Fungus may give farmers alternative

Kili Schwantes

An ISU entomology professor is conducting field experiments with a fungus that he said may eliminate the pervasive use of chemical insecticides and controversial genetically modified varieties of corn.

Leslie Lewis, professor of entomology, is working with entomology biological technicians Denny Bruck, graduate student in entomology, and Robert Gunnarson, technician with the U.S. Department of Agriculture. Lewis said they believe Beauveria bassiana, a fungus that naturally occurs in the environment, could effectively and safely combat the European corn borer.

Several Iowa farmers volunteered to let Lewis to spray their fields with the fungus in early July in 1998 and 1999.

Lewis said the corn borer travels upward and feeds on the shank of the ear and other parts of the plant, causing the stalk to weaken and making it difficult to harvest. The fungus kills the corn borer without harming the plant, he said, as he presented an insect covered with the furry white growth attached to an intact plant.

The goal of Lewis and his team is to further investigate how B. bassiana functions in the ecosystem. “We want to find out how it works, what we can do in nature to find out how it interacts in the ecosystem,” Bruck said. “We’re just trying to augment the system. We add granules that are coated with conidia [the fungal spore] and apply it to the corn plant.”

Bruck said the problem they are attempting to overcome is that the fungus is common but is not often found in high enough quantity to keep the corn borer below damaging levels.

Lewis said a benefit of the fungus use is that it may reduce cost to farmers because it stays in soil year after year. “Some of it stays until next season,” he said. “We’re trying to learn how it stays and how to get what’s in the environment to better express itself the following year.”

Gunnarson said there is an additional advantage with the use of this alternative pest control. “If you use it instead of an insecticide, the insecticide would not be running into water,” he said.

Since the fungus is not genetically modified, Bruck said, it could be of interest to organic farmers. “It gives farmers an alternative in pest control,” he said.

Dennis McLaughlin, a farmer from Cumming, has abstained from using chemical insecticides or genetically-modified varieties like Bacillus thuringiensis (Bt) corn. “We’re leaning toward organic, but we’re not there yet,” he said. “I just never felt the economic loss justified the use of pesticides.”

Ronald Brunk, a farmer from Eldora who had his field inoculated with the fungus at the same time as McLaughlin, said this method of pest control is preferable to the use of chemical insecticides.

Brunk said previously he had used pesticides and Bt corn, although the corn Lewis treated was not chemically treated or genetically engineered. “We [now] try to stay away from insecticides,” he said.

Some of the debate over the use of Bt corn emerged after a study was conducted on the mortality rate of the monarch butterfly larvae that fed on milkweed dusted with pollen from the genetically modified corn.