Effectiveness of transgenic eggplant (Solanum melongena L.) against the Colorado potato beetle

Transgenic 'Harris Special' eggplant genotypes containing a modified cryIIIA gene of Bacillus thuringiensis tenebrionis CryIIIA δ-endotoxin were evaluated in the field for resistance to the Colorado potato beetle, Leptinotarsa decemlineata (Say). Selfed progenies of six transgenic primary transformants were evaluated against susceptible plants and susceptible plants treated with imidacloprid using a randomized complete block design. The buildup of Colorado potato beetle populations in the study field was encouraged through the use of potato nurse plots and direct seeding of the field with adult beetles. For six weeks during June and July, the density of eggmasses, larvae, and adults present was determined. To confirm the results seen in the field, a laboratory feeding study using field collected leaves was conducted. In this study, the use of transgenic eggplant significantly reduced field populations of Colorado potato beetle when compared to non-transgenic plants. Overall, each transgenic line suppressed all life stages of the Colorado potato beetle populations in the field at levels not significantly different from the insecticide check. The results seen in the field were confirmed by the feeding study. In the laboratory, feeding by Colorado potato beetle adults was significantly reduced by all transgenic lines when compared to the non-transgenic plants. Only one of the six progenies tested decreased feeding at a level higher than the insecticide treated plants. Development of these transgenic strains into a commercially acceptable eggplant variety should provide an alternative to the use of chemical insecticides against Colorado potato beetle.