Electrodes Help Find Beetles’ Favorite Scents

Several chemical scents that attract Colorado potato beetles have been discovered by Agricultural Research Service scientists. They attached tiny electrodes to the tips of beetles’ antennae so they could monitor the pests’ sensitivity to the scent of potatoes.

Colorado potato beetles are the potato crop’s most destructive pest, costing growers millions of dollars in chemical control and crop losses. For at least 73 years, scientists have been searching for the scent that attracts this yellow and black multi-colored bug to solanaceous plants.

Entomologist Joseph C. Dickens with ARS’ Vegetable Laboratory in Beltsville, Md., made the find while exposing the insects to different potato leaf aromas and allowing them to choose the scents they preferred.

When Dickens offered the beetles a choice between one of the scents and potato foliage, the beetles were terribly confused and could not tell the difference between the two attractive scents. He monitored the insects’ responses to both “real” and synthetic scents.

In preliminary field tests, the beetles were captured with a synthetic lure containing a mixture of these compounds. According to Dickens, no one had ever caught a Colorado potato beetle with a synthetic lure before. They have identified at least five different synthetic blends that are attractive to the insects in laboratory tests--and that may be attractive in the field as well. From this research, naturally-occurring chemical signals could be used to monitor and control pest populations.

Dickens is also investigating how chemical scents, which are emitted when the beetles chew on plants, might help attract potato beetle predators.

ARS is the chief scientific agency of the U.S. Department of Agriculture.

More information on this research appears in the February issue of Agricultural Research magazine.

Scientific contact: Joseph C. Dickens, ARS Vegetable Laboratory, Beltsville, Md., phone (301) 504- 8957, fax (301) 504-5555, jdickens@asrr.arsusda.gov.