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Computer Figures Stored-Grain Insect Risk

Next July, a Kansas farmer stores wheat with a moisture content of 12 percent and a temperature of 90° F in a grain bin.

After entering the storage information into his personal computer, a program called Stored Grain Advisor (SGA) indicates he will need to be wary of damaging insect infestations if he plans to store the grain past mid-September.

SGA helps the grain manager select the most appropriate control methods. According to the scenario, the program recommends sampling for insects 1 month after harvest and cooling the grain with aeration in September to possibly avoid a need to fumigate with an insecticide.

"We developed the SGA program as a decision-making aid that should help grain managers refrain from using pesticides unnecessarily, while maintaining quality in their product," says Paul W. Flinn, an ARS biologist at the U.S. Grain Marketing Research Laboratory in Manhattan, Kansas.

The software, available to farmers and grain elevator operators, is designed to run under Microsoft Windows on an IBM-compatible personal computer.

It will be distributed this summer through extension programs at Kansas State, Oklahoma State, and Montana State Universities.

SGA uses computer models to predict insect population growth, degradation of insecticides, and the effects of grain fumigation.

Besides serving as a management tool, SGA is also an educational tool. Grain managers can get information on how to sample grain for insect pests and how to identify the insects they find. An insect identification icon allows the user to view pictures of 16 of the most damaging insects in stored wheat, along with descriptions of the pests and the damage they inflict.

Another SGA module graphically predicts how different management choices—for example, time of fumigation—affect population growth of specific insects.

Flinn and ARS entomologist David W. Hagstrum confirmed the accuracy of SGA using data from some 50 different grain bins in Kansas and Oklahoma. In each of 3 years, they sampled grain monthly from June through January for insects, temperature, moisture, test weight, and insecticide residue. Insect pests they most frequently saw were rusty grain beetle, lesser grain borer, red flour beetle, and saw-toothed grain beetle.

The model was correct 80 percent of the time in predicting which bins would become infested with low, moderate, or high insect densities, and it was not biased in over- or under-predicting.

Rarely did wheat become infested with insects when it was stored at moisture levels of less than 10 percent and aerated to less than 68° F early in the fall.

Future enhancements the scientists plan for SGA include addition of other grains besides wheat and the ability to forecast economic consequences of different management actions. — By Ben Hardin, ARS.

Paul W. Flinn is in the USDA-ARS Biological Research Unit, U.S. Grain Marketing and Production Research Center, 1515 College Avenue, Manhattan, KS, 66502; phone (785) 776-2707, fax (785) 537-5584.

"Computer Figures Stored-Grain Insect Risk" was published in the June 1995 issue of Agricultural Research magazine.