November 21, 2002

NDSU Researchers Learning to Lure Sunflower Pests

Fake sunflowers and moth antennae hooked to electronic sensors are helping North Dakota State University researchers learn how to lure and kill females insects before they can lay eggs on sunflowers.

NDSU entomologist Stephen Foster is studying various pests of sunflowers, including sunflower midge and banded sunflower moths, to determine how they respond to chemicals from sunflower heads. His group is attempting to isolate the chemicals that attract the insects, manufacture them, and then determine what combinations and amounts elicit the largest responses of the insects.

Using attractant chemicals to lure insects is not new science, but most previous research has focused on attractants of male insects. "They have a limited effect on pest control in many cases," Foster says. "Even a few males that are not attracted to the synthetic mixes can find and fertilize a large number of females with little effect on the final number of pests. And for most insects, it’s the females that find the crop and the larvae that cause the damage. Our goal is to attract and remove the females in an environmentally safe manner before thy have a chance to infest a crop."

If successful, Foster’s research could pay huge dividends for sunflower producers. The sunflower midge and the banded sunflower moth are two of the pests considered among the worst threats to sunflower crops. And it’s likely that a similar approach could be adopted to control other insects in other crops.

Foster began the research with sunflower midge. "The sunflower midge has an intimate association with its host plant that precluded us from rearing the insect in the laboratory," Foster says. "We had to collect sunflower heads infested with large numbers of midge."

Next, Foster tested chemicals from a sunflower head to determine whether female sunflower midges were attracted to them. "More than 90 percent of the midges responded to the sunflower chemicals," Foster says.

Foster is also examining how chemicals in sunflowers are involved in host selection by female banded sunflower moths. Using "model sunflower" heads created by stretching felt across glass vials and treating them with these chemicals, he has found that the moths respond to both volatile and non-volatile chemicals.

Foster’s group is now isolating the sunflower chemicals that the moths respond to. One method they are using is called an electroantennogram, in which an isolated moth antenna is connected to two electrodes. As the active chemicals pass over the antenna, the antenna gives an electrical response that is recorded on a computer. They are then able to identify the electroantennogram-active chemicals from the myriad of chemicals produced by sunflowers that the moths do not respond to. Already they have identified five component chemicals, which will be tested for their ability to attract female moths.

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Source: Stephen Foster, (701)231-6444, stephen.foster@ndsu.nodak.edu
Editor: Tom Jirik, (701)231-9629, tjirik@ndsuext.nodak.edu
Writer: Scott Lowell, (701)231-7865, slowell@ndsuext.nodak.edu