BEHOLD THE FUTURE of turfgrass pest management: an insect killer so tiny we can't even see it and an OARDC entomologist who's showing the industry just how effective biological control agents can be.

Parwinder Grewal has been successfully working with entomopathogenic (or insect-parasitic) nematodes to combat serious pests of turfgrass, especially white grubs — the root-feeding larvae of scarab beetles such as masked chafers, the Japanese beetle and the oriental beetle.

"Entomopathogenic nematodes are probably the best alternative to treat white grubs in the fall, when you can actually see the larvae," Grewal said. "Most chemical insecticides available today have to be used preventatively during the summer, and much of what's applied is lost. Besides, nematodes are easily mass-produced and applied using conventional spray equipment. They are safe for humans, animals and plants, and homeowners don't need a pesticide license to apply them."

Found abundantly in the soil, entomopathogenic nematodes (Steinerma and Heterorhabditis) are microscopic roundworms that parasitize and kill many insect and mollusk agricultural pests in the soil. They enter the body cavity of insects through natural openings and release bacteria that multiply and kill the host within three to four days. Several nematode species are used commercially for pest control in citrus, berries and mushroom crops, as well as in nurseries and greenhouses all over the world.

Grewal's research on nematode behavior and nematode-insect compatibility has been essential for the increasing credibility of nematodes as a biological control mechanism. This information has allowed him to determine which nematode species or strain is better suited to find and destroy white grubs, resulting in up to 90 percent white grub control according to recent trials.

Grewal has also discovered that some pesticides enhance the nematodes' parasitic effect when tank-mixed, creating an even more powerful killer. For instance, imidacloprid — one of the most widely used agents to destroy white grubs — disrupts the larva's normal nerve function and makes it easier for the nematodes to invade their host and start their parasitic cycle. This combination reduces costs and provides a safer and more environmentally friendly alternative to more hazardous agrochemicals used for turfgrass pest control.

The success of Grewal's research has not gone unnoticed by the lawn-care industry. In 2001, TruGreen ChemLawn — one of the country's largest lawn and landscape care companies, with research headquarters in Delaware, Ohio — teamed up with OARDC to study the feasibility of offering nematodes for white grub control to its customers.

"We have conducted trials in Wooster and Delaware, and the results are very promising," said Karen Novosel, a research scientist with TruGreen Technical Center. "Our partnership with Parwinder and Ohio State has been excellent."

Grewal and Novosel are also conducting nematode trials in New York state, in collaboration with Cornell University and the New York Department of Environmental Control.

"New York has been cracking down really hard on the use of chemical control for aesthetic purposes, such as lawn care," Novosel explained. "So far the results are great, and everyone there is very excited about the project."

For complete information about nematodes, call (330) 263-3963 or log on to http://www.oardc.ohio-state.edu/nematodes.

Nematode trials at TruGreen's facilities in Delaware, Ohio, have
shown very positive results.

Microscopic nematodes can be more effective than chemical insecticides when fighting turfgrass pests, especially white grubs. They are also clean, safe and environmentally friendly.

Parwinder Grewal sees a promising future for nematodes.

Nematodes can be applied using conventional spray equipment by both professionals and homeowners.

Scientist Karen Novosel, of TruGreen ChemLawn, is excited about the partnership between her company and OARDC. Intern Aaron Meyer assists her during a trial.