They're wormlike. Some of them are parasites. And they do wiggle. Although that description isn't exactly endearing, nematodes – microscopic animals – aren't all bad. They have the distinction of being the most abundant of earth's multicellular animals, and they play an important ecological role in prairie grasslands because they occupy key positions as primary and intermediate consumers in soil food webs, said University of Nebraska Plant Pathologist Thomas Powers.

"They are extremely responsive to physical disturbances in their environment, such as chemical pollutants or physical disruption of the soil structure," he said. "An entire community of nematodes can shift, some species increase and others die. They can be like canaries in a mine shaft, an early warning system saying, 'Hey, possibly there's a problem here.'"

His research focuses on plant parasitic and insect parasitic nematodes.

"It's fascinating to study something so seemingly insignificant and so small you can't see them, yet they've been on the face of the earth for hundreds of millions of years," Powers said.

Research on nematodes may enable scientists to make recommendations about ways to manage agricultural ecosystems using less or perhaps even no pesticides.

"I think it's important for people to understand that these seemingly insignificant organisms might have a very great impact on the way the world functions," Powers said. Powers and graduate assistant Peter Mullin are studying the linkages between nematodes above ground and those below ground. The Institute of Agriculture and Natural Resources researchers are trying to document all the nematodes in several undisturbed sites in the Konza Prairie, south of Manhattan, Kan. Considered leaders in the development of molecular techniques for nematode identification, they are part of a multidisciplinary, multi-university collaborative project examining the biological diversity of the Konza's ecosystem.

The Konza is in the Flint Hills. Because of its rocky terrain, it is much more barren than many grasslands. Yet, more species of nematodes have been recorded from the Konza Prairie than any other single site on earth, Powers said.

"What makes this study more distinctive is that we are photographing and documenting each and every nematode, and then smashing them and extracting their DNA," he said.

This is tedious work. About 20,000 species are classified as nematodes in the phylum Nemata. Approximately 2,000 to 3,000 nematodes live in a standard soil sample that is the equivalent of a "good handful of dirt." Out of the 384 species Powers and Mullin have identified so far, about 10 percent appear to be previously unidentified.

"It appears that there are more species of nematodes than anyone thought," Mullin said.

They also study nematodes at Nine-Mile Prairie northwest of Lincoln, the longest-studied natural area in Nebraska, and at Homestead National Monument near Beatrice, the second oldest restored prairie in the country. This gives them an opportunity to compare nematode communities in native and restored prairies.

"The primary focus of our research is nematodes that affect a managed ecosystem in some way," Powers said. These ecosystems can encompass agricultural land, rangeland, forests and home lawns.

Nematodes include plant parasites, fungal or bacterial feeders, predators and omnivores, which eat both plants and animals. Adults have only about 1,000 cells, but they have digestive, nervous, excretory and reproductive systems. Some live only a few days. Others have a 1- or 2- year life cycle. The largest are barely visible without a microscope. Some are hitchhikers, catching rides on insects. Some attack plants, animals or even themselves.

"Some nematodes have a remarkable ability to survive conditions that would kill other animals," Mullin said. "It seems that a lot of them have the ability to go through long periods of dryness and survive." This means they have the ability to affect ecosystems for a long time.

A National Science Foundation grant funds the Konza Prairie research.

– Linda Ulrich

Plant Pathologist Thomas Powers (left) and graduate student Peter Mullin take a soil sample at Nine-Mile Prairie near Lincoln as part of their research on nematodes. They focus on nematodes that affect a managed ecosystem, which can range from agricultural land to home lawns. They also study nematodes at the Homestead National Monument near Beatrice and at the Konza Prairie in Kansas.

In the laboratory, Mullin identifies and documents the nematodes with the help of molecular identification techniques.