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Gel Could Stop Two Mites With One Treatment

By Jill Lee
November 24, 1997

Domestic honey bees can be protected from both tracheal and varroa mites--two major pests of this crucial insect--with an application of formic acid mixed with a food-grade gelling agent.

Scientists with USDA’s Agricultural Research Service say the gel formulation could smooth the path to U.S. registration of formic acid to combat both mites. That’s because the gel would reduce a beekeeper’s contact with the acid.

The ARS researchers filed a patent on the technology last week. They say beekeepers could alternate the formic acid gel treatment with the industry’s standard varroa mite-fighter, fluvalinate. This would help slow the varroa mite’s progress toward fluvalinate resistance in this country.

U.S. beekeepers get nervous when they read about varroa mites in Italy and France developing resistance to fluvalinate, because it is currently the only U.S.-registered pesticide against varroa mites. Menthol is the approved product for treatment of tracheal mites.

Formic acid has proven effective outside the U.S. against both varroa and tracheal mites. But liquid formic acid evaporates quickly and must be re-applied four to five times per season.

The ARS scientists say sealing the formic acid and gel in a plastic bag would give beekeepers a product requiring less handling. The bag could be sliced open inside the hive, allowing the formic acid to evaporate and leave behind only a harmless residue. In field tests, the experimental product killed up to 84 percent of the varroa mites and 100 percent of the tracheal mites, an extra benefit.

Worker bees gather nectar for honey and pollinate plants during the last part of their life cycle. Mites not only kill the bees at this critical time, but also quickly spread throughout other hives. This can have effects beyond destroying a beekeeper’s expensive investment. California, for example, uses half a million bee colonies annually to pollinate its almond crop alone.

Scientific contact: Mark Feldlaufer , Bee Research Laboratory, USDA, ARS, Beltsville, Md. Phone: (301) 504-8205; fax: (301) 504-8736, e-mail: