Die Parasitenkomplexe europäischer Diprionidae in ökologisch-evolutionsbiologischer Sicht

Abstract

Parasite community of European Diprionidae from an ecological-evolutionary point of view Neodiprion sertifer, the only Eurasian species of this nearctic genus, is systematically and, due to its hibernation in the egg stage and its aestivation in the cocoon-stage, also biologically an outsider in the European Diprionid-fauna (Fig. 1). It is assumed that the ancestors of N. sertifer immigrated from western North America via Beringia to Eurasia during the Pleistocene period In spite of its exceptional status, this sawfly species has a rich parasitoid complex, characterized by several highly specific larval parasites, which, in size und diversity, is equivalent to the parasite-spectra of autochthonous European Diprionids such as Diprion pini, Microdiprion pallipes, etc. (Tab. 1 and 2). Based on a comparative analysis of these parasite complexes, a trial is made to explain 1. from which hosts the parasites of N. sertifer have originated and 2. which biological adaptations have allowed them to colonize the new host niche and to synchronize with the strictly univoltine life-cycle of N. sertifer. The boreo-montane Murodiprion pallipes has apparently played a key role as a source for parasitoid species of N. sertifer. Adaptation to the new host has been achieved by the acquisition of an obligatory summer diapause in such highly specific larval parasites as Exenterus abruptorius, Lamachus eques, Lophyroplectus luteator (Fig. 5) and in the «sertifer-form» of the egg parasite Dipriocampe diprioni (Fig. 3), whereas in Chrysonotomyia spp. the ability to develop as facultative hyperparasites has enabled them to bridge the summer gap when fresh host eggs are not available (Fig. 3 und 4).