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Model Helps Time Stored Pest Fumigation

Most U.S. warehouses fumigate three or four times a year to control moths and other stored product insect pests. Fumigation--costing about $20,000 each time--is initiated even when only two or three moths are sighted in the warehouse.

"Fumigating when there are so few insects is a costly waste," says Agricultural Research Service entomologist James E. Throne. He works at the U.S. Grain Marketing Production and Research Center in Manhattan, Kansas.

"Better timing can be achieved by having an accurate count of how many insects are present and knowing their stage of development. With this information, warehouse managers can keep costs down and reduce the amount of insecticide used."

Throne and entomologist David W. Hagstrum have developed a computer model for tracking development of the almond moth, a major pest of grain and other stored products throughout the world.

In 1996, using data gathered by Polish entomologist Jan Nawrot, ARS scientists developed a computer model that simulates the life cycle of almond moths on stored peanuts. Shortly after, they modified the model to simulate the moth's life on stored corn and dried citrus pulp. The basic data blocks of the model show how temperature and moisture conditions affect the number of adult moths, how many eggs each adult can lay, and how long it takes for immature moths to complete development.

"Our predictions can help warehouse managers decide when to use alternatives to insecticides. For instance, we know that cooler temperatures can reduce or stop moth reproduction and slow development of immature moths," says Throne. "It may take only a slight temperature drop, say from 75^oF to 65^oF, to curtail moth activity."

Turning on fans to cool down the warehouse is much less expensive--and more environmentally safe--than fumigating.

Now the researchers are adapting the computer model for predicting Indianmeal moth development in corn and other stored products that can harbor the pest. These moths are responsible for large expenditures by the multibillion-dollar food industry for sanitation and insecticidal treatments.--By Linda Cooke McGraw, Agricultural Research Service Information Staff.

James E. Throne and David W. Hagstrum are in the USDA-ARS Biological Research Unit, U.S. Grain Marketing and Production Research Center, 1515 College Ave., Manhattan, KS 66502; phone (785) 776-2796, fax (785) 776-2792.

"Model Helps Time Stored Pest Fumigation" was published in the July 1998 issue of Agricultural Research magazine. Click here to see this issue's table of contents.