Key Insect Pest Could Go Hungry on New
By Jan Suszkiw
August 15, 1997
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 USDAs
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 isnt the rootworms 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 seeds
housing--to the rest of the plant. By eating the pegs, rootworms cut the seed
off from vital nutrients so they cant 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
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,
Pittman, ARS Plant Genetic
Resources Conservation, Griffin, Ga., telephone (770) 229-3252, fax (770)
229-3323, e-mail firstname.lastname@example.org.