A tiny parasitic wasp from Europe is a promising natural control for the tarnished plant bug, a major pest of strawberries in the eastern three-quarters of the United States. In New England, the bug causes average annual losses of $300 per acre to strawberries. Chemical insecticides are growers' only sure remedy. But as a result, the bug has nearly eliminated organic farmers from growing the crop, since they can't use chemical insecticides. An ARS scientist imported the Peristenus digoneutis wasp about two decades ago. When a female Peristenus stings a young plant bug nymph, she lays a tiny egg in it. A few days later, a wasp larva hatches and begins to eat the nymph, killing it in about a week. The parasite was first released experimentally in northern New Jersey in alfalfa—a widely grown crop that is a plant-bug favorite. The wasp soon reduced the pest's numbers in alfalfa fields by 75 percent. It has gradually spread into six other northeastern states—New York, Rhode Island, Massachusetts, Connecticut, Maine, Vermont and New Hampshire. The next goal was to determine if the parasite would fly from alfalfa to nearby strawberry fields and attack the bug there. In 1998, ARS and state cooperators in New York and New Hampshire confirmed that it would. They found that the wasp was present in most strawberry fields they checked and it was parasitizing up to 55 percent of the tarnished plant bugs. Future research will determine if the wasp can kill enough tarnished plant bugs to reduce the bug's strawberry damage to minor levels. That would lower and possibly eliminate the need for insecticides, as well as reduce production costs.
Beneficial Insects Research Laboratory, Newark, DE
William H. Day, (302) 731-7330, ext. 24.

Gypsy moth caterpillars seeking refuge beneath burlap skirts placed on tree trunks could be in for a fatal surprise. Applying a latex coating of chloryrifos insecticide beneath the skirts can kill more than 60 percent of caterpillars hiding there. The skirts are a property owner's first-line defense against the leaf-eating insects, a costly menace to millions of acres of forest and shade trees, primarily in the Northeast and Mid-Atlantic areas. The skirts exploit the tendency of caterpillars on the ground to hide during the day and emerge at dusk to feed high in the tree canopy. Property owners must check under the skirts before dusk and destroy any caterpillars they find. Dropping the pests in a bucket of soapy water or bleach does the trick. But on large properties, this can become tedious. To save time, and ensure fewer caterpillars escape detection, scientists apply the insecticidal latex coat directly onto the bark beneath the skirts. In one 31-day field test, they observed that a single 6-hour exposure period killed 64 percent of caterpillars hiding there. On uncoated tree trunks with the skirts, 95 percent survived. Scientists hope to replicate the results this spring. Eventually, they may try using a biopesticide product containing spores of natural, caterpillar-killing fungi.
Insect Biocontrol Laboratory, Beltsville, MD
Geoffrey White, (301) 504-5689.

New high-tech capsules offer a better way to feed beneficial insects and to control pests. ARS scientists are working with researchers at Analytical Research Systems, Inc., Gainesville, FL, to develop low-cost, biodegradable capsules that could be used as food supplements in the field to maintain beneficial insect populations when there's a shortage of prey. The capsules might also be filled with microbial pest control agents such as protozoa, bacteria and viruses. Food-filled capsules could also be used instead of natural prey to reduce the costs of mass rearing insect predators for biological control use. ARS tests with fire ants showed that foraging workers readily take the capsules into their nests, open the package and devour the contents. The capsules, 2 to 5 mm in diameter, hold aqueous and/or oily materials—a key advantage over other capsules that are designed to dissolve in water. A grant from USDA's Small Business Innovation Research Program and a cooperative research and development agreement are supporting this research.
Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL
Patrick D. Greany/David F. Williams, (352) 374-5763/5982.

A triple whammy of chemicals, lime and parasitic wasps could bring relief to people and farm animals plagued by nuisance houseflies. Pesticides alone aren't enough to control houseflies, because the pests have developed resistance to cyromazine. This popular growth regulator, added to chicken feed, passes through the bird and kills fly larvae in the manure. ARS researchers and scientists from the Institute of Agricultural Microbiology and Zoology in Buenos Aires, Argentina, conducted field tests in commercial poultry houses with cyromazine-resistant houseflies to find the most effective control. They found the best system for reducing housefly populations included limited use of topically applied cyromazine—at higher concentrations than the feed additive—along with chemical pesticides, cultural control such as lime, and two parasitic wasps, Spalangia endius and Muscidifurax raptor. These wasps are found worldwide, including the United States, and do not bite or sting people or animals. The wasps were released at a rate of five of each species per hen per week after pesticide applications were stopped. Combining these control practices reduced flies by 98 percent and resulted in a 3.5 percent cost savings compared to chemical treatments alone. Combined treatments also resulted in a 2 to 3 percent labor savings.
Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL
Jerome A. Hogsette, (352) 374-5912.