Decisions on whether to apply insecticides to peach, apricot and other crops might be made easier by keeping tabs on the weather and monitoring sap beetle populations using traps containing synthetic versions of natural chemical attractants. By cutting out unnecessary chemical use, growers could help preserve the environment as well as their profit margin. The attractants first synthesized and patented by scientists of USDA's Agricultural Research Service were used by entomologists of ARS and New South Wales Agriculture in a five-year study in Australia. Sap beetles are found throughout the world and spread fruit-degrading fungi in a wide variety of crops. ARS scientists and colleagues around the world are studying ways to use attractants for environmentally friendly control of sap beetles in stored cacao and a wide variety of crops including figs, plums, pineapples and corn. One insect species trapped in the study was the confused sap beetle, Carpophilus mutilatus, also found in the United States. This species is believed to normally destroy about 10 percent of deglet noor dates in California and sometimes much larger portions of the bigger and more expensive medjool dates. The Australian researchers found minimal insect damage to stone fruit crops in years when lower-than-normal midsummer rainfall caused beetle populations to plummet and remain low until harvest. ARS is seeking more cooperators to speed development of sap beetle attractants in the United States.
National Center for Agricultural Utilization Research, Peoria, IL
Robert J. Bartelt, (309)681-6237, bartelrj@ncaur1.ncaur.gov

Benign strains of harmful fungi that cause wilt disease in tomato crops are being explored as natural replacements for methyl bromide. Methyl bromide has many pesticidal uses, including as a soil fumigant. But it is scheduled to be banned in 2001 because it has been identified as contributing to depletion of Earth's ozone layer. Wilt is caused by virulent races of Fusarium oxysporum fungi. These fungi attack tomatoes, cantaloupe, watermelon and many other crops. But ARS scientists have unearthed new strains of Fusarium that actually protect tomato plants from their disease-causing brethren. The beneficial strains induce plants to make natural chemical defenses. The chemicals kill or block virulent, disease-causing Fusarium fungi that try to infect the plants' water- and nutrient-carrying tubes. The good fungi aren't harmed because they reside solely on the roots. In greenhouse studies, up to 80 percent of tomato seedlings whose roots harbored the helpful microbes escaped the disease. Scientists began outdoor studies this spring on naturally infected tomato fields in Maryland. University researchers may also run tests in Florida. There, use of methyl bromide to protect tomato crops costs growers about $220 per acre.
Biocontrol of Plant Diseases Laboratory, Beltsville, MD
Bob Larkin/Deborah Fravel, (301) 504-5682

Mass production of a fungus that kills silverleaf whiteflies has doubled in efficiency in the past two years, thanks to improvements in the ARS-patented production technique. ARS scientists mixed Paecilomyces fumosoroseus spores with cornstarch, flour and sucrose before freeze-drying them. More than 80 percent of the spores were still viable after 5 months in storage. Now scientists at the Universidad Autonoma de Nuevo Leon, Monterrey, Mexico, are working with the ARS researchers to cut costs on the deep-tank fermentation of the fungal spores. Also under way: pinpointing the precise packaging and storage conditions needed to ensure the microbes will spring vigorously from their Rip Van Winkle state when mixed with water and sprayed on insect pests. The silverleaf whitefly, also known as strain B of the sweetpotato whitefly, is a pest of more than 300 plants worldwide. Since its discovery in this country in 1986, the tiny, sap-sucking insect has inflicted billions of dollars in damages on crops in Arizona, California, Texas and Florida. (PATENT APPLICATION 08/623,915)
National Center for Agricultural Utilization Research, Peoria, IL
Mark Jackson, (309) 681-6283, jacksoma@ncaur1.ncaur.gov

