Apple, pear and walnut growers will soon have a new tool to control codling moths, thanks to Agricultural Research Service scientists and a commercial company.

ARS entomologist Douglas M. Light discovered that one of the chemicals responsible for a pear's sweet odor, known as the pear ester, attracts both female and male codling moths. Light works at the Plant Protection Research Unit of ARS' Western Regional Research Center (http://www.pw.usda.gov) in Albany, Calif.

Codling moths are the most severe and widely distributed pest of apples, pears and walnuts in the world. Uncontrolled, the larvae — the “worm in the apple” — can destroy up to 95 percent of an apple crop and up to 60 percent of a pear crop. In walnuts, the larvae damage the nuts and create holes in the hull and shell that can allow fungi to enter.

Pheromones, sex hormones produced by the females, are widely used in monitoring and mating disruption programs, but only attract male moths. Researchers estimate that 90 to 95 percent of male codling moths in an orchard must be trapped or prevented from finding a mate to reduce the number of fertile eggs laid by females to an economically manageable level. Capturing female moths has an even greater potential to reduce offspring without widespread spraying of chemicals.

Through a cooperative research and development agreement, Trece, Inc., of Salinas, Calif., is developing commercial monitoring tools using the pear ester. Trece also plans to include the attractant in a sprayable lure formulation known as an “attracticide,” which contains small amounts of insecticides.