Evaluation of transgenic corn for resistance to corn earworm (Lepidoptera : Noctuidae), fall armyworm (Lepidoptera : Noctuidae), and southwestern corn borer (Lepidoptera : Crambidae) in a laboratory bioassay

摘要

abstract_textpThe development of crop plants expressing genes that encode insecticidal proteins isolated from the bacterium Bacillus thuringiensis Berliner (Bt) has provided a tremendous opportunity for improved control of insect pests. Although corn, Zea mays L., germplasm with resistance in the whorl stage to fall armyworm, Spodoptera frugiperda (J. E. Smith), and southwestern corn borer, Diatraea grandiosella Dyar, larval feeding has been identified and released, little progress has been made in identifying resistance to ear damage by these insects. Husks and silks were collected 3 to 4 d after anthesis from nontransgenic and transgenic corn hybrids and used in laboratory bioassays to determine the effects of the Bt insecticidal protein on larval survival and growth of fall armyworm, southwestern corn borer, and corn earworm, Helicoverpa tea (Boddie). Southwestern corn borer larvae that fed on diets containing husks of transgenic plants did not survive. Corn earworm larvae fed on diets containing husks or silks from transgenic plants died, and those that fed on diets containing silks harvested from transgenic plants exhibited reduced survival and growth. Fall armyworm larvae were least susceptible to the Bt protein, but larval survival and growth on diets containing husks of transgenic plants were reduced. Larval growth also was reduced on diets containing silks from transgenic plants. The bioassays indicated that expression in husks and silks of genes encoding Bt insecticidal proteins could be useful in reducing insect damage in ears of corn./p/abstract_text