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Frankfurt a, United Kingdom

The parasitoid complex of the sawfly gallers of the Pontania dolichura-group (Hymenoptera: Tenthredinidae: Nematinae) was studied. Since 1982 the author has collected and reared 10,382 galls of this species-group from 11 willow species in 36 natural sites of 6 European countries. As a result, the community of natural enemies of the Pontania dolichura-group comprises of four inquiline species (Coleoptera: Curculionidae: 2 spp, Lepidoptera: Geometridae: 1 sp, and Hymenoptera: Eurytomidae: 1 sp) and 22 parasitoid species (Hymenoptera: Braconidae: 7 spp, Ichneumonidae: 6 spp, Chalcidoidea: 9 spp). Some notes are given on host species, distribution, and biology of all recorded species of the enemy complex. Mortality caused by parasitoids including inquilines varied significantly between gallers and sites, ranging from 0.77 % in Pontania virilis Zirngiebl 1955 to 96.7 % in Pontania nigricantis Kopelke 1986. No enemy-free samples were found, the maximum number of natural enemies per host galler per site ranged up to 10 species in Pontania nigricantis The parasitoid complex of the Pontania dolichura-group is dominated by ectoparasitic idiobionts (14 spp) rather than by endoparasitic koinobionts (8 spp). 17 enemy species were infrequent in the samples occurring at most in 4 samples and/or sites. The predominant parasitoids were Pteromalus dolichurus (Thomson 1878) and Scambus vesicarius (Ratzeburg 1844), occurring in 43 and/or 39 samples and causing a maximum host larvae mortality of 46.2 % and 39.8 %, respectively. A plant-based mortality was generally not found in the species of the Pontania dolichura-group. Most of the species examined are able to induce galls without oviposition. An average of 1.47 % (in Pontania virilis) up to 25.6 % (in Pontania dolichura Thomson 1871) of the reared galls had no egg. © 2010 E. Schweizerbart'sche Verlagsbuchhandlung, D-70176 Stuttgart. Source

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