Biology and Rearing of Diapetimorpha introita (Cresson) (Hymenoptera: Ichneumonidae) on Host and Non-host Noctuid Pupae

Laboratory studies were conducted to identify factors that influence Diapetimorpha introita (Cresson) reproduction and development rate on Spodoptera spp., Helicoverpa zea (Boddie), and Heliothis virescens (F.), Laboratory colonies of D. introita were successfully maintained on S. frugiperda (J. E. Smith) pupae placed in multicellular rearing units. Mated D. introita females produced an average of 81.3 eggs per individual over a mean lifespan of 23.6 days. Sex ratios were skewed with 40% more males than females produced from mated females. Unmated females produced all male progeny. Diapetimorpha introita females tended to select 3 to 5-day-old S. frugiperda pupae over younger or older pupae. Diapetimorpha introita successfully developed to the adult stage on host Spodoptera spp. and non-host H. zea and H. virescens pupae. Duration of larval stages was dependent upon host and temperature. Duration of pupal stages not exposed to diapause-inducing temperatures were dependent upon host, and adult weights were dependent upon host species, host weight, and temperature. Temperatures of 18 or 22°C resulted in ≥ 90% diapause regardless of host species. Generally, parasitoids from large host pupae developed more slowly and weighed more than those developing on smaller hosts. Successful utilization of D. introita as a candidate for augmentative releases against overwintering populations of Spodoptera spp. depends upon the advancement of in vivo mass rearing techniques.