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Daily News Archive
From December 13, 2001

Parasitic Wasps Protect Poinsettias from Whitefly Damage

Poinsettias, the red, white and pink potted flowers that seem to be everywhere this time of year, often find themselves infested with little tiny white bugs called silverleaf whiteflies. Given that poinsettias are the top-selling potted plant in the United States, selling over 80 million flowers each year, solving the whitefly problem is no small feat.

Despite this pest problem, people don't necessarily have to bring home a pot contaminated with toxic pesticides for the holidays this year. According to the Environment News Network (ENN), one of the most effective weapons against the whitefly is a parasitic wasp, Eretmocerus eremicus, who is harmless to humans but deadly to whiteflies. Female wasps lay their eggs in whitefly young. Wasp young then grow inside the developing whiteflies, eventually killing them.

"We anticipate that growers may become more interested in using the wasps when whiteflies become resistant to the insecticide most commonly used today in poinsettia greenhouses," Gloria DeGrandi-Hoffman of the Federal Agricultural Research Service told ENN. Ms. DeGrandi-Hoffman and her colleagues developed user-friendly computer software called Biocontrol-Poinsettia that will help poinsettia growers determine how best to use the wasps.

Participants at the 19th National Pesticide Forum last May in Boulder, CO had a chance to see parasitic wasps up close. Barry Pawson, president of PNE, the company that produces the wasps, and Scott Harvey, an intergrated pest management professional at the University of Colorado (CU) showed wasps and explained the university's program to the conference participants. CU, which utilizes a range of least toxic pest management practices on campus, finds parasitic wasps particularly useful in laboratories and other sensitive areas.