Ratios (1:0, 9:1, 3:1, 1:1, 1:3, 1:9, and 0:1) of Z,Z- to Z,E- isomers of 7,11- hexadecadienyl acetate (7,11-16:Ac) were tested as trap baits for capture of male pink bollworm moths, Pectinophora gossypiella (Saunders), in fields treated with either Z,Z-7,11-16:Ac or gossyplure (1:1 ratio of Z,Z- to Z,E-7,11-16:Ac, the sex pheromone of the pink bollworm), or left untreated. Males were captured ... [Show full abstract] primarily in traps baited with gossyplure in gossyplure-treated fields (78%of total catch) and in untreated fields (66%of total catch). However, in fields treated with Z,Z-7,11-16:Ac, 69% of the males were captured in traps containing the 9:1 ratio and 3% in traps baited with gossyplure, an induced shift in the response of males. The observed shift in male response suggests the possibility of male annihilation using traps of insecticide-treated sources (9:1 ratio, for example) in fields treated with Z,Z-7,11-16:Ac. Unlike males in fields treated with gossyplure, males in fields treated with Z,Z-7,11-16:Ac are not responsive to sources emitting gossyplure. The induced shift in male response to isomer ratios is attributed to selective adaptation of Z,Z- receptor sites on the antennae of males leading to the perception of the 9:1 ratio as ca. 1:1.