Beetles Learn
that "You Are What You Eat"
By Sharon
Durham
March 12, 2004 Agricultural Research Service
scientists studying the Colorado potato beetle (CPB) with the goal of finding
an effective biological control against the pest have been hampered by the
insect's reluctance to eat a formulated diet. Now
ARS scientists in Beltsville, Md., have
developed a freeze-dried diet palatable to CPB.
Previously, the agency's Insect
Biocontrol Laboratory in Beltsville had developed a palatable diet for the
destructive beetle, but the diet had to be prepared immediately before feeding
or the picky insect pest wouldn't eat it.
To get around the problem, microbiologist Phyllis Martin and her colleagues
employed freeze-drying--commonly used to make instant coffee and packaged food
for astronauts--to preserve the diet after preparation. Martin found the
beetles readily eat a freeze-dried diet that has been moistened with water or a
suspension of bacteria. The freeze-dried diet is convenient because it allows
for long-term storage, estimated to be at least nine months.
The freeze-dried diet also has other benefits. Some toxins being considered
for control of CPB are heat-sensitive, which eliminated them from testing with
the previously formulated ARS diet that had to be prepared with boiling water.
Controlling CPB is vitally important to commercial growers. Both immature
and adult beetles feed on potato, eggplant and tomato vegetation, and have
developed resistance to most available insecticides. Researchers are looking
for alternative methods, such as bacteria or fungi that only harm target pest
insects such as CPB.
The freeze-dried diet seems to allow concentrated ingestion of the bacteria
meant to control CPB and will provide the means for testing a wider range of
bacterial and fungal controls.
More
information about the research is in the March issue of Agricultural
Research magazine.
ARS is the U.S. Department of Agriculture's chief scientific research
agency.
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