Growth and survival of Heliothis virescens (Lepidoptera:Noctuidae) on transgenic cotton containing a truncated form of the delta endotoxin gene from Bacillus thuringiensis

Lines of transgenic cotton, Gossypium hirsutum L., that contain a truncated version of the delta endotoxin gene from the bacterium Bacillus thuringiensis var. kurstaki were tested in the laboratory for effects on growth and survival of tobacco budworm, Heliothis virescens (F.). Five transgenic lines contained the cryIA (b) gene from bacterial strain HD-l and one cotton line (MON-249) had the cryIA (c) gene from the strain HD-73. Neonate larvae of tobacco budworm were grown for 6 d on 10 different kinds of plant structures of the six transgenic, field-grown cotton lines and the nontransgenic, parental ‘Coker 312’. Mean growth and survival of neonate larvae to 6 d for the transgenic lines as a group were significantly less than ‘Coker 312’ for every plant structure. Among the six transgenic lines, significant variation in survival of neonate larvae to 6 d on terminal leaves, small squares, and on bracts were observed; however, insect weights were very low and not different among transgenic lines. When larvae were fed on artificial diet before they were placed on mature leaves they tended to have higher survival on one transgenic line (MON-62) than on the others. No larvae pupated on transgenic lines. These laboratory assays using field-grown plant struchues indicate that cotton transgenic for delta endotoxin has great potential in controlling tobacco budwonll larvae under field conditions.