WSU Extension

Washington State Impacts

Washington State University -- Impact 2008
Exploiting the Chemical Language of Plants to Improve Biological Control


An entomologist at Washington State University is developing a novel strategy for controlling mites and insects in hops, grapes that employs synthetic versions of volatiles, or odors, that plants emit when they come under attack. The volatiles attract predators and parasitoids of pests providing the opportunity for more timely and reliable biocontrol. Still in its infancy, this research could greatly improve biological control of insects in mites in hops and grapes as well as other crops in the Pacific Northwest and throughout the world.


When attacked by pests, plants produce chemical distress signals that may alert natural enemies of the pests that food is available or inform neighboring plants of impending attack. By raising a "stink," plants attract natural bodyguards to help them survive. By exploiting this "chemical language" of plants, we may be able to increase levels and reliability of biological control in crops.


David James, an entomologist at Washington State University's Prosser Irrigated Agriculture Research and Extension Center, has been investigating synthetic versions of herbivore-induced plant volatiles as a means for attracting predators of pests. He has found that that a number of insects that are predators of mites and insects in hops and grapes were attracted by methyl saliciylate and hexenyl acetate. Tests showed that vineyards and hop yards baited with slow-release dispensers of methyl salicylate, an ingredient found in toothpaste, candies and a variety of household products, recruited larger numbers of predators than non-baited yards. In some instances, sufficient numbers of predators were recruited to allow production of hops without the application of insecticides and miticides.


Before this method, called Herbivore-Induced Plant Protection Odors, or HIPPO, can be put to practical use, scientists still need to answer questions about deployment rate and method of deployment as well as about the mode of attraction because some HIPPOs may work by signaling crops to produce their own blend of predator attractants. Although this research is still in its infancy, it appears to show great potential for making great strides in improving biological control of insects and mite pests of crops around the world.




Wa. Commission for Pesticide Registration
Hop Research Council
Washington Hop Commission
Wine Advisory Board
Hatch Act


The principal counties served are Benton, Chelan, Franklin, Grant, Kittitas, Multi-state, Walla Walla, Yakima


David G. James, Associate Entomologist/Extension Entomologist
Washington State University
509-786-9280 (Phone)
509-786-9370 (FAX)


WSU Extension, PO Box 646248, Hulbert 411, Washington State University, Pullman WA 99164-6248, 509-335-2837, Contact Us