European Corn Borer: Lack of Synchrony of Attraction to Sex Pheromone and Capture in Light Traps123

Abstract

During the 1971–72 spring and summer flights of Ostrinia nubilalis (Hubner), attractiveness of the synthetic sex pheromone Z-11-tetradecenyl acetate (Z-11-tda) was compared with light trap captures of male and female European corn borers and egg masses deposited in cornfields. Egg mass deposition maxima occur within 1–3 days of the Class 2 female (captured within 24 h after mating) maxima in the light trap. The male maxima in the light trap were synchronous with the female maxima (classes intercombined: Class 1—unmated, ovaries gravid; Class 2—spermatophore full, ovaries gravid; Class 3—spermatophore assumed partially depleted of sperm; and Class 4—spermatophore assumed depleted of sperm and ovaries assumed depleted of eggs. But when moderate to large populations of moths were present, the male maxima in the sex pheromone trap occurred after the female and male maxima in the light trap and after most egg masses had been deposited in cornfields. The results demonstrate that competition for males by feral females would reduce the efficacy of pheromone traps and also the importance of alternative monitoring systems for proper biological interpretation of European corn borer population data obtained from sex pheromone traps.