Scientists Plot Genetic Ploy Against Grain Pest
By Jan Suszkiw
November 2, 2009
Aided by a genomic map of the red
flour beetle, Tribolium castaneum, Agricultural Research Service (ARS) and
university scientists are plotting a kind of genetic sabotage on the
pests basic life functionsfrom locomotion to digestion.
Nationally, infestations of flour beetles and their beetle cousins cost
millions of dollars in losses annually to stored grains and the food products
made from those grains. Warehouse sanitation usually keeps beetle numbers down,
but severe cases can necessitate the use of chemical controls. The problem is
that T. castaneum has shown a propensity for developing resistance to
As an alternative, a team of ARS and Kansas
State University scientists is examining ways to exploit specific genes
that regulate where, when and how a substance called chitin is used to form the
beetles outer shell, or exoskeleton.
Led by ARS entomologist
Beeman, the team identified nine genes encoding specialized enzymes, dubbed
chitin deacetylases (CDAs), which trim off branches of a long chain
of simple sugars that make up raw chitin.
Which branches get trimmed depends on where chitin is needed on a developing
beetles body, and for what purpose, explains Beeman, with the
Stored Product Insect Research Unit in Manhattan, Kan. For example, around
leg joints, chitins branched-chain structure must be snipped to allow for
flexibility and movement. But around the head and thorax, where protection of
vital organs is key, a heavier, stiffer chitin deposition is needed, requiring
a different form of CDA trimming.
Beeman and KSU collaborators Subbaratnam Muthukrishnan and Yasuyuki Arakane
used a biotech procedure called RNA interference to demarcate the
genes roles and observe what effect their elimination had on the
insects development or survival. Some CDA-deficient strains developed in
the lab couldnt bend their legs as adult beetles, making it impossible
for them to walk, mate or feed. Another such strain couldnt shed its old
Ultimately, such observations could open the door to chitin-disabling
biopesticides or anti-chitin proteins engineered into crop plants.
more about this research in the November/December 2009 issue of
Agricultural Research magazine.
The research supports the U.S. Department of
Agriculture priority of promoting international food security.
ARS is USDAs principal intramural scientific research agency.