A new, resistant peanut breeding line could mean trouble for hungry southern corn rootworms and good news for the peanut growers who must apply soil insecticides to fight them.

Scientists with USDA’s Agricultural Research Service and the Virginia Agricultural Experiment Station in Suffolk developed, tested and evaluated the new Virginia-type peanut called VGP11. The ARS germplasm repository in Griffin, Ga., maintains a limited supply of the seed for breeding new commercial cultivars.

Corn isn’t the rootworm’s sole cuisine. The soil-dwelling pest also hungers for the “pegs” and “pods” of peanut plants. Pegs are umbilical-like stems that link the pod--a young peanut seed’s housing--to the rest of the plant. By eating the pegs, rootworms cut the seed off from vital nutrients so they can’t mature and be harvested. But VGP11 peanut plants have genes that make their pegs unappealing--or even deadly--to rootworms. Scientists suspect a natural chemical defense is at work.

In lab studies, up to 89 percent of rootworm larvae died after being fed a diet of peg tissue from VGP11 plants. Similar results were seen in field trials, resulting in peanut yields higher than NC 6, an older resistant variety grown in Virginia and North Carolina. Together, the states produce 18 percent of all U.S. peanuts.

Unchecked, rootworm feeding can cause pod losses of up to 40 percent. But commercial cultivars bred from the new peanut line could better withstand the pest, cutting growers’ need for chemicals such as chlorpyrifos to do the job.

VGP11 plants produce large pods with high-quality kernels and oil content. The thin pink skin that envelops them also comes off more easily than that of NC 6, a boon during processing.

Scientific contact: Terry Coffelt, ARS U.S. Water Conservation Laboratory, Phoenix, Ariz., telephone (602) 379-4356, fax (602) 379-4355, [email protected]; Roy Pittman, ARS Plant Genetic Resources Conservation, Griffin, Ga., telephone (770) 229-3252, fax (770) 229-3323, e-mail [email protected].