
Hairy Vetch Thwarts Colorado
Potato BeetleBy Sharon Durham April 13, 2000Colorado potato beetles are
deceptively beautiful insects, with five shiny black stripes on a yellow
background decorating each wing. But this beetle is notorious for its
destructive power. Each year, the Colorado potato beetle and its larvae ravage
potato, eggplant and tomato plants. This pest is also notorious for something else: its ability to develop
resistance to insecticides. Because of this, biocontrol becomes a viable
option. Biocontrol--the use of one natural organism to control another without
chemicals--has an important place in farming systems, including organic
farming. Agricultural Research Serviceentomologist Kevin Thorpe and collaborators at the
University of Maryland have found that an
organic mulch made from a cover crop called hairy vetch can reduce Colorado
potato beetle damage. They utilized the method developed by ARS plant
physiologists Aref Abdul-Baki and John Teasdale, in which hairy vetch is
planted in the fall and mowed in the spring before transplanting. The vetch
impeded the movement of the beetles, thereby lessening their damage. The vetch,
a legume, also added nitrogen to the soil. In the study, fewer beetles infested tomatoes transplanted into hairy vetch
mulch, compared to tomatoes transplanted into black plastic mulch. Yields of
staked, fresh-market tomatoes grown in the vetch mulch were comparable to
tomatoes treated with insecticides. The Colorado potato beetle costs U.S. potato, tomato and eggplant growers
about $150 million annually in losses and insecticide-related costs. Many
growers are using imadacloprid, a new systemic insecticide that provides
excellent control. However, unless appropriate measures are taken, resistance
will develop. Non-insecticidal methods of control could be useful components of
a sustainable, integrated pest management strategy if they can reduce pesticide
inputs and slow the rate of resistance. Thorpes next step is investigating the use of organic mulches in
larger fields of staked fresh-market tomatoes grown on a commercial scale. This
study was undertaken as part of the Sustainable Agriculture program at the
Beltsville (Md.) Agricultural Research
Center. Scientific contact: Kevin Thorpe,
ARS Insect Biocontrol
Laboratory, Beltsville, Md., phone (301) 504-5139, fax (301) 504-5689,
[email protected]. Story contacts Donald R Barnard Sean T Adams U.S. Department of Agriculture |