The swede midge (Contarinia nasturtii) was first identified in Ontario in 2000 as the causal agent of extensive damage to cole crops in several locations in eastern Canada. This fly has the potential to spread throughout cole crop production areas causing significant yield losses. Damage symptoms on plants include absent or deformed heads, twisting of plant tissue and bacterial rots from secondary infections, all of which render the crop unmarketable. Efficacy of pyrethroid (deltamethrin and permethrin) and organophosphate (acephate) insecticides in controlling damage by swede midge to broccoli and cabbage was evaluated in field trials at two farms in Ontario in 2001. Differences in host resistance were assessed at the same locations using eight broccoli, one cabbage and three cauliflower varieties, chosen on the basis of apparent differences in susceptibility observed by Ontario growers. Further studies will evaluate resistance in relation to chemical and physical characteristics of host plants. Population dynamics were monitored with sticky traps on a semiweekly basis. Twice a week plants were observed for damage symptoms and rated for relative susceptibility to the swede midge. The implications of our findings for swede midge control will be discussed.
Species 1: Diptera Cecidomyiidae Contarinia nasturtii (swede midge)
Species 2: Capparales Brassicaceae Brassica oleracea (broccoli, cabbage)
Keywords: Insecticide efficacy, Host resistance
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA