War on weevils

Company aims microwaves at farmer's tiny enemies
By Carla McCann
Janesville Gazette Staff

CLINTON--Steven L. Halverson hopes to someday be a leader in the mass extermination of weevils.
It's not a personal vendetta, or anything of that sort, that drives this 70-year-old retired electrical engineer in his commitment to create a heavy-duty weevil exterminator.
It's a labor of love," Halverson said. "I was born on a farm in Kewaskum. I have farmer roots and have always had an empathy for the problems of the farmer."
Halverson, president of Micro-Grain Inc. of Clinton, formed the company to research the use of microwaves in killing insects in stored grain. His plan is to build a microwave unit that will zap weevils while the grain is being transported by elevators into storage facilities.
The dead adult weevils could be removed from the grain through a sieve. The larvae, however, would be milled, Halverson said.
Originally, I was thinking in terms of drying grains using microwaves," Halverson said. "Then I became aware of efforts being made to control insects by non-chemical means. I knew microwaves could be applied toward that end."
His goal is to find an alternative to chemical pesticides now used in the control of insects in stored grain and stored-grain products.
No mother wants to feed their children food laced with
pesticides," Halverson said.
The adult weevils lay eggs in the grain. The larvae also cause great damage to the kernels.
"Globally, about 20 percent of stored grain is lost to weevils," Halverson said. "In the United States, because of integrated pest management strategies, the loss is 5 to 10 percent."
Since World War II, the first line of attack against weevils has been chemical pesticides, Halverson said.
In attempts at self preservation, weevils--like other insects--have evolved and developed a resistance to many of the chemical pesticides, Halverson said.
The Environmental Protection Agency is banning one fumigant that still carries a punch, methyl bromide, by 2001, Halverson said.
Methyl bromide mostly is used in pre-harvest applications, but it also is used in stored products, Halverson said. His research shows that high-power microwaves can kill insects in stored grain efficiently and economically, Halverson said.
"Insects have no known resistance to microwaves, and microwaves have no known effect on humans at the levels outside of the applicators," Halverson said.
Halverson is working with entomologists Wendell E. Burkholder and Rudy Plarre of the U.S. Department of Agricultural Research Service Stored Product Insects Research Unit at UW-Madison to find optimum frequencies and temperatures for microwaving grain weevils that will not destroy the quality of the grain being treated.
Preliminary studies have been successful in killing 100 percent of the adults and older larvae in samples of soft white wheat. The younger larvae are less susceptible to the microwaves but can be killed. It just requires a greater energy input, Halverson said.
"Insects contain more moisture than grain does," Halverson said. "Microwave energy applied to the grain as it falls into storage kills the insects without cooking the grain."
He has experimented at the Oak Ridge National Laboratory in Oak Ridge, Tenn., with prototype applicators. Information gathered from those experiments will help Halverson design more sophisticated equipment, he said.
Halverson has filed for a patent on the microwave design. The next step is to build a demonstration unit, he said.
The ultimate goal would be to treat 10,000 bushels of grain an hour, he said.
But we're nowhere near that goal," Halverson said. "Our first pilot plan will treat about 1 '000 bushels an hour. It's a start."
The first part of the research was paid for by a $50,000 grant from the U.S. Department of Agriculture.
"If you count the total labor, we've got about one-half million involved in this research," Halverson said. "The grant allowed us to hire some contractors."
He will apply for a second grant from the Department of Agriculture to pay for the next step in the research.
"We're expecting about one quarter of a million dollars," Halverson said. "If we have all of our other commitments in place, we could get an additional $200,000 for the project."
The DeLong Co. Inc., which stores and processes grain, is less than a mile from Halverson's home. When the first microwave unit is ready, it likely will be installed at the DeLong Co. for field trials, Halverson said.
Halverson and his colleagues will report their findings in August at the international meeting of the American Society of Agricultural Engineers in Minneapolis.