Susceptibility of Field Populations of Pink Bollworm (Lepidoptera: Gelechiidae) to Azinphosmethyl and Permethrin and Synergism of Permethrin

Abstract

Responses of five field-collected populations of the pink bollworm, Pectinophora gossypiella (Saunders), from Arizona and southern California, were compared with those of a standard, susceptible-laboratory strain. Field strains showed less than 2-fold difference in response to azinphosmethyl at LD50 but had variable levels (1.3- to 18.3-fold) of response to permethrin. Strains from Yuma and Phoenix (Arizona) and Westmoreland (California) had highest levels of resistance to permethrin. Application of permethrin with an oxidase inhibitor (piperonyl butoxide [PBO]) and an esterase inhibitor ( S,S,S -tributyl phosphorotrithioate [DEF]), produced less than 2-fold synergism in the Yuma strain. Results suggest that non metabolic factor(s) may be involved in permethrin resistance of the Yuma field strain because neither PBO nor PBO plus DEF suppressed resistance completely. Permethrin resistance in pink bollworm may be partially conferred by a kdr gene.