At Zephyr Egg near Tampa, Florida, you can walk into a poultry house and hardly see a house fly. That's because ARS scientists and University of Florida cooperators released a predatory fly-- the black dump fly--that gobbles up house fly larvae that live in poultry manure. Each week for a year, the scientists released 70,000 black dump flies into the poultry houses at Zephyr. The company is one of the largest egg producers in Florida, with two million chickens that can produce up to 300 tons of wet manure a day. This is heaven for house flies that breed in the manure. But a single dump fly larva can kill up to 20 house fly larvae a day. Soon after releasing the dump flies, the house flies had virtually disappeared. This meant Zephyr no longer had to spray an estimated $12,000 a year in chemical pesticides to control the pests. And organic farmers are now interested in buying the chemical-free manure. The black dump fly, native to the United States, will kill more house fly larvae than it can eat, making it an excellent biocontrol insect. Another plus: Dump flies won't bother people. Black dump fly larvae will also eat the larvae of stable flies and other pests. Black dump flies are sold commercially in the United States, Canada and Europe, and have been used predominantly in the midwestern United States. But this is the first time the flies have been used as far south as Florida to control house flies in a commercial poultry house. ARS scientists are now working with a Florida poultry farm that wants to breed the flies in an on-the-farm insectary. The scientists also are also testing the dump flies for controlling pest flies in manure at dairy farms.
Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL
Jerry Hogsette, (352) 374-5912

A tiny wasp might help California cotton growers thwart cotton aphids. Last fall, ARS researchers and colleagues at California's Department of Food and Agriculture placed 1,700 wasps--known as Aphelinus near paramali--on cotton plants in a San Joaquin Valley field. The scientists now are checking to see if the insects survived to produce offspring. The female wasp pumps an egg into an aphid using her ovipositor, a tube-like appendage. The egg hatches into worm-like larva that feeds on the pest's innards, killing it. Sometimes, instead of laying an egg, the female wasp sips fluids that ooze from the wound made by her ovipositor. The cotton aphid, also known as melon aphid, secretes a sticky honeydew that contaminates cotton fibers. Sticky fibers can jam cotton gins or spinning equipment in textile mills, reducing the crop's value to growers. Besides cotton, this aphid threatens citrus and cucurbits such as cantaloupe, watermelon and squash by transmitting plant viruses. Among the viruses: citrus tristeza, watermelon mosaic virus and zucchini yellows mosaic virus. Wasps recruited for the California experiments are native to Florida. They were originally reared at an ARS lab in Orlando. The Orlando scientists were the first to recognize the wasp's potential as a natural enemy of cotton aphids and green peach aphids. They also were the first to lab-rear the wasp for greenhouse and field tests.
Western Integrated Cropping Systems Research Unit, Shafter, CA
John McLaughlin (805) 746-8001, jmclaughlin@lightspeed.net

Tiny Italian fleas arrived in the United States this spring to start eating musk thistle. This spine-covered weed invaded from Europe 150 years ago. Today it infests millions of acres of pasture, range and other areas in 32 states. Musk thistle grows to 6 feet tall and chokes out forage and other desirable plants. Because of its spines, cattle won't graze near musk thistle, and the spines pose a prickly hazard for hikers. Herbicides are often too costly and can't be used near parks and similar areas. Scientists believe the best long-term strategy is to import the weed's natural enemies from "the old country" and develop thriving populations of musk-thistle eaters. The Psylliodes chalcomera flea beetles are the latest of four insects ARS and cooperating scientists imported to fight the weed. Adult flea beetles feed on the weed's rosette, or crown, and larvae feed on leaves and buds. Scientists first released the insects in Texas in March and Kansas in April. Next year, ARS scientists will supply flea beetles for releases in 20 other states. Before applying for USDA permits to import and release the insects, ARS scientists ran tests in Italy to determine that they have no appetite for important U.S. plant relatives of musk thistle, such as artichoke, chicory and native thistles.
Grassland, Soil and Water Laboratory, Temple TX
Paul Boldt, (817) 770-6530, boldt@brcsun0.tamu.edu
European Biological Control Lab, Montpellier, France
Gaetano Campobasso, 011-39-620-609-346, ebcl.RomeSubstation@agora.stm.it

Last Updated: April 25, 1997
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