The western tarnished plant bug feeds on several important crops. Research shows that using certain volatile compounds could improve biological control of the pest. Photo by Jack Kelly Clark, courtesy University of California Statewide IPM Program.

To Catch a Pest, Scientists Fine-Tune Traps

By Laura McGinnis
November 28, 2006

Airborne volatile compounds that attract plant-feeding insects to alfalfa could help growers control cotton pests with fewer pesticides.

That's according to Agricultural Research Service (ARS) entomologists Jackie Blackmer and John Byers, at the agency's U.S. Arid-Land Agricultural Research Center in Maricopa, Ariz.

Working with Cesar Rodriguez-Saona of Rutgers University, they investigated the influence of volatiles—or chemical scents—on the western tarnished plant bug (WTPB), a pest that feeds on several important crops, including cotton.

Existing control options are extremely limited. Traps can be helpful pest management tools, but their success hinges on knowing exactly how to lure a particular insect. Often, that means enticing them with chemical signals, such as sex pheromones, but researchers have not yet developed an effective WTPB pheromone trap.

So what else attracts these insects? What kind of "carrot" could draw them into a sticky trap?

The scientists' studies show that female WTPB are drawn to alfalfa volatiles and chemically manufactured synthetics that have most of the characteristics of natural chemical scents. This information could be used to develop more effective field traps baited with volatiles.

Volatiles can add flavor to food, and fragrance to perfumes and scented cosmetics. Plants use them to attract and repel insects, but insect responses to them vary.

Another study combined the chemical cues with a green-light-emitting diode (LED), which imitated a visual cue that attracts plant-feeding insects. Alone, the LED drew several females, but when combined with volatile or synthetic cues, it attracted both males and females at all stages of maturity. In some tests, the LED-synthetic compound combination drew positive responses of 80 percent or higher.

In field tests, one chemical compound proved to be particularly promising at drawing WTPB to the traps. Although the traps currently capture some beneficial insects as well, the scientists hope further research will allow them to develop a more target-specific model.

ARS is the U.S. Department of Agriculture's chief in-house scientific research agency.