WEST LAFAYETTE, Ind. -- Wheat has ways to battle the tiny, red wormlike insects that nibble on the plant's leaves and can destroy crops worldwide, but the Hessian fly larvae that survive eventually evolve methods to overcome plant defenses.

Purdue University and USDA-Agriculture Research Service scientists trying to thwart the insect have identified Hessian fly genes that nullify toxins that wheat produces to protect itself from the munching larvae. The researchers report their findings in the Feb. 6 issue of the journal Proceedings of the National Academy of Sciences.

Richard Shukle, a USDA-ARS entomologist and Purdue adjunct assistant professor, is working with colleagues to learn more about how the flies feed and why they can't establish a feeding site on plants that are resistant to the larvae.

"The focus of our work is to try to understand how the insect overcomes plant resistance and use that basic knowledge to enhance the durability of wheat against Hessian fly attack by combining several genes for resistance or through some other novel strategies," said Shukle, senior and corresponding author of the paper.

The toxic oxygen compound defense mechanism in resistant plants stresses the larvae, which then fight back, he said. This is confirmed by the Hessian fly larvae's increased production of enzymes triggered by their antioxidant genes in order to detoxify wheat anti-insect poisons.

"Hessian fly larvae are under stress when they encounter resistant wheat plants," Shukle said. "This stress includes starvation when they can't establish a feeding site. The larvae also are under stress from toxic molecules, including poisonous oxygen compounds."

Researchers know little about the biochemical mechanisms involved when larvae - the early stages of the gnat-sized Hessian fly - try to feed on resistant wheat plants that are able to defend themselves, Shukle said. While the insects can't establish feeding si
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Contact: Susan A. Steeves
ssteeves@purdue.edu
765-496-7481
Purdue University
7-Mar-2007