Twenty honeybee queens imported from Russia's eastern Primorsky region could soon become matriarchs of a new generation of U.S. bees that resist varroa mites. ARS scientists imported the queens from Primorsky because heavy mite selection pressures there have forced the insects to develop natural defenses. In the United States, feral and managed bees lack sufficient natural resistance to the mite, which has become an invasive species here. Severe infestations of the blood-sucking parasite can destroy a hive unless checked with chemical miticides. But the cost of miticides, concerns over handling them, and the potential for mites to develop resistance have fueled the search for bees that can withstand the parasite on their own. Summer 2000 marks the third time ARS researchers have imported Russian queens as a source of mite resistance for domestic bees, which pollinate about $14.6 billion worth of crops. In spring 2001, ARS researchers will put the Russian queens and their American hybrid offspring to the test by infesting their hives with hundreds of varroa mites. Next, 40 daughter bees from the sturdiest hives will be shipped to commercial apiaries in Louisiana, Mississippi, and Iowa for further evaluation.

Honey Bee Breeding and Genetics Physiology Research Unit, Baton Rouge, LA
Thomas E. Rinderer, (225) 767-9280, trinderer@ars.usda.gov

Pecan growers will appreciate a new, strong-growing pecan variety that produces high-quality nuts and has natural resistance to scab disease. The new variety, Nacono, was developed by ARS and the Texas Agricultural Experiment Station. Nacono results from a cross between the Cheyenne and Sioux varieties both well-known to growers for their high-quality nuts and scab resistance. Nacono's natural scab resistance allows it to be grown in most southern U.S. pecan-producing states and in most other pecan-production areas of the world. Scab is a fungal disease that attacks both nuts and leaves. For disease control, some growers spray fungicides as many as 10 times a year. Many rural landowners in the Southwest and Southeast derive primary or supplemental income from growing pecan trees in orchards or woodland pastures. In 1999, U.S. pecan production was about 342 million pounds, with a value of nearly $448 million. Georgia, Texas, New Mexico, Arizona, and Louisiana are the top five pecan-producing states. Nacono will be available only to nurseries in February 2001. Nurseries could have trees to sell to the public in early 2003. Trees of this variety will be incorporated into the USDA-ARS National Plant Germplasm System. The database for the National Plant Germplasm System can be found on the World Wide Web at http://www.ars-grin.gov/npgs/. USDA's is the only national pecan breeding program in the world.

Crop Germplasm Research Unit, College Station, TX
Tommy E. Thompson, (409) 272-1402, tet@tamu.edu

ARS researchers have released a new soybean germplasm line, DT98-2448, that naturally resists velvetbean caterpillar (Anticarsia gemmatalis) and soybean looper (Pseudoplusia includens), two major soybean leaf-eating pests. The new line will give soybean breeders more options for developing insect-resistant, high-yielding soybean varieties. DT98-2448 was developed from parentage that includes crosses with DP3589, a commercial cultivar adapted to the clay soils of the lower Mississippi River Valley, and with germplasm originating from Japan. Velvetbean caterpillar moths fly into soybean field crops when the weather warms and lay up to three generations of larvae during the growing season. The caterpillars feed on plant leaves, and a heavy infestation can wipe out an entire field in a few days. Soybean looper caterpillars can also destroy an entire field during a heavy infestation. A single female can lay up to 640 eggs at a time. Soybean loopers are particularly hard to control with insecticides because they have begun to develop resistence. Soybean breeders and researchers may obtain germplasm for the new line from the ARS scientist listed below.

Southern Insect Management Research Unit, Stoneville, MS
Craig A. Abel, (662) 686-5248, cabel@ag.gov

Corn plants may one day receive a reprieve from European corn borer attacks with the release of a new maize germplasm line. ARS researchers in Stoneville, MS, and Ames, IA, developed GEMS-0001, which has superior resistance to leaf-eating borers. It naturally repels the pests from feeding on corn plants. The female borer lays her eggs on the corn plant's leaves. Larvae crawl between the leaf and stalk, feeding on leaf blades, leaf sheaths (the thick portion near the bottom of the leaf), and collars (outside of the stalk). They also bore into the stalks and feed on corn ears. Damage is estimated at between $192 and $400 million a year in the Corn Belt alone. Total damage throughout the United States is about $1 billion a year. Insecticides are difficult to use because there is a narrow window of opportunity to spray before the larvae bore into the plant. This new germplasm line, which originated from a tropical maize plant from Peru, not only has good stalk-feeding resistance, but also excellent yield potential. Breeders and researchers can obtain germplasm from the ARS scientist listed below.

Southern Insect Management Research Unit, Stoneville, MS
Craig A. Abel, (662) 686-5248, cabel@ag.gov

A newly identified class of compounds helps pea plants defend themselves against pea weevils, one of their most important insect enemies. A team of ARS, university, and industry scientists discovered the compound, "bruchins," which the weevils produce. The plant comes into contact with the bruchins when a weevil lays eggs on the pea pods. Within a few hours, the plant starts producing a tumor, or gall, at the egg-laying site. By the time the eggs hatch, a large gall or tumor has become a barrier to the larvae, so they can't burrow directly into the pod and feed on the peas inside. This is the first time scientists have found chemicals that induce an otherwise healthy plant to form a tumor to resist insect infestation. The team also found that pea plants must possess a certain gene in order to take advantage of the bruchins. In the 1990s, other researchers found that pea plants with a certain genetic sequence—named "Np"—formed calluses in response to weevil infestations. But this is the first time that scientists have identified specific chemicals involved in the process.

Horticultural Crops Research Unit, Corvallis, OR
Robert P. Doss, (541) 750-8773, dossr@bcc.orst.edu
Insect Chemical Ecology Laboratory, Beltsville, MD
James E. Oliver, (301) 504-8639, joliver@asrr.arsusda.gov

ARS researchers have developed a strategy for detecting new Asiatic citrus canker (ACC) infestations. This bacterial disease—which is primarily spread by wind-driven rain—causes brown blemishes on citrus leaves, twigs, and fruit, resulting in fruit drop and loss of yields and quality. More important, these effects lead to a loss of local, national, and international markets due to quarantines on the transport, sale, and export of fruit from affected areas. Florida produces 75 percent of U.S. citrus. Worldwide, the United States is second to Brazil in citrus fruit production. The new strategy being used in a statewide survey to detect ACC is the outgrowth of an 18-month epidemiological study. It showed that the previously used 125-foot zone around infected trees, within which all citrus trees were removed, was insufficient to contain ACC. The ARS study determined that a 1,900-foot zone-which has become the new regulation-is required to limit further spread of the disease. The study also recommended that a 15-mile-wide by 20-mile-long "sentinel tree" grid composed of 144 existing residential trees of susceptible cultivars be established to detect and prevent the further spread of ACC. These findings have helped increase the ACC eradication budget to $175 million, with an additional $40 million for payments to growers hit by the disease.

U.S. Horticultural Research Laboratory, Ft. Pierce, FL
Tim R. Gottwald, (407) 897-7347, tgottwald@ushrl.ars.usda.gov