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A natural fungus could be a new weapon against insects that infest
stored grain. Beauveria bassiana had a success rate
of 80 to 100 percent in killing invading insects in preliminary lab tests.
ARS scientists are investigating it as a biocontrol against rice weevils,
lesser grain borers and red flour beetles. These insects--primarily
during their immature, wormlike stage--can ruin stored rice, corn, wheat
and sorghum. Currently, chemical insecticides are growers' main recourse,
but some registrations are scheduled to be withdrawn. ARS scientists
envision Beauveria as a potential alternative. In their
experiments, the fungus killed the adult insects within two to four weeks
after infecting them. But the fungus doesn't grow on the stored grain and
is harmless to humans and animals. For tests, scientists incorporated the
fungus into a powder. They then mixed the powder with brown and
long-grain rice in containers simulating storage bins. Next they released
adult insects into the containers for up to 21 days. Results: the insect
kill-rate of 80 to 100 percent. Scientists caution further research is
needed, particularly to find how it can be formulated. Ideally, Beauveria
could be deployed to squelch the first infestation of adult insects. This
would greatly reduce numbers of a succeeding generation of wormlike
offspring.
Rice Research Unit, Beaumont, TX
Robert Cogburn/ William
Rice, (409) 260-9343/(318) 788-7553
A natural fungus could even the odds against common cocklebur, a tall,
bushy weed that bullies smaller soybean plants in competing for sunlight
and nutrients. Many herbicides don't control cocklebur infestations,
which can cause soybean yield losses of up to 80 percent. ARS scientists
hope to curb its destruction with the fungus Alternaria
helianthi. They discovered, in greenhouse studies, that the
fungus causes a blight disease that killed over 90 percent of cocklebur
seedlings in seven days. Researchers have since tested the fungus against
12 different strains of the weed. They plan field studies and are testing
a water-corn oil formula that helps the fungus more easily infect the weed
and bolsters its killing power. Success of the experiments could
encourage agri-chemical companies to formulate it as a "bioherbicide" for
protecting soybean, cotton and other crops.
Southern Weed
Science Laboratory, Stoneville, MS
Hamed K. Abbas, (601) 686-5313
Last updated: October 22, 1996
Return to: Quarterly Report
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Last Modified: 02/11/2002
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