Insect Populations on Bacillus thuringiensis Transgenic Sweet Corn

Abstract

Insect populations and damage in three plantings (early, mid-, and late-season) of Bacillus thuringiensis (Bt) transgenic sweet corn were compared to a non-transgenic isoline at Charleston, SC, during 2000. The transgenic corn was expressing the crylA(b) gene from B. thuringiensis var. kurstaki. No fall armyworms, Spodoptera frugiperda (J. E. Smith), were present in the early-planted crop, and numbers of corn earworms, Heliocoverpa zea (Boddie), were significantly reduced in the Bt-transgenic corn compared to the non-Bt isoline. The non-Bt isoline had 65% H. zea infested ears compared to only 10% ears from the Bt-transgenic line. Damage and numbers of H. zea and S. frugiperda also were significantly higher in the non-Bt sweet corn planted in mid- and late-season plantings. Percent damaged ears by H. zea was 77% in the non-transgenic sweet corn and 21% in the Bt-sweet corn during the mid-season crop. In the late-planted crop, populations of H. zea averaged 15 per 120 ears in the non-BT isoline compared to less than 2 per 120 ears in the Bt-transgenic crop. Whorl damage by fall armyworms significantly reduced plant height in both mid-season and late-season non-transgenic crops but not in Bt-transgenic sweet corn. Numbers of other insects and spiders were low and not significantly different between the two treatments. Bt transformed sweet corn will play a major role in reducing populations of H. zea, S. frugiperda and limiting pesticides in this crop.