PHOTO COURTESY: SYNGENTA PROFESSIONAL PRODUCTS

There's no question synthetic insecticides are more pest specific than ones used 20 years ago. Golf course superintendents can use less of a product, still have improved effectiveness and not worry as much about off-target issues.

"Over my 30-year career as a superintendent, the progress that's been made is significant, considering the highly toxic products used in the early 1980s," says Scott Werner, superintendent at Lincolnshire Fields Country Club, a private, 18-hole course in Champaign, Ill.

But to place all new insecticides into a "more environmentally friendly" category isn't so simple.

"You can't lump all insecticides, no matter how new they are, together," says Dave Shetlar, Ph.D., associate professor in the department of entomology at the Ohio State University. "Just saying they're less toxic and that we use less of them is an oversimplification. The way these insecticides work makes all the difference in the world as far as safety is concerned."

Insecticides are rated with an LD50 number to indicate their toxicity levels. LD50 is the abbreviation for the amount of toxicant needed to kill 50 percent of a test animal population. It's expressed in terms of weight of chemical per unit of body weight. LD50 is also used to measure the acute oral and dermal toxicity of a chemical — the lower the LD50 value, the more poisonous the chemical. LD50 isn't a measure of environmental hazard.

A low acute toxicity rating isn't the same as environmentally friendly, Shetlar says. For example, fipronil has an LD50 of just 97. "It's extremely toxic, but it's used at very low rates," he adds. "At those low rates, it has a minimal impact on nontargets. It's commonly used for fire ants, mole crickets, and for fleas and ticks on dogs and cats."

Dursban and diazinon were used "everywhere against everything," Shetlar adds. "That's why the EPA banned them."

And then there's DuPont Professional Products' Acelepryn (chlorantraniliprole), which is in a category all by itself because its LD50 number is higher than 5,000, Shetlar says.

"And if the LD50 number is that high, the EPA says you don't need a signal word on the label," he says. "It's the first product I know of that has no caution label."

Shetlar says Valent's Arena has an active ingredient (clothianidin) with an LD50 of 5,000. "But the inerts made it more toxic," he adds. "The LD50 of that product is 3,500. With an LD50 of less than 5,000, you need a caution label."

One measure of safety for an insecticide is its effect on nontargeted pests. The newer chemistries are picking up on neural differences in insects and animals, making them more targeted, hence less toxic to noninsects, Shetlar says. But to go to the next level of safety is not an easy task.