For more details, see: Agricultural Research.

Three Wasps from Mexico May Curb New Alien Scale Pest

An insect collected from a hibiscus plant in Bradenton, Fla., in July 1998 heads the list of new invasive alien insect pests.

Agricultural Research Serviceentomologist Douglass R. Miller at the Systematic Entomology Laboratory, Beltsville, Md., is the USDA expert on mealybugs. He confirmed that the mystery insect is the papaya mealybug, Paracoccus marginatus.

Miller says the Bradenton sample was the first time the papaya mealybug was found in the continental United States. It's considered to be a serious pest of papaya in several of the Caribbean Islands. It's also been reported to cause damage to papaya and cassava in Mexico.

Mealybugs damage the papaya plant by sucking its juices and excreting a clear, gooey substance called honeydew. They become so abundant that their bodies and wax color the fruit white, making the papaya unsalable.

Miller's research provided USDA's Animal and Plant Health Inspection Service (APHIS) details on the pest's hosts and distribution, as well as the means to identify and distinguish it from other scale species. Last June, APHIS sent Miller to Mexico, where he traveled across the country to search for possible controls.

There, Miller and Mexican colleagues collected 40 samples of parasites that included three wasps with potential as biocontrol agents. Miller asked his ARS colleague, parasitic wasp expert Michael E. Schauff, to identify and classify the wasps and other possible parasites in the samples.

Schauff and a British colleague identified the three wasps as belonging to the same family. They say some may be new to science, but all three cause the mealybug to mummify.

Miller also sent live samples of the wasp parasites and other potential biological control agents to ARS entomologist Lawrence R. Ertle in the ARS Beneficial Insects Research Unit, Newark, Del., where the parasites could be reared.

ARS is USDA's chief research agency.

For more details, see the May issue of Agricultural Research.

Scientific contact: Douglass R. Miller, ARS Systematic Entomology Laboratory, Beltsville Md.; (301) 504-5895, fax (301) 504-6482, [email protected].