Fungus Eyed as Stopper of Ash-Killing
Beetle By Luis
Pons April 13, 2007
Beauveria bassiana, a soilborne fungus already used for keeping
many insect pests in check, is being eyed as a possible control for an invasive
beetle that has already killed more than 20 million ash trees in Michigan,
Ohio, Indiana, and Ontario.
Agricultural Research Service (ARS) entomologist John
Vandenberg and colleagues want to know how well a commercial strain of
B. bassiana stands up to the emerald ash borer after repeated
applications. They are also seeing if this straincalled GHAwill
work better if used with the commercial insecticide imidacloprid.
B. bassiana spores kill insects by attaching to them,
germinating, and penetrating their hosts' bodies. The spores can survive to
infect later pest generations. B. bassiana is used against a variety of
insects, including termites and whiteflies.
The emerald ash borer is thought to have entered North America during
the 1990s in solid woodpacking material from Asia. Its immature larvae feed on
the vascular-system tissue of ash trees.
First spotted here in 2002 near Detroit, the destructive beetle has
since cost municipalities, property owners, nursery operators and forest
products industries tens of millions of dollars, according to the U.S. Forest
Service (USFS). Infestations were recently
found in the Chicago area.
According to Vandenberg, of the ARS Plant Protection Research Unit (PPRU),
Ithaca, N.Y., preliminary studies led by USFS scientist Leah Bauer have shown
that the beetle is susceptible to B. bassiana. However, the fungus'
effectiveness in larger field trials has not yet been proven.
At a commercial tree nursery near Jackson, Mich., Vandenberg, Bauer,
Griggs, Cornell University scientist
Louela Castrillo and Michigan State
University researcher Houping Liu are studying the performance of the
fungus on about 400 ash trees in three planting areas.
A possible strategy against the beetle would entail spraying the
fungus on trees before the pests' spring mating season, according to
ARS and the U.S. Forest Service are agencies within the
U.S. Department of Agriculture. ARS is
USDA's chief in-house scientific research agency.