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United States Department of Agriculture

Agricultural Research Service

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When Bugs Go Out To Eat

How would you like to have a job where you attach wires to insects and watch them eat? Some scientists do just that, and an Agricultural Research Service (ARS) scientist in California has come up with a better way to do it.

Aphids, leafhoppers, and some other insects feed by sticking pointed mouth parts called stylets into plants to reach fluids they need to survive. When the plant is punctured, it releases proteins and other chemicals to prevent those fluids from being pulled out.

Plants and insects are constantly at war with each other, but a lot of times the plant loses these battles and dies. That costs farmers billions of dollars each year in lost flowers, vegetables, fruits, and other crops.

Scientists like ARS entomologist Elaine Backus at the San Joaquin Valley Agricultural Sciences Center in Parlier, California, want to learn more about insect feeding. If they understand it better, they should be able to find better ways to prevent insects from destroying a farmer’s crops.

Much of the action takes place inside the plant, so it’s hard to see. To help them, scientists use a device that reads tiny electrical charges produced by the insect as it feeds.

It’s called an Electrical Penetration Graph or “EPG.” To use one, a researcher glues a wire to the insect’s back and inserts another wire into the soil near the root of the plant.

The wires establish an electrical circuit. Fluids in the insect and the plant carry electrical charges, and when the insect feeds, the
movement of the fluids causes the levels of those charges to fluctuate. Those fluctuations give scientists a picture of what’s going on.

Until now, EPG monitors have been able to study either large insects or small insects, but not both. But Backus and her University of Missouri colleague, William Bennett, developed a monitor with settings that can be adjusted to the sizes of different insects.

Scientists can use the EPG monitor to study not just aphids and leafhoppers, but ticks, mites, mosquitoes, stink bugs, bed bugs, deer flies, or any biting or chewing insect that pierces the surface of a plant or animal.

That’s important because there’s a whole world of insects out there, and they’re all just waiting to eat and be studied.

By Dennis O’Brien, Agricultural Research Service, Information Staff

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Last Modified: 1/3/2012
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