Inundative Release of Archytas marmoratus (Diptera: Tachinidae) Against the Corn Earworm and Fall Armyworm (Lepidoptera: Noctuidae) in Whorl-Stage Corn

Abstract

A 3-yr pilot test was conducted to determine the feasibility of controlling early-season populations of corn earworm, Helicoverpa zea (Boddie), and fall armyworm, Spodoptera frugiperda (J. E. Smith), by augmentative releases of the tachinid parasitoid Archytas marmoratus (Townsend). Percentage parasitism of corn earworm larvae was increased to 42% in non-isolated fields of whorl-stage corn and >90% in isolated fields by inundative releases (≈1500 A. marmoratus ♀♀ per ha per week). Fall armyworm larvae were parasitized at a much lower level than corn earworm larvae. In a contiguous corn growing area, there was a positive correlation between density of corn earworm larvae and percentage parasitism within 0.8 km of the release field. The field with the greatest larval density and percentage parasitism of corn earworm larvae was the one farthest from the release site, indicating good host finding capability by A. marmoratus. These results show that inundative releases of this parasitoid could become an important component of integrated management strategies against early-season populations of corn earworm and fall armyworm. The high percentage of superparasitism in corn earworm larvae suggests that the release rate of A. marmoratus will need to be adjusted to host larval density.