Wheat Stem Sawfly Attractants
By Ben Hardin
July 12, 2001
Hiding as if in a Trojan
horse, wheat stem sawfly larvae chewing inside wheat stems sometimes pose
problems for farmers in the Northern Great Plains. When technology is developed
to predict the danger, farmers will find it easier to decide whether pest
control treatments may be warranted.
As a first step, Agricultural Research
Service scientists at the National
Center for Agricultural Utilization Research, Peoria, Ill., have discovered
and synthesized some of the natural odors that attract adult sawflies of one
gender to another. Whether or not such odors may one day be used in trap baits
to monitor sawfly populations, the discoveries may lead to more novel
approaches to limiting sawfly damage.
The scientists focus their research on adult sawflies because once the
sawfly eggs are laid and the larvae are feeding safely within wheat stems,
insecticide spraying has little effect.
One of the sawflys own antennae, suspended between tiny electrodes,
provides a main platform for the research that makes use of a technique called
coupled gas chromatographic-electroantennographic detection (GC-EAD). In
response to odors, the antenna sends out electrical signals to help the
scientists pinpoint exactly the few chemicals that are critically important to
the sawflys behavior. The information helps researchers identify and
formulate various mixes of volatile chemicals to research the insects
behavior in a laboratory wind-tunnel or in the field.
In other research, the Peoria scientists are using GC-EAD to discover
attractants for sap beetles that are pests of figs, dates, and corn; other sap
beetles that spread a fungus that infects trees, causing oak wilt; exotic leaf
beetles that may someday control weedy tamarisk trees along western U.S.
streams; exotic flea beetles that now are being used as biological control
agents against leafy spurge; and flea beetles that are pests of canola and
other crucifer crops.
An article about the research appears in the July issue of ARS' Agricultural Research magazine.
ARS is the U.S. Department of
Agricultures chief scientific research agency.