A group of researchers, led by Washington State University food engineer Juming Tang, continues to make progress on a quick way to treat dry commodities, such as nuts, for storage pests.
Since 2000, they have looked at radio frequency and how it might be a possible alternative to methyl bromide to disinfest nuts and legumes, according to a news release.
Other possible methyl bromide alternatives include controlled atmosphere treatments, but they typically require exposure times of several days.
Cold storage, conventional heating and irradiation also have drawbacks.
Radio frequency treatments harness high-frequency electromagnetic waves to rapidly heat agricultural products and the pests inside.
Lethal exposure times are minutes rather than days.
Because the exposure time is relatively short, product quality isn't compromised.
The group has conducted several studies that examined mortality of codling moth, navel orangeworm, Indianmeal moth and cowpea weevil through all life stages.
Their research showed complete insect mortality in 4 to 10 minutes at temperatures of 50-60 degrees Celsius—122-144 Fahrenheit.
The group then expanded the work and validated the treatment for insect control of in-shell walnuts at a large commercial facility in California.
They have since expanded the research to include legumes, raisins and other dry commodities.
Also involved in the work are engineers, entomologists and plant physiologists from the University of Califoria, Davis, and U.S. Department of Agriculture's Agricultural Research Service in Washington, Califorina, Texas and Hawaii.