Control of Contarinia nasturtii Keiffer (Diptera: Cecidomyiidea) by foliar sprays of acetamiprid on cauliflower transplants

Swede midge (Contarinia nasturtii Keiffer) is a serious gall-forming insect pest of cruciferous plants in Europe and southwestern Asia. In North America, it was first identified in Ontario, Canada, in 2000 and in Niagara County, New York, US, in 2004. The insect is now rapidly spreading in Canada and the US. To date, infestation of C. nasturtii has been confirmed in 46 counties in Canada. The US Department of Agriculture has confirmed the presence of C. nasturtii in 6 counties in the US, although our surveys using pheromone traps have identified 19 counties in New York and one county in Massachusetts and New Jersey. Currently, hundreds of farms in the northeastern US that grow cruciferous vegetables are at risk for infestation of C. nasturtii through movement of vegetable seedlings and harvested produce from infested areas. To prevent the spread of C. nasturtii, the efficacy of acetamiprid, the first labeled insecticide in the US for C. nasturtii control, was evaluated by using foliar sprays on cauliflower seedlings. Results indicated the efficacy of acetamiprid on C. nasturtii was 99.52% 100% and 99.83% when cauliflower seedlings were sprayed before inoculation with C. nasturtii, 0 and 4 d after inoculation, respectively. The efficacy of acetamiprid was reduced to 69.89% when seedlings were sprayed 8 d after inoculation, and C. nasturtii larvae could successfully pupate and emerge after the spray. These results indicate that acetamiprid can effectively control C. nasturtii on cauliflower seedlings, especially in the early stage of insect occurrence. Based on these results, we suggest that seedlings be treated with acetamiprid as a foliar spray before shipment of seedlings from C. nasturtii infested areas.