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ARS Home » Midwest Area » Ames, Iowa » Corn Insects and Crop Genetics Research » Research » Publications at this Location » Publication #71745
Title: FIELD APPLICATION OF BACILLUS THURINGIENSIS BERLINER AND ANAGRAPHA FALCIFERA MULTIPLE POLYHEDROSIS VIRUS AGAINST THE COR EARWORM, HELICOVERPA ZEA (LEPIDOPTERA: NOCTUIDAE)

Author
item PINGEL, RANDALL - IOWA STATE UNIVERSITY
item LEWIS, LESLIE

Submitted to: Journal of Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: The corn earworm is one of the most destructive insects of vegetable crops in the United States. The earworm is particularly harmful in fresh market sweet corn, and without adequate control measures, 100% of the corn ears in a field may be infested. The pervasive and increasing problems associted with chemical insecticide use have led to the search for alternative forms of pest management of the corn earworm. This research tested the relative effectiveness of a bacterium and a virus, organisms that cause disease in insects only, as alternative controls for this pest of the corn ear. The compatibility of a starch-based additive with the efficacy of the disease-causing organisms was also evaluated. The application of the bacterium and virus to corn silks provided a significant increase in control of the earworm over untreated corn. Among the microbial treatments, the virus protected the corn ear as well as or better than the bacterium; and the starch-based formulations of virus and bacterium maintained their activity toward the earworm. The results of this research show that a bacterium and an insect virus have great potential to control corn earworms on sweetcorn and substantially reduce the applications of chemical insecticides. This research is a major step toward the goal of giving consumers quality sweet corn that is free of chemical insecticides.

Technical Abstract: The corn earworm, Helicoverpa (=Heliothis) zea (Boddie), is one of the most destructive insects of vegetable crops in the United States. The earworm is particularly harmful in fresh market sweet corn; 100% of the corn ears in a field may be infested if no appropriate controls are applied. Field evaluations were made of relative efficacy of applications of two subspecies of Bacillus thuringiensis (Bt) and Anagrapha falcifera multiple nuclear polyhedrosis virus (AfMNPV) to control laboratory-reared neonate H. zea on the corn ear. Also, the compatibility of a starch-based additive, a 1:1 mixture of starch (Mirasperse) and sucrose, when added to the entomopathogens was determined. The application of the three pathogens significantly decreased damage by H. zea and increased the percentage of corn ears with no damage and marketable ears; AfMNPV was as good or better than the Bt products in protecting the corn ear. The starch additive was determined to be compatible with the pathogens, although additional testin with AfMNPV is recommended.