Effects of transgenic cotton on mortality and development of pink bollworm(Lepidoptera : Gelechiidae) larvae

Pink bollworm (PBW), Pectinophora gossypiella (Saunders), larval mortality after different times of confinement on NuCOTN 33B(R) (Bt) cotton bolls was compared with larval mortality on Delta and Pineland 5415 cotton bolls as controls. We also compared larval mortality on different age cotton fruitin g forms and determined the Bt susceptibility of different age PBW larvae. I nfesting Bt bolls with PBW eggs that hatched within 24-h resulted in 92% la rval mortality after 48-h and 100% mortality after 4 days or longer. There were no differences between cultivars in numbers of larval entrances holes into bolls. Larval mortality percentages decreased when older (second- and third-instar) larvae were placed on bolls compared with first-instar larvae . Generally, days to pupation for both males and females were longer on Bt bolls compared with non-Bt cotton. Ninety-three to 100% of the progeny from moth pairs from second- and third-instar larvae that survived on Bt bulls died when transferred to Bt bolls. There were no significant mortality diff erences for larvae feeding on Bt fruiting forms of different ages ranging f rom one-half grown flower buds to 40-day-old immature green bolls.