuated somewhat from year to year with permethrin. but with one possible exception. the fluctuations were not sufficient to change levels of expected control in the field. Field populations continue to show susceptibility to permethrin even though one Maricopa County population showed an increase in the LD₅₀ to 12.4 in 1988. Field populations continue to show resistance to methyl parathion and susceptibility to permethrin.