Daniel Pavuk displays a wasp from the genus Megarhyssa, one of the largest parasitoids found in this part of the country. This insect uses its four-inch-long ovipositor to drill into softwood trees and lay an egg. After hatching, the young parasitoid feeds on a host sawfly, the pigeon tremex, that tunnels in the tree.

BGSU biologist seeks plants that attract crop pests’ natural enemies

As farmers plant their crops for another growing season, they also prepare to do battle with the pests that would—and do—eat into their livelihood.

They use insecticides, with varying degrees of success, against enemies with names like European corn borer and bean leaf beetle. And they’re always looking for new weapons such as Bt (for Bacillus thuringiensis) corn, a strain that has been developed and shows promise in the fight against the corn borer.

But research also continues into natural approaches to crop pest control, some of it by attackers as small as one-sixteenth-inch long.

“There’s still a lot of potential to look at pest control without chemicals,” says Daniel Pavuk, biological sciences. Awareness of natural controls goes back thousands of years, but the question now is how to implement them in a time of larger fields and equipment, adds Pavuk.

Along with current and former graduate-student collaborators Melanie Bergolc, Nathan Fries, Kelly Hite-Bechstein, Rhonda Oates, Laura Hughes-Williams and Christine Warner, he has been trying to identify plant communities on the edges of corn and soybean fields that may enhance populations of small parasitoids—mainly wasps—as well as spiders and predatory insects that are important biological adversaries of row crop pests.

The premise, Pavuk says, is that more complex edges, meaning fence or hedge rows or wood lots adjacent to fields, may attract more of the helpful insects. Those habitats can also benefit birds and other wildlife, in addition to helping with soil erosion, but few remain in the Midwest, he notes.

Even in a “simple-edge” environment, however, research has indicated that flowering, weedy plants like Queen Anne’s Lace lure insect enemies of crop pests, says Pavuk.

One such “true bug,” he says, is a one-sixteenth-inch predator that feeds on corn borer eggs, aphids, and spider mites, which create problems in soybeans particularly under dry conditions.

While parasitoids can be flies, most are wasps one-quarter to one-half inch in length, Pavuk explains. Some attack caterpillars, while others, depending upon the species, attack eggs. They lay eggs in the host insect, and after the eggs hatch, the tiny wasps eat the host and emerge, not unlike the creature in “Alien,” he says.

Although considerable research has been done on such beneficial insects worldwide, more extensive study is still needed, says Pavuk, whose interest in natural control of problem insects dates to his years as an entomologist for the Ohio grape industry in the mid-1980s.

Two of his projects—one started last year and the other scheduled to begin this year—have further implications for natural regulation of crop pests. The ongoing study is investigating the effects of forest fragmentation in northwest Ohio on moths and their parasitoids. The upcoming, large-scale project will examine ground beetles found in forest fragments and their movement into crop fields, where the mostly predatory insects feed on a variety of insect pests.

“The research that we do doesn’t require a huge amount of money,” Pavuk points out, and working through extension offices in Wood and Henry counties, “it’s been easy to find people” to host it on their farms. He may try to do further plot research in conjunction with Ohio State University, where he earned his master’s and doctoral degrees in entomology.

Considering the uncertainties of weather and world trade, not to mention crop pests and disease, “it’s a tough way to go when you’re farming,” Pavuk says. But returning natural controls to agriculture—maybe even including production of helpful insects in a laboratory setting—would potentially benefit farmers and the land they cultivate, he maintains.

Creating habitats for beneficial insects would not only possibly reduce the use of pesticides, but also reduce soil erosion and may be a cost savings for farmers. Other benefits could include increased habitat for birds and alternate pollen and nectar sources for bees.

“Anything we can do to help them (farmers) and help the environment, we all win,” Pavuk says.