production of the specific pheromone blend in females is controlled by a single autosomal factor. heterozygous females produce more "e" isomer than "z". the response to these pheromones in the olfactory cells of male european corn borers is also controlled by a single autosomal factor with two alleles. analysis of the electrophysiological signaling of olfactory cells showed that those with two "e" alleles responded strongly to the "e" isomer and weakly to the "z" isomer. the opposite effect was found in homozygous "z" males. males heterozygous for this autosomal factor exhibited similar neurological responses to both isomers of pheromone. finally, response to the pheromone is controlled by two factors, a sex-linked gene on the z chromosome and another on an autosome. in species of lepidoptea, sex is determined through the zw sex-determination system where males are homozygous zz and females are heterozygous zw.