A New Defense Against Insect Pests

A bacterium called Chromobacterium suttsuga has been found to be effective against Colorado potato beetles, corn rootworms, diamondback moths, silverleaf whiteflies and green stinkbugs. These pests collectively cost farmers almost $3 billion annually in crop losses and control expenses.

The team of ARS scientists involved in the research includes microbiologist Phyllis Martin, laboratory technician Ashaki Shropshire, molecular biologist Dawn Gundersen-Rindal and entomologists Dale Gelman, Michael Blackburn and Robert Farrar--all at the Insect Biocontrol Laboratory in Beltsville, Md.--plus entomologist Jeffrey Aldrich and visiting scientist Edson Hirose at the Chemicals Affecting Insect Behavior Laboratory, also in Beltsville. A patent application for the discovery has been filed.

In lab tests, the scientists found that C. suttsuga seems to produce multiple toxins that deliver a lethal blow to the pests. Preliminary results from field tests have confirmed lab results, and more field tests are planned.

The bacterium's toxins can be combined with chemical compounds and then applied to soil, plants or seeds. To control soil-dwelling pests, rice grains can be treated with the toxins and applied to the soil, where pests will feed on the treated grains.

Insect pests often develop resistance to chemical insecticides, so biological compounds are regularly investigated for insecticidal properties. Biological control agents can be an important addition or alternative to synthetic chemical pesticides, and important in integrated pest management.

Other advantages of C. suttsuga are that it's stable in the environment, and insects readily ingest it.

The discovery may ultimately provide a new control for agriculturally important insect pests and give growers alternatives to chemical insecticides.

ARS is the chief scientific research agency of the U.S. Department of Agriculture.