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Radio Frequency Puts the Heat on Plant Pests

Although the effectiveness of using radio waves to kill destructive insects in agricultural products has been known for 70 years, the technique has never been applied on a commercial scale. For several decades, methyl bromide has been a mainstay treatment to kill a wide array of quarantined pests.

A recent cooperative effort by four Agricultural Research Service research laboratories and two universities aims to overcome the technical barriers to use of radio wave heating to control pests on a commercial scale in places such as orchards, packinghouses and food plants.

Electromagnetic waves of radio frequency can make molecules vibrate and heat up, in the same way that microwaves heat food. The trick is to kill pest insects without killing the taste or texture of the food they infest.

Since 2000, a team led by Juming "Jimmy" Tang of Washington State University (WSU) in Pullman, involving four ARS laboratories and the University of California-Davis (UC-Davis), has been working on a four-year study to see if radio waves would be an economical, environmentally friendly alternative to the use of methyl bromide and other chemicals to effectively rid fruits and nuts of live insects.

At the Kika De La Garza Subtropical Agricultural Research Center in Weslaco, Texas, ARS entomologist Guy J. Hallman is investigating the use of radio frequency treatment of citrus against the Mexican fruit fly. Hallman is developing a device to simulate what's needed to commercially heat-treat citrus fruit, such as oranges and tangerines, with radio waves.

In cooperation with a team led by Tang, a professor in biological systems engineering at WSU, James D. Hansen, an entomologist at ARS' Yakima Agricultural Research Laboratory in Wapato, Wash., plans to "bathe" tubs full of apples and cherries with radio waves to determine exposure times that will kill codling moth larvae without affecting the fruit's quality. Hansen is working with Stephen R. Drake, a horticulturist at ARS' Tree Fruit Research Laboratory in Wenatchee, Wash., and Lisa G. Nevens, an ARS entomologist at the Wapato laboratory.

Meanwhile, at the ARS San Joaquin Valley Agricultural Sciences Center in Parlier, Calif., entomologist Judy A. Johnson is testing the use of this technology to rid walnuts, almonds, pistachios, figs and raisins of the wiggly larvae of the navel orangeworm, Indianmeal moth and codling moth.

Read more about this research in the February issue of Agricultural Research magazine.

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