“Beneficial insects work 24 hours a day, seven days a week, and they don’t need a green card,” says Clemson University Entomologist Powell Smith.

Speaking at the recent Carolina Fruit and Vegetable Growers Expo, Smith says using what he calls ‘soft’ insecticides can provide good insect control and spare beneficial insects that can create an overall excellent insect management program in vegetable crops in the Southeast.

Beneficial insects fit into IPM (integrated pest management) programs nicely and they can help significantly with insect management. In some situations growers can get comparable insect control from a soft insecticide plus beneficials versus using a broad spectrum insecticide that kills the good and the bad insects in a field, Smith contends.

“In 2011, cabbage loopers were plentiful. Typically if we found 1 or 2 diamondback moths, we would find 8-10 loopers — it is the most unusual insect year I’ve seen in over 35 years of working with vegetable crops,” Smith says.

In tests conducted in commercial fields across South Carolina, Smith says a number of biological, or soft insecticides were used to control both diamondback moths and cabbage loopers.

The most prominent of these materials is Dipel.

Other materials include Radiant, which is similar to Spintor, which is used extensively on vegetable crops in the Southeast, as are Proclaim, Avaunt, Coragen, and Vetica. With the exception of Vetica and Coragen, all these materials come from different chemical classifications.

Having different modes of action is critical to develop a rotation program for insecticides and help reduce the risk of developing insecticide resistance. Smith says companies that sell these products have done a good job of educating growers to the active ingredient in each product.

One cabbage looper eats as much as five diamondback moths, so Smith used a threshold of one cabbage looper per 10 plants or five diamondbacks per 10 plants. Once we got to this threshold, we sprayed one of the soft insecticides, he says.

“Vegetables were planted the first week in June and by the end of the month, we had enough caterpillars to spray,” Smith says. “Each material, combined with beneficials, did a good job of protecting the crop against damage from cabbage loopers and diamond back moths.”

With Dipel, they sprayed fields an average of three times to prevent buildup to threshold levels. “With Proclaim we needed four sprays, Radiant and Coragen required three sprays. Avaunt and Vetica thresholds were reached only twice.