Last Meal for Colorado Potato Beetle?

A last meal could be in store for Colorado potato beetles in the form of a new artificial diet cooked up by Agricultural Research Service entomologists in Beltsville, Md.

But "chef" Dale Gelman and ARS colleagues there aren't trying to poison the pesky beetles with their new diet. Rather, the scientists are working to step up the pace of entomological research aimed at testing new weaponry that farmers eventually can use against the beetles. The pest's larvae devour the leaves of eggplant, tomato and potato plants, causing $150 million annually in crop losses and chemical control expenses.

The chemical pesticide Admire is a standard defense, but experts fear the beetle may soon develop resistance to it. That's why Gelman's team at ARS' Insect Biocontrol Laboratory in Beltsville is trying to streamline research aimed at finding alternatives, particularly biological ones like the parasitic wasp Edovum puttleri. Female wasps hatch their larvae inside the beetle's eggs, destroying them.

Until now, rearing lab colonies of the beetles meant feeding them on a living host--namely potato plants. But growing them is costly and time-consuming. So, scientists developed a simple artificial diet made of oats, lettuce, some potato leaf powder and other ingredients. Dried into powder, lettuce is cheaper, easier to obtain than potato material and--most important--whets the beetle's appetite.

So far, Gelman's team has reared nine generations of beetles on the diet. Once perfected to the beetle's taste, the team will transfer the diet technology to a commercial producer for researchers to use in lab studies.

An article on the work appears in this month's issue of Agricultural Research magazine and on the web.

ARS is the U.S. Department of Agriculture's chief scientific arm.

Scientific contact: Dale Gelman, ARS Insect Biocontrol Laboratory, Beltsville, Md., phone (301) 504-8909, fax (301) 504-8190. dgelman@asrr.arsusda.gov.