Host-induced ecdysteroids in the stop-and-go oogenesis in a synovigenic parasitoid wasp

Autor: J. P. Monge, Aurélie Bodin, Fabrice Vannier, Nathalie Mondy, Jean-Paul Delbecque, Nicole Mandon, Bruno Jaloux
Přispěvatelé: Laboratoire d'Ecologie des Hydrosystèmes Fluviaux (EHF), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Besse, Christine, Institut de recherche sur la biologie de l'insecte UMR7261 (IRBI), Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Martin Sempore, Brigitte, Université de Tours-Centre National de la Recherche Scientifique (CNRS)
Rok vydání: 2007
Předmět:
Zdroj: Archives of Insect Biochemistry and Physiology
Archives of Insect Biochemistry and Physiology, Wiley, 2007, 65, pp.103-111
Archives of Insect Biochemistry and Physiology, Wiley, 2007, pp.1036111
ISSN: 0739-4462
1520-6327
Popis: Eupelmus vuilleti (Hymenoptera; Eupelmidae) is a solitary ectoparasitoid producing yolk-rich eggs. The female oviposits mainly on the fourth larval instar of Callosobruchus maculatus (Coleoptera; Bruchidae), which develop within pods and seeds of Vigna unguiculata (Fabacae). Parasitoid females are synovigenic, i.e., they are born with immature eggs and need to feed from the host to sustain egg production during their entire lifetime. However, eggs are rapidly resorbed in unfavourable conditions and an efficient stop-and-go mechanism controls oogenesis in such animals. In this study, the possible involvement of ecdysteroids in the regulation of parasitoid oogenesis is examined. In a first step, the identity and titre of ecdysteroids in reproductively active and inactive female parasitoids were investigated by high performance liquid chromatography followed by enzyme immuno-assay (EIA/HPLC). A larger secretion of ecdysone was found in female during their reproductive period compared with inactive females. In a second step, both the secretion of ecdysteroids into the medium of in vitro incubated ovaries and the ecdysteroid content of females reared with or without host were measured (EIA). The presence of the host, which represents both the oviposition site and the nutritional source, induced an active biosynthesis of ecdysone. This synthesis started at a slow rate after host introduction and reached a maximum after 48 h. When hosts were available, this synthesis was cyclic and continuous during the entire female lifetime. These results showed that host presence triggered ovarian synthesis of ecdysteroids, which are involved in a stop-and-go regulation of egg production linked to host availability.
Databáze: OpenAIRE
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