Parasitoids of Delia radicum (Diptera: Anthomyiidae) in canola : assessment of potential agents for classical biological control

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Hemachandra, Kennantudawage Siril
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Delia radicum L. is an important insect in canola on the Canadian Prairies and there is no single effective method of control. Hence, classical biological control has been proposed. The main objective of this study was to assess the parasitoid community of D. radicum in canola on the Canadian Prairies and Europe. Immature stages of D. radicum were sampled in six canola fields on the Canadian Prairie Provinces and in 11 canola fields and one brassica vegetable field in Switzerland and Germany. Immatures were individually reared in the laboratory until emergence of parasitoids and adult D. radicum. Parasitoid species found in canola on the Canadian Prairies and in canola and brassica vegetables in Europe included Trybliographa rapae (Westwood) (Hymenoptera: Eucoilidae) and Aleochara bilineata Gyllenhal (Coleoptera: Staphylinidae). Aleochara verna Say (Coleoptera: Staphylinidae) was found only in Canadian canola while A. bipustulata L. (Coleoptera: Staphylinidae) was found only in European canola and brassica vegetables. Minor parasitoids found in canola included Phygadeuon trichops (Thomson) (Hymenoptera: Ichneumonidae), three undescribed Phygadeuon species, Aphaereta minuta (Nees) (Hymenoptera: Braconidae), Aleochara brevipennis Gravenhorst (Coleoptera: Staphylinidae) and Trichopria sp. (Hymenoptera: Proctotrupidae). Specimens collected by other workers in North America and labeled as A. bipustulata were examined and found to be A. verna...