Survival of Archytas marmoratus (Diptera: Tachinidae) from superparasitized corn earworm larvae (Lepidoptera: Noctuidae)
2000
Carpenter, J.E. | Proshold, F.I.
We investigated the survival of Archytas marmoratus (Townsend) from superparasitized Helicoverpa zea (Boddie) larvae. About half of the planidia of A. marmoratus brushed on larvae of the corn earworm, H. zea, became established. Fourth instars were more susceptible to parasitization than other instars, but parasitoid eclosion from superparasitized hosts was greatest in fifth instars. The number of hosts producing A. marmoratus adults declined linearly with the number of maggots per host, with no eclosion of A. marmoratus from hosts with >10 maggots. When third-instar corn earworm were collected from artificially infested, whorl-stage corn after the release of A. marmoratus, 75% of the parasitized larvae were superparasitized. Superparasitism reduced parasitoid eclosion more severely in field plots than in the laboratory. As in laboratory studies, the number of hosts producing A. marmoratus adults declined linearly with an increased number of maggots, but no parasitoid eclosed if hosts had more than four maggots. The number of maggots per corn earworm larva was highly correlated with percentage parasitism. Consequently, the release rate of A. marmoratus might need to be adjusted to host density so that superparasitism does not reduce the survival rate of the parasitoid.
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