Wasps might be the perfect weapon to kill aphids

(Credit: Matt Kaiser/Iowa State)

The best way to fight soybean aphids might be to bring in a species of stingless wasp that eats them.

It’s similar to a tactic adopted recently near Fairfield, Iowa, where officials hope a different species of wasp will limit the spread of the emerald ash borer.

Aphis glycines
A soybean aphid on a soybean plant. (Credit: Claudio Gratton/University of Wisconsin)

Matt Kaiser, a pre-doctoral associate in the Iowa State University entomology department, says controlling pest species by the introduction of other organisms is known as importation biological control, and scientists take great care to make sure the process doesn’t make a bad situation worse.

“If there’s a pest causing harm to humans or the environment, you can find other organisms that reduce that harm by suppressing the pest’s population. That’s what we refer to as biological control,” Kaiser says.

Native to Asia

Aphids emerged as a serious threat to Iowa soybeans around 2000. The insects are native to Asia and most likely came to the United States as unintentional international travelers on plants brought into the country. In the years since, aphids have caused soybean farmers major headaches by reducing yields by 40 percent during outbreaks and leading to a 130 percent increase in insecticide use in affected fields.

Kaiser is working with Matthew O’Neal, an associate professor in entomology, to study the viability of using Aphelinus glycinis, a species of tiny stingless wasps, to suppress aphids. Soybean farmers in Asia don’t experience the same difficulties with the pest, and Kaiser says that may be due to the presence of the parasitic wasps keeping the aphids in check.

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Kaiser and O’Neal are members of a team leading the release of the wasp to an initial limited number of soybean fields on research farms this summer. If the results are favorable, biological control may present Iowa farmers with a new means of reducing losses caused by soybean aphids at no or little cost.

Kaiser says biological control strategies range from relatively nonintrusive and temporary changes to a site to permanent introductions of new species. And insects aren’t the only species that scientists have tapped for biological control purposes. Nematodes, fungi, and other pathogens also have proven useful for biological control, he adds.

Source: Iowa State University