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New Computer Program Helps Growers Protect Poinsettias

Colorful poinsettias are favorites because they rank as the nation’s top-selling potted flowering plant. But poinsettias, Euphorbia pulcherrima, are also a favorite of the silverleaf whitefly.

This greenhouse pest, known to scientists as Bemesia argentifolii, is no bigger than a ballpoint pen tip. It sucks juices from the poinsettia leaves and stems and weakens the plant, according to Agricultural Research Service entomologist Gloria DeGrandi-Hoffman, based at the agency’s Carl Hayden Bee Research Center in Tucson, Ariz.

To clobber the tiny whiteflies, DeGrandi-Hoffman and colleagues have developed user-friendly software called BIOCONTROL-POINSETTIA. It will help growers determine how best to use a wasp, Eretmocerus eremicus, a natural enemy of whiteflies. Female wasps lay their eggs in whitefly young. The wasp eggs then develop inside the whiteflies, eventually killing them.

The new computer model helps growers determine how many wasps to turn loose in their greenhouses to attack the whiteflies. It will also indicate when and how often they might use the wasps for whitefly control. The software augments the growers’ expertise and experience, giving them a resource for an objective analysis.

De-Grandi-Hoffman developed the software at the urging of colleagues John P. Sanderson at Cornell University, Ithaca, N.Y., and Roy G. Van Driesche at the University of Massachusetts, Amherst. Mark Hoddle, University of California, Riverside, along with Sanderson and Van Driesche, first discovered E. eremicus’ impressive capabilities as a biocontrol agent for whitefly.

To build the program, DeGrandi-Hoffman entered whitefly and wasp information, gleaned from years of work by Sanderson and others, into a mathematical form for the computer to analyze. The result sits on a single floppy disk and runs on any personal computer equipped with Windows 98 or later.

An article in ARS’s monthly magazine, Agricultural Research tells more.

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