Pesticide and Environmental Update
Zapping Insects With Radio Waves
By
Marcia Wood
Wiggly, wormy insects that would like to hide inside nuts and dried
fruits succumb to heat generated by radio waves. Researchers, in fact, have
known this for decades. Now, however,
Agricultural Research Service scientists and their university colleagues
are taking a new look at using radio waves to clobber pesky insects in these
crops at packinghouses and processing plants.
ARS research entomologist Judy A. Johnson, based at Parlier, Calif., and
collaborators at the University of
California at Davis and Washington State
University at Pullman are evaluating the technology's potential use as a
safe, effective substitute for methyl bromide fumigant. Methyl bromide is
being phased out in the United States.
Johnson's studies at ARS' San
Joaquin Valley Agricultural Sciences Center target navel orangeworm and
Indianmeal moth. Those insects are among the worst enemies of walnuts,
almonds and pistachios and of dried fruits such as figs and raisins. In
addition, Johnson is scrutinizing another culprit, the red flour beetle.
Though a lesser pest of nut and fruit crops, the beetle is a major problem
in flour mills and food-processing plants.
In studies conducted over the past two years, the scientists have
developed a preliminary picture of the troublesome insects' thermal
tolerance--that is, their ability to endure heat generated by the radio
waves. These laboratory experiments are the first to extensively detail the
thermal tolerance of the navel orangeworm and Indianmeal moth.
For one test, Johnson and co-investigators drilled tiny holes in more
than 500 in-the-shell walnuts, enticing the slender, whitish navel
orangeworms to enter the shells. The scientists then plugged the holes and
heated the walnuts with radio waves, hot air or both.
All the treatments killed 100 percent of the navel orangeworms. Also,
tests led by Johnson's collaborators showed that the treatments didn't harm
the quality of the walnuts.
ARS is the U.S. Department of Agriculture's
chief scientific research agency.
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