
Virus To Wage Hormonal Sabotage on Corn EarwormsBy Jan Suszkiw March
12, 1998With high-tech help, a natural insect virus could deprive corn earworms of
their greatest pleasure: feasting on corn plants at farmers' expense. The virus--called a baculovirus--infects corn earworms to multiply and
spread. But it is slow to kill, and may not adequately protect the plants. Now
a more potent form of the virus has been developed by
Agricultural Research Service scientist
Ashok Raina. Using biotechnology, he equipped the virus with new genes for
making a natural hormone to stem the corn earworm's appetite. Raina discovered the hormone, helicokinin-II (Hez-HK-II), in earlier studies
of the corn earworm's nervous system. He then cloned the Hez-HK-II gene and
inserted it into the virus. Normally, the hormone helps regulate the insect's growth from caterpillar to
adult moth. But Raina showed that infecting the pest with the modified virus
leads to hormonal sabotage. That's because the virus makes a surplus of
Hez-HK-II after invading the worm's gut cells. This overload stops the pest from feeding--a potential boon for the corn
plant's leaves, silk, tassel and other parts. In the South, the pest costs
farmers nearly $2 billion annually in losses and chemical control expenses. The baculovirus is an appealing alternative: It kills the pest from within,
eventually degrades outside its host and doesn't harm humans, animals, plants or
beneficial insects. In lab studies, hatchling worms infected with the modified
virus typically stopped eating after 48 hours. By 20 days, only 3 percent
survived and pupated compared with 100 percent for virus-free worms. The true test will come with field studies against wild corn earworms, which
are expected to be more robust than lab-reared specimens used thus far. Raina is
now collaborating with a commercial company to explore the virus' potential as a
biopesticide. A more detailed story appears in the March issue of ARS' monthly magazine,Agricultural
Research. The story is also on the World Wide Web at: http://www.ars.usda.gov/is/AR/archive/mar98/corn0398.htm Scientific contact: Ashok Raina,
Insect Biocontrol Laboratory,
Beltsville, MD 20705, phone (301) 504-9296, fax (301) 504-8190, [email protected]. Story contacts Insect Biocontrol Laboratory Ashok K Raina Jan R Suszkiw U.S. Department of Agriculture | |