Wechselseitige Beeinflussung des Entwicklungsablaufs bei entomophagen Parasiten und deren Wirten, erörtert am Beispiel vonColeophora-Arten(Lep., Coleophoridae) undUrophora-Arten(Dipt., Trypetidae)

Abstract

This study compares the host-parasite relation betweenColeophora ? alcyonipennella andAgathis sp., on the one hand, andUrophora spp. andEurytoma tibialis, on the other hand.Coleophora-Agathis is a striking example for a host-parasite relation where the larval development of the parasitoid is controlled by the endocrine system of the host, which results in an optimal synchronization between the life-cycles of the moth and its specialized Braconid parasite. Attempts to obtain adultAgathis during the winter season for the biological control ofColeophora in New Zealand have met with considerable difficulties because of the hormonal dependence of the parasite on the host. The rearing and the transfer of adult parasites was not possible until the diapause of the host could be ended experimentally. In the complexUrophora-E. tibialis the parasite larvae interferes with the hormonal system controlling the development of the host. In hibernating generations ofUrophora spp. the parasite induces a premature onset of the process of pupation of the host, but consumes the latter when it has formed its puparium. In both hosts the hormonal reactivation of the diapausing full-grown larva results in a change of the position of the larva in its case or gall, before the morphogenetic changes involved in pupation take place. The larvae ofAgathis as well asE. tibialis do not kill their hosts until the latter have reversed their position within the case or gall. In this way the emergence ofAgathis from the case ofColeophora and the emergence ofE. tibialis from the gall ofUrophora is facilitated.