Behavioral response of lepidopteran pests on cotton expressing insecticidal proteins of Bacillus thuringiensis

摘要

Laboratory studies were conducted to evaluate the behavioral response of bollworm and fall armyworm on non-Bt cotton cultivars versus those expressing one (Bollgard~(TM)) or two (Bollgard II~(TM)) insecticidal proteins of Bacillus thuringiensis. Plastic trays consisting of cells with interconnecting corridors were used to assay larval movement and preference for meridic diet containing freeze-dried leaf tissue. After six hours, there was no significant difference in the variety bollworm or fall armyworm larvae preferred. For all varieties, 75-84 percent specimens were still in cells containing diet with incorporated leaf tissue. However, only 28 percent of bollworm larvae had moved from their original cell containing non-Bt tissue, compared to 49percent that had vacated cells containing either Bt cotton tissue. About 60 percent of fall armyworm larvae were found in cells containing non-Bt and dual-toxin tissue, and fewer were found on single-toxin tissue (43 percent). After 24 hours, 88 percentof bollworms were found in cells containing non-Bt plant tissue, compared to 68 percent and 53 percent of bollworms found in cells containing single-toxin and dual-toxin plant tissue, respectively. Fall armyworms were found in cells containing tissue from non-Bt and single-toxin cotton 61 percent and 71 percent of the time, respectively. Only 36 percent of fall armyworms were found in cells containing both Cry1Ac and Cry2ab toxins. Larvae of both bollworm and fall army worm were more inclined to move when placed in cells containing dual-toxin Bt plant tissue, as 78 percent of the larvae moved at least one cell after 24 hours. Approximately 50 percent of larvae moved when placed in cells containing non-Bt and single-toxin plant tissue.