A Little Bit of Egg Makes Tracking Aphids Easier

The green peach aphid, despite its name, is a pest of potatoes. Besides siphoning off juices from potato plants, the aphid can infect the plants with viruses that cause an estimated $100 million annually in yield losses.

Now, tracking where and when the aphid is likely to transmit potato viruses could be easier to do, thanks to a new marker technique devised by Agricultural Research Service (ARS) entomologist Tom Unruh. His approach--which uses egg whites, plastic-mesh screens and an antibody-based test--is still experimental. But, ultimately, information derived from its use could help potato growers improve the timing of insecticide application to deter virus-laden aphids from feeding on plants.

Unruh devised the technique to support studies to determine whether virus-carrying aphids are flying into potato fields from nearby weed patches. Existing methods of capturing and marking the dash-sized pests have been difficult and unreliable, according to Unruh, with the ARS Yakima Agricultural Research Laboratory in Wapato, Wash.

His solution involved mixing egg-white proteins with water to create a solution that can be sprayed onto potato plants or associated weeds like nightshade. Aphids pick up the egg proteins while crawling over treated areas. To track them, Unruh relies on wide-mesh screens secured below a teepee-like scaffold that can be placed in or near potato fields. An adhesive holds the aphids so they can be returned to the laboratory for analysis using an immunological assay, which employs antibodies to detect egg proteins if they're present.

In fields near Wapato, more than 50 percent of green peach aphids that contacted treated potato plants tested positive for egg proteins. More field tests are under way.

Read more about this research in the May/June 2008 issue of Agricultural Research magazine.

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