Submitted to: Journal of Entomological Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 4, 1999
Publication Date: N/A
Interpretive Summary: The fall armyworm and corn earworm are the two most destructive insect pests of corn in the southeastern United States. Augmentative releases of a native parasitoid, Archytas marmoratus, in conjunction with other management strategies may reduce the usage of environmentally harmful pesticides for the control of these two pests. The results of this study provide a better understanding of overwintering and seasonal abundance of the parasitoid. The findings will benefit those interested in utilizing the parasitoid as a biocontrol agent in integrated management of corn insects as well as other crops.
Archytas marmoratus (Townsend) was reared on corn earworm, Helicoverpa zea (Boddie) or fall armyworm, Spodoptera frugiperda (J. E. Smith). Rearing chambers were programmed for a constant temperature of 15, 16, 19, 20, 22, 24, or 25#C and a photoperiod of 10:14 (L:D) or 25#C and a photoperiod of 12:12 (L:D). Development of parasitoids was faster when corn earworm larvae were parasitized than when fall armyworm larvae were parasitized. At 15#C parasitoid survival was poor on both hosts but at 16#C, more parasitoids eclosed on corn earworm than fall armyworm. Diapause induction in this strain of corn earworm was low. All pupae that eclosed after being in diapause produced an adult corn earworm. The data suggested that A. marmoratus is not influenced by diapause induction in its host but continues to develop above the threshold temperature for survival. This would restrict its overwintering as a larva or pupa to regions that have a continuous, nondiapausing host population. Thus, yearly establishment of A. marmoratus in more temperate areas would be required.