Borer Thwarted by Its Appetite and a Fungus
November 10, 1997
A hungry European corn borer larva may meet its match if it crawls onto a
corn plant occupied by a common field fungus, Beauveria bassiana.
Scientists at the Agricultural Research
Service are using newfound knowledge of the harmonious relationship between
the plants and the fungus to develop the fungus as a new natural control.
Agronomists estimate corn borers cost growers millions of dollars annually and
may cause yield losses up to 30 percent.
Borer larvae burrow into cornstalks early in the season when corn plants are
only a few inches tall. The pests feed on the plants, sapping their energy and
nutrients. Feeding damage also contributes to lodging, or fallen stalks, when
the plants mature and dry in the fall.
The soil-dwelling fungus has long been known to be toxic to borers. But
scientists at ARS Corn
Insects and Crop Genetics Laboratory, Ames, Iowa, recently discovered that
the fungus and corn plants can coexist without harming each other. The fungus
lives and grows on the plant, and corn borer larvae that feed on the leaves
become fungus food. Fungus spores attach to a larva, germinate, penetrate it
and consume it.
C. Lewis and colleagues are conducting studies under a cooperative research
and development agreement with Mycogen
Seeds, St. Paul, Minn., and Mycotech Corp., Butte, Mont. In
field trials, researchers saw 53 percent less borer damage on fungus-treated
plants than on untreated controls. They applied Beauveria to leaves of
young corn plants at the time of first flight of the adult corn borer moth. The
moths seek mates during these flights, then lay their eggs on corn plants. But
when larvae hatch and feed on a fungus-treated cornstalk, they ingest the
fungus and die.
An article about the research appears in the November issue of
Research, ARS monthly magazine. The article is also on the
World Wide Web at:
Scientific contact: Leslie C. Lewis, USDA-ARS Corn Insects and Crop Genetics
Research Unit, Ames, IA 50011, phone (515) 294-8614, fax (515) 294-2265,