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ARS Home » Midwest Area » Ames, Iowa » Corn Insects and Crop Genetics Research » Research » Publications at this Location » Publication #71748
Title: FIELD AND LABORATORY EVALUATION OF TRANSGENIC BACILLUS THURINGIENSIS CORN ON SECONDARY LEPIDOPTERAN PESTS

Author
item PILCHER, CLINTON - IOWA STATE UNIVERSITY
item RICE, MARLIN - IOWA STATE UNIVERSITY
item OBRYCKI, JOHN - IOWA STATE UNIVERSITY
item LEWIS, LESLIE

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: The European corn borer is a serious pest in the Corn Belt costing farmers yield losses from $15 to $50 per acre of corn. With increasing restrictions on pesticides, the call for sustainable agriculture, and the mandate for less surface and ground water contamination, the demand has never been greater for innovative methods to control this pest. Transgenic ccorn hybrids with resistance to feeding by European corn borer offer a novel approach. Toxin-producing genes from a bacterium, Bacillus thuringiensis, that kills European corn borers are inserted into corn plants killing young corn borers as they feed. To determine the effect of these hybrids on non-target pest insects, larvae of the corn earworm, Black cutworm, common stalk borer and true armyworm were exposed to the transgenic plants. The plants delayed the development and survival of the true armyworm and the corn earworm with no effect on the common stalk borer ror the black cutworm. Transgenic plants are ushering in a new era of pest control that will reduce the use of chemical insecticides, however ongoing research is necessary to learn how to best use these plants. The results of this study show that these transgenic plants are effective against the primary pest but not other pest insects in the corn ecosystem. This research also shows that scientists must develop management plans for secondary pests of corn that are not controlled by current varieties of transgenic corn.

Technical Abstract: Field corn, genetically engineered to produce a protein derived from Bacillus thuringiensis kurstaki strain HD-1, (hereafter BT) was evaluated for its effect on larvae of noctuid species: Agrotis ipsilon (Hufnagel), Papaipema nebris (Geunee), Pseudaletia unipuncta (Haworth), and Helicoverpa zea (Boddie). No BT corn effects were observed on larval survival, pupal weight, or days to adult emergence for A. ipsilon or P. nebris; however, P unipuncta reared on BT leaf extract were 0.068g lighter in pupal weights, 8-days delayed in preimaginal development (from 33 to 41 d), and showed trends for 11-25% lower survival. Reduced survival and a 4-day delay in preimaginal development was also observed for H. zea reared on BT treated meridic diet. In 1994 and 1995, transgenic BT corn and non-BT corn seed was planted under field conditions. Eighty BT and non-BT plants were artificially infested with early instars of the 4 noctuid species and then evaluated for damage (leaf feeding, stalk cutting, ear-tip feeding). Ther were no differences between BT and non-BT corn damage caused by A. ipsilon. In 1994, P. nebris caused significantly less leaf-feeding damage to BT corn than non-BT corn. In addition, P. unipuncta and H. zea caused significantly less damage to BT corn leaves. Helicoverpa zea survived on and caused damage to BT corn ears and even though there were fewer ears damaged, there was no difference in the number of live larvae per plant on BT corn than non-BT corn.