Natural Product Helps Insects "Bite the Dust" - Brief Article

Agricultural Research, June, 2000

Remnants of one of the oldest things on earth--diatomaceous earth (DE)--may help solve one of today's most pressing problems: developing noninsecticidal controls for insects in homes and food-processing facilities. Consisting of the dust of fossilized skeletons of microscopic aquatic plants, DE is nontoxic to humans. But it kills red flour beetles and confused flour beetles--two of the food-processing industry's worst insect pests. It works by disrupting the insects' outer covering, or exoskeleton, causing them to die from rapid water loss.

Researchers have found that fluctuations in temperature and relative humidity can affect the performance of DE products, which proved most effective in controlling adult insects at higher temperatures and lower humidities. In tests, a 2-day exposure to DE at 80 [degrees] F and 57-percent relative humidity killed all red flour beetles, while it took a 3-day exposure to kill all confused flour beetles. DE is a possible alternative to methyl bromide, an ozone-depleting fumigant scheduled for phaseout by 2005.

Frank H. Arthur, USDA-ARS Grain Marketing and Production Research Center, Manhattan, Kansas; phone (785) 776-2783, e-mail arthur@usgmrl.ksu.edu.