Pheromone Concentration as a Mechanism for Reproductive Isolation between Two Lepidopterous Species.

Pheromone-releasing females of the closely related noctuid moths Trichoplusia ni and Autographa californica attract mainly males of their own species. Sex-pheromone-concentration specificity appears to be an important reproductive isolating mechanism for these two species. Apparently, both species utilize the same pheromone, cis-7-dodecenyl acetate, for mating communication, but T. ni utilizes a higher level than does A. californica. Traps releasing amounts of cis-7-dodecenyl acetate that are highly attractive for males of one of the species catch very few males of the other species.