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United States Department of Agriculture

Agricultural Research Service

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Helpful Roundworms Rescue Citrus From Evil Weevils

It’s tough waking up in the morning sometimes. But a cold, tangy glass of orange juice can help, along with a hardy breakfast.

But people aren’t the only fans of oranges. Take the citrus root weevil, for example. As a grub, it eats the roots of orange trees and other types of citrus, killing or weakening them. That, in turn, can mean fewer oranges for products like juice--or just to eat.

Recently, Agricultural Research Service (ARS) and University of Florida (UF) scientists discovered something interesting that could lead to new ways of fighting root weevil grubs.

Through laboratory experiments, the researchers showed that, when attacked, some citrus trees put out chemicals that attract wormlike organisms called nematodes.

Some nematodes, like the Steinernema and Heterorhabditis species, have a taste for the grubs, and feed on them from the inside out. After a few days, all that’s left of their prey is an empty shell filled with more nematodes ready to find new grubs to attack.

Often, chemical pesticides must be used to keep the grubs from harming trees. But the scientists are hoping to lessen the need for the chemicals by finding or even breeding varieties of citrus that can quickly attract their own army of grub-killing nematodes.

This pest-fighting strategy, called biological control, could also help protect the environment, since the nematodes occur naturally in the soil and generally only attack insect pests, like root weevils.

So next time you have a drink of orange juice, remember to thank these nematodes for their help--and their hunger!

By Jan Suszkiw , Agricultural Research Service, Information Staff

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Last Modified: 10/11/2011
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