A Technique for Distinguishing Virgin and Mated Males of Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae)

Studies on the mating history of male Lepidoptera are generally lacking because of difficulties in determining male mating status. In previous studies, presence/absence of pigmented fluids inside the male primary simplex have been used successfully for determining mating status. However, males of European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), have creamy white fluids in the primary simplex instead of pigmented fluids, so presence/absence of pigmented fluids inside the primary simplex cannot be used to assess mating status in this species. We developed a scoring system for the fluids inside the primary simplex that allowed us to classify O. nubilalis male mating status and the timing of copulation. The scoring system relies on differences in the fluids in the 1^st, 2^nd and 7^th segments of the primary simplex. Males known to be virgins, mated <1d previously and mated >1d previously could be distinguished with a 6.3% error rate. The method was verified on 41 males in a blind study, with 100% accurate classification of the males.