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Recruiting pests’ natural enemies

New pest control tools for orchards are on the way from Washington State University.Look for new weapons in the arena of herbivore induced plant volatile, or HIPV, as WSU grad student Shawn Steffan furthers his fieldwork.

HIPV relates to herbivore feeding on plants, he explains. When plant eaters consume plants, it produces a chain of chemical reactions releasing volatile compounds.

“As a result, plants put out an alarm call that diffuses through their community, sounding a dinner bell for natural enemies of the pest,” says Steffan.

Key Points

• New research shows beneficials can be monitored.

• The study also focuses on manipulation of populations.

• Larger numbers of beneficials are being found than anticipated.

Essentially, the scenario tells beneficial enemies of plant pests where food can be found, he adds. “One of the most important keys to how natural enemies hone in on pests is in these volatile compounds,” Steffan says.

These compounds have now been isolated in the lab, and Steffan is using those materials to monitor natural pest enemies in the orchard.

“Until now, there has been no efficient way to monitor natural enemies,” he says. “We have pheromone lures that are great for monitoring the pests, but we have no idea of what’s out there in natural enemies.”

His monitoring program tells what beneficials are present, how many and when they are present. As a result, Steffan has found that the beneficial diversity in the orchard is much larger than expected. “This is remarkable,” he says.

This information results from the ability to lure beneficials, something that has not been done in earlier research, he says, when growers depended on sampling insect populations by striking trees and checking what falls out.

“That’s a tried-and-true method, but it is a bit crude,” he says, “and it does not give you a broad-spectrum assessment of what is in the orchard,” he says.

plan your sprays, you can program in what is going on with natural enemies. This can enhance a grower’s Integrated Pest Management effort.

“You have the information available to help minimize destruction of natural enemies in the orchard,” he explains.

Additionally, research in the early stages is focusing on the potential of using the lure to marshal beneficials to particular spots in the orchard where they are most needed. “There are potentially some very powerful applications here,” he says. “Perhaps we can bring the natural enemies to a pest hot spot, concentrating biocontrol where it is most needed.”

In test traps used in the study, he found “clouds of lacewings” circling lures where sticky traps were not used, allowing the attracted beneficials to gather freely.


GOOD BUG BONANZA: WSU researcher Shawn Steffan is finding a surprisingly large number of beneficials on insect collection liners he has placed in test orchards.

This article published in the September, 2010 edition of WESTERN FARMER-STOCKMAN.

All rights reserved. Copyright Farm Progress Cos. 2010.