SURVIVAL AND GROWTH OF BOLLWORM AND TOBACCO BUDWORM ON NONTRANSGENIC AND TRANSGENIC COTTON EXPRESSING A CRYIA INSECTICIDAL PROTEIN (LEPIDOPTERA, NOCTUIDAE)

Larval and pupal survival and development were assessed for bollworm, Helicoverpa sea (Boddie), and tobacco budworm, Heliothis virescens (F. ), fed. the transgenic variety (BTK) of cotton, Cossypium hirsutum L., that expressed an insecticidal protein, CryIA(c) from Bacillus thurin giensis Berliner subsp. kurstaki. The parameters measured for bollworm and tobacco budworm fed Bower buds excised from BTK or nontransgenic (non-BTK) cotton plants were percentage of survival, length of immatur e stage, length of pupal stage, larval/ pupal weights, and sex ratio o f each instar. Bollworm and tobacco budworm provided with BTK flower b uds as 1st, 2nd, 3rd, and 4th instars, fed Little and died after a per iod of approximate to 1-4 d. Importantly, a large percentage of 5th in stars of both species survived, pupated, and became adults on the BTK flower buds. Significantly more bollworm 5th instars pupated and survi ved to the adult stage when fed non-BTK cotton (76.0 and 51.3%, respec tively) compared with those fed BTK cotton (46.0 and 27.1%, respective ly). However, the number of tobacco budworm 5th instars that pupated a nd emerged as moths when fed non-BTK flower buds (73.3 and 41.3%, resp ectively) was not different from those fed BTK Bower buds (75.3 and 48 .0%, respectively). Larval weight was significantly lower for bollworm but not for tobacco budworm fed BTK flower buds as 5th instars. Total length of bollworm and tobacco budworm larval life was greater for th e larvae fed non-BTK flower buds compared with tile larvae fed BTK Bow er buds during the 1st-4th instars. Pupal weight, length of pupal stag e, and the percentage of male and female pupae produced were not signi ficantly different between the 2 plant phenotypes for the 2 insect spe cies. These results suggest that these transformed BTK cotton plants a re highly toxic to 1st-4th instars of bollworm and tobacco budworm, bu t not to 5th instars. movement of 5th instars of either insect species from non-BTK plants to BTK cotton plants in mixed stands could result in feeding and injury to BTK plants.