Image used with
permission from the
Zapping Insects With Radio Waves
By Marcia Wood
March 31, 2003
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.