Junce Tian, Mao Chen, A. Shelton
Arthropod Management Tests
Swede midge (SM), Contarinia nasturtii (Kieffer) (Diptera: Cecidomyiidae), is a pest of cruciferous (Brassicaceae) plants which include canola, cabbage, broccoli, cauliflower and Brussels sprouts. It is widely distributed in Europe and southwestern Asia and was first discovered in North America in Canada in 2000. By the end of 2010, SM had been found in a total of 26 counties in New York and one county each in Massachusetts, New Jersey, Connecticut, Vermont and Ohio. It is rapidly spreading throughout Canada and threatens the large area grown to canola. Traditional insecticidal control has proven unreliable under high populations, and may not be economically suitable for large-scale field crops like canola, so this trial was conducted to determine if three dipteran-active proteins from Bacillus thuringiensis would be effective against SM. If they proved effective, this would open up the possibility of genetically engineering cruciferous plants to express these proteins. Cry4Ba and Cry11Ba were obtained from M. Adang (Univeristy of Georgia) and Cry2Ab from Monsanto. A treatment of Warrior II, λ-cyhalothrin, was used as a positive control. The SM colony used was obtained from Switzerland (R. Baur) in 2004 and was subsequently reared in our laboratory in a chamber at 22 °C, RH 75-78 % and 16h L: 8h D. Cauliflower plants with 4-5 true leaves were used in the bioassay. The apical meristems of plants were dipped into one of seven solutions (500 ppm Cry2Ab, 1000 ppm Cry4Ba, 2000 ppm Cry4Ba, 1000 ppm Cry11Ba, 2000 ppm Cry11Ba, 200 ppm λcyhalothrin and distilled H2O) and transferred into 30-ml plastic cups. Five 9-d old C. nasturtii larvae were placed on each tip and we used 5 replications for each treatment. Survival was determined after 72h. Data were transformed into arcsine square-root and analyzed by one-way analysis of variance (ANOVA) and Tukey’s multiple-range test.