Venom from a tiny parasitic wasp shuts down the growth of insect pests that cause millions of dollars of damage to many agricultural, vegetable and forage crops each year, scientists with USDA’s Agricultural Research Service report.

ARS scientists have isolated and identified the active ingredient in venom produced by the wasp Euplectrus comstockii. This wasp is a natural enemy of Heliothis pests--including crop-munching cotton bollworms, corn earworms, tobacco and tomato budworms, fall armyworms and cabbage loopers.

Before a female E. comstockii wasp lays an egg on Heliothis larva, she injects venom into the larvae. The venom stops the Heliothis larva from molting--shedding its skin--so it can’t develop. That’s important because 90 percent of the crop damage from these leaf-eating insects is done during the larval, or caterpillar, stage.

A team of ARS scientists demonstrated that only a small amount of the wasp venom was needed to halt development of a wide array of insect pests. Besides working against the Heliothis complex, the venom was also effective in stopping the growth of the European corn borer, an insect that causes $350 million losses each year. Testing the venom on the corn borer was important to show that it works on a wide variety of pests, including those that aren’t normally hosts for the wasp.

Now the scientists are planning field studies of an insect virus that can spread the venom among the crop pests. If these field tests are successful, the venom could be the basis for a new, natural pest control.

Scientific contact: Thomas A. Coudron, ARS Biological Control of Insects Research Laboratory, Columbia, Mo., phone (573) 875-5361 ext. 225, fax (573) 875-4261, entmtac@showme.missouri.edu.