Transgenic resistance to the Colorado potato beetle in Bt-expressing eggplant fields

Colorado potato beetle (CPB; Leptinotarsa decemlineata-Say) is a serious pe st because it has developed resistance against insecticides. Three transgen ic eggplant (Solanum melongena L,) lines bearing a mutagenized Bacillus thu ringiensis; Berl, gene coding for the Cry3B toxin, and the nontransformed c ontrol DR2-line were tested in field trials to assess their insect resistan ce. The transgenic lines 3-2, 6-1, and 9-8 were tested at two different loc ations in a randomized complete-block design. Samples were taken biweekly t o assess the level of CPB and the presence of other insects. At harvest, to tal yield and fruit number per plot were recorded. Two transgenic lines sho wed high levels of resistance at both locations, as measured by CPB abundan ce and yield, Fruit production was almost twice as great in the highly resi stant lines (3-2 and 9-8) as in the nontransformed control. The 6-1 transge nic line showed an intermediate Level of resistance: it was similar to the control under heavy CPB pressure and was comparable to the other transgenic lines under milder infestations. Analysis by double antibody sandwich-enzy me linked immunosorbent assay (DAS-ELISA), performed on different tissues, revealed a fewer amount of Cry3B protein in the 6-1 transgenic line than in lines 3-2 and 9-8, No detrimental effects on nontarget arthropods (includi ng the chrysomelid Altica) were evident. Field observations confirmed that Bt may be able to control CPB infestation in eggplant, representing a poten tial effective and environmentally safe means of pest control.