Post-diapause development of Delia radicum (Diptera: Anthomyiidae) and host range of Aleochara bipustulata (Coleoptera: Staphylinidae) for classical biological control in Canadian canola

Aleochara bipustulata, a European natural enemy of Delia radicum, shows promise as a biological control agent in Canadian canola. Post-diapause development of D. radicum and Aleochara bilineata was studied in the laboratory. Prairie D. radicum developed more slowly than from Ontario, suggesting particular source populations of A. bipustulata may be better suited to western Canada than others. Aleochara bilineata develops too slowly for effective predation of early immature D. radicum. Aleochara bipustulata's host range was studied in the laboratory and its habitat associations studied in Europe. Beneficial Diptera species were either unsuitable hosts, or for Lonchaea corticis found in habitats not visited by A. bipustulata. Suitable laboratory host species were relatively small or closely related to D. radicum. Species with unusual puparia were less likely to be accepted as hosts than D. radicum. Species which develop quickly in the pupal stage, or with relatively heavy puparia, were unsuitable hosts.