Factors associated with mortality of the overwintering generation ofSesamia nonagrioides under field conditions

Factors affecting overwintering mortality in the Mediterranean corn stalk borer,Sesamia nonagrioides Lefebvre (Lepidoptera: Noctuidae), were investigated under field conditions in the southeast Mediterranean region of Turkey. During two consecutive years larvae and pupae were sampled from December to April in maize plots sown on three different dates. Field-collected larvae and pupae were reared and the emerged parasitoids were recorded. An effect of sowing date on total numbers ofS. nonagrioides was found with reduced populations in the early sown plots. Larval parasitism did not significantly affect overwintering mortality.Habrobracon hebetor (Say) (Hymenoptera: Braconidae) caused 11% parasitism and was found only in the first year of the study. Pupal parasitoids were predominantlyIchneumon sarcitorius caucasicus Meyer,Barichneumon sp. andPimpla spuria Gravenhorst (Hymenoptera: Ichneumonidae) and the parasitism level was 11% in both years of the study.