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United States Department of Agriculture

Agricultural Research Service

Title: Host-Parasitoid Hormonal Signaling and Parasitism by Cotesia Congregata in the Tobacco Hornworm Manduca Sexta

item Beckage, Nancy - UNIV. OF CALIFORNIA RIVER
item Gelman, Dale

Submitted to: Proceedings, XXI International Congress of Entomology
Publication Type: Abstract Only
Publication Acceptance Date: August 1, 2004
Publication Date: August 15, 2004
Citation: Beckage, N.E., Gelman, D.B. Host-parasitoid hormonal signaling and parasitism by cotesia congregata in the tobacco hornworm manduca sexta. Proceedings, XXI International Congress of Entomology. August 15-21, 2004.

Technical Abstract: Hormones play a critical role in the growth and development of insect parasitoids. Host juvenile hormone and ecdysteroid levels are disrupted during parasitism of the tobacco hornworm by the gregarious braconid wasp Cotesia congregata. Following parasitization of host larvae in the fourth instar, the wasps emerge from developmentally arrested fifth instar larvae which have ceased feeding. Both juvenile hormone (JH) and ecdysteroids are produced by the parasitoids and secreted into the hemolymph of the host. In the host's last instar, the ecdysteroid titer of the host peaks at a level four-fold higher than the peak concentration found in prewandering unparasitized larvae, and in contrast to nonparasitized control larvae the parasitized larvae fail to expose the dorsal vessel or exhibit wandering behavior. The application of methoprene to parasitized larvae suppresses the emergence of parasitoids from the host, and also appears to interfere with the release of ecdysis-triggering hormone in the parasitoid. Results in this system will be compared to recent findings in other host-parasitoid associations.

Last Modified: 4/22/2015
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