Fungi, Sex Drive Could Help Thwart Costly Nematode Worms

Tiny, plant-parasitizing worms called nematodes could face a new set of natural controls.

Fungi, plus the worms’ own sex drive and other tactics may help turn the tables on the pests, according to the Agricultural Research Service, the principal research agency of the U.S. Department of Agriculture.

In the U.S, soil-dwelling nematodes cause estimated losses of $9 billion annually from decreased food, fiber and ornamental production. But ARS’ Nematology Laboratory in Beltsville, Md., is a hub for developing state-of-the-art nematode controls.

Among several projects with promising results, Beltsville scientists have seen encouraging findings in studies with fungi and sex attractant chemicals.

The scientists collected 250 different fungi from areas of China where soybeans were first cultivated. They screened many of the fungi in the lab to help determine how they might be used against nematodes. One fungus, they found, secretes compounds that reduce egg hatch of root-knot nematodes by 80 percent compared with a control group of nematodes.

Female nematodes emit attractants, or pheromones, to attract males. The scientists found that some forms of the female soybean cyst nematode’s sex pheromone have potential to control the pests by disrupting their communication. The pheromone may also be used to prevent young nematodes from finding plant roots.

Root feeding by nematodes can weaken and sometimes kill plants. Thousands of nematode species infect nearly every staple and horticultural crop. The soybean cyst and root-knot nematodes are two of the worst culprits. The first attacks soybeans; the second, more the gourmand, feeds on strawberries, most vegetables and just about every other agricultural crop.

A story about the nematode studies appears in March’s Agricultural Research magazine. The story also is on the World Wide Web at:

http://www.ars.usda.gov/is/AR/archive/mar99/nema0399.htm

Scientific contact: David J. Chitwood, ARS Nematology Laboratory, Beltsville, Md., phone (301) 504-5660, fax (301) 504-5589, dchitwood@asrr.arsusda.gov.