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Lab Diets for Two Pest Insects


  The Y2K bugs at ARS' Insect Biocontrol Laboratory in Beltsville, Maryland, aren't of the computer kind. Rather, they're two crop-attacking insects: the Colorado potato beetle and the silverleaf whitefly.


Both are the focus of separate, though related, projects of entomologists Dale B. Gelman, Robert A. Bell (now retired), Jing S. Hu, and Michael B. Blackburn. As part of their research, these scientists are creating artificial diets to sustain lab colonies of the insect pests so new weaponry can be more easily tested against them.


Furthest along is work against the beetle, whose larvae cost tomato, potato, and eggplant growers over $150 million annually in losses and insecticide expenses.


The pesticide Admire is a standard defense, but experts fear the beetle may soon develop resistance to it. That's why the Beltsville team is looking for ways to streamline research aimed at finding insecticide replacements—or biological alternatives like parasiticEdovum puttleri wasps.


Until now, rearing lab colonies of beetles meant feeding them on a living host, such as potato plants. But growing the plants is expensive and time-consuming.


So Gelman's lab developed a relatively simple artificial diet using oats, lettuce, potato leaf powder, and other ingredients. Dried into powder, lettuce replaces most of the potato leaf material normally required. In addition to cutting costs, "lettuce is easier to obtain because you can buy it at the grocery store," Gelman says.


More importantly, it stimulates most beetles to eat the diet. Gelman's lab has reared nine beetle generations on it so far. After analyzing each generation's average weight, growth, egg production, and other data, the scientists plan to publish their findings.


Indications are "the diet will prove useful for growing beetles in the lab for research purposes," says Gelman. "And you can rear them on it year-round in a cost-effective manner."


Gelman, Hu, and Blackburn are also artificially rearing silverleaf whiteflies to better understand the growth requirements of wasps likeEncarsia formosa that parasitize the pests.


They hope that by learning to rear the whiteflies, an artificial wasp diet can be created. However, "this project is still in its infancy," Gelman says. "Right now, we're just dissecting the parasites out of the whiteflies and seeing how they develop."—By Jan Suszkiw, Agricultural Research Service Information Staff.


Dale B. Gelman, Michael B. Blackburn, and Jing S. Hu are at USDA-ARS Insect Biocontrol Laboratory, Bldg. 003, 10300 Baltimore Ave., Beltsville, MD 20705-2350; phone (301) 504-8909, fax (301) 504-8190.

"Lab Diets for Two Pest Insects" was published in the April 2000 issue of Agricultural Research magazine.




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