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New Corn Lines Resist Aflatoxin, Weevils
By Linda Cooke
February 13, 1998
New corn breeding lines developed by Agricultural Research Service scientists have built-in resistance to an insect pest that attacks stored corn and makes it more susceptible to aflatoxin contamination.
The new lines, developed by ARS scientists at Mississippi State University, resist Aspergillus flavus, a fungus that produces aflatoxin in corn. Entomologists at the ARS Grain Marketing and Production Research Center in Manhattan, Kan., found that some of these corn lines resist maize weevils.
Weevils damage corn by chewing holes in the kernels and laying eggs in the holes. When the larvae that hatch from the eggs feed in the kernels, their metabolism creates heat and moisture--conditions that make it easier for A. flavus to grow and produce aflatoxin. That's why it's important to combine fungus and weevil resistance into new corn breeding lines.
The resistant lines won't stop all the fungi or weevils, but will greatly reduce their growth, helping industry reduce costs of controlling stored product insects. The maize weevil is a major pest of stored corn throughout the world, so worldwide savings should be much greater.
To stop this pest and others, the scientists are currently looking for resistance to storage pests in all U.S. corn hybrids sold by Pioneer Hybrid International.
The researchers are also evaluating resistance to maize weevils in corn lines at USDA's Germplasm Enhancement of Maize (GEM) collection in Ames, Iowa. They are testing the six lines in GEM that are used most by commercial companies to develop new corn hybrids. The researchers hope to chemically pinpoint what makes the GEM lines thwart weevil growth. This discovery should lead to a quick, one-day test for weevil resistance that could substantially reduce the eight to 10 years now needed to breed resistant varieties.
Scientific contact: James E. Throne and James E. Baker, Grain Marketing and Production Research Center, Manhattan, KS 66502, phone (785) 776-2796, fax (785) 776-2792, throne@usgmrl.ksu.edu or baker@usgmrl.ksu.edu.
