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Ivan Hiltpold of the University of Delaware.

Research targets western corn rootworm

If you know anything about raising crops, you know that insects and weeds constantly evolve and build resistance to existing methods of controlling them

Now, new research targets the western corn rootworm — sometimes known as the "Billion Dollar Bug" because of the enormous damage it does — by using one pest's resistance against it.

The research involves nematodes that are chemically attracted to feed on western corn rootworm that have built up resistance to Bt corn.

"These nematodes are beneficial to the (corn) plant because they're killing the insect," said Ivan Hiltpold, assistant professor of entomology and wildlife ecology at the University of Delaware.

He and the U.S. Department of Agriculture's Bruce Hibbard, who leads plant genetics research at the University of Missouri, worked on the research. Hiltpold studied at the University of Missouri before joining the University of Delaware in 2016.

Their fundings were published in the Journal of Economic Entomology. The abstract can be read at https://academic.oup.com/jee/article-abstract/111/5/2349/5063818?redirec....

A little background:

Farmers have planted hybrid corn plants that are genetically engineered with a bacterium called Bacillus thuringiensis, or Bt, that produces toxins. That toxins kill susceptible rootworm that attack the corn plant, limiting the damage.

But over time, the rootworm developed resistance to the toxins, reducing their effectiveness.

The research by Hiltpold and Hibbard uses that resistance against the rootworm. In their approach, the rootworm-damaged plants send out a chemical signal to attract nematodes, multicellular animals often known as roundworms. The nematodes, in turn, begin feeding on the rootworms.

"It's using the ability of the plant to defend itself to help the situation," Hiltpold said.

Some types of nematodes can do terrible damage to crops. "But these nematodes aren't doing anything harmful at all to the plant, only beneficial," Hiltpold said.

Could the nematodes, over time, evolve and begin doing damage to corn plants?

Hiltpold said doesn't think that's a serious concern. Corn fields already are a "heavily manipulated environment. Adding nematodes will not be too much of a problem. They may live a crop season, or two or three, then they tend to die."

Upper Midwest impact?

It's unclear how the research might affect Upper Midwest corn production.

A spokesman for the Minnesota Corn Growers Association said his organization doesn't have the expertise to comment on the research.

Randy Melvin, a Buffalo, N.D., farmer and president of the North Dakota Corn Growers Association, said that, in general, western corn rootworm is a growing concern in the Upper Midwest, especially in areas where corn-on-corn is common, and that many farmers are interested in new ways to combat it.

Ideally, the research will be most beneficial to corn breeders, who can use it in their work developing new varieties, Hiltpold said.

Delaware's sandy soil limits the damage that western corn rootworms cause in the state, so Hiltpold doesn't anticipate doing much more research targeted toward corn. But he may continue the research to help in the fight against rootworms that hurt watermelons, a major crop in the state.

His takeaway from the research:

"You don't need crazy new big ideas. You just need to think a little outside of the box," he said.

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