Researchers Discover Pesticide Build-Up Could Lead to Poor Honey Bee Health

Penn State researchers have discovered that pesticide build-up could lead to poor honey bee health. The researchers analyzed pollen, brood, adult bees, and wax samples. The results showed unprecedented levels of fluvalinate and coumaphos - pesticides used in the hives to combat varroa mites - in all comb and foundation wax samples. They also found lower levels of 70 other pesticides and metabolites of those pesticides in pollen and bees. While the researchers expected the presence of the chemicals available to treat varroa mites in the hives, the other pesticides' levels were surprising. All of the bees tested showed at least one pesticide and pollen averaged six pesticides with as many as 31 in a sample.

"We already had in place ways to test for viruses, bacteria and fungi, but it was difficult to find an analytical laboratory that could analyze for unknown pesticides," says Christopher A. Mullin, professor of entomology. "We needed them to take a comprehensive look at all pesticides, not just those associated with beekeeping."

They eventually turned to the National Science Laboratory of the U.S. Department of Agricultural Marketing Service that already tests commodities such as milk, fruits, and vegetables to allow them to meet national and international standards. The researchers, including Roger Simonds, a chemist at the National Science Laboratory decided on a modified QuEChERS method because it uses smaller samples. They coupled this with GC and LC to develop methods of analyzing pollen, bees, and wax.

While beekeepers will have a difficult time controlling pesticide exposure outside the hive, the researchers tested a method for reducing the acaricide load in beeswax. Using gamma radiation from a cobalt 60 source housed at Penn State's Breazeale Reactor, they irradiated the sheets of beeswax that beekeepers use as the structural foundation for the bees to build their combs. They used radiation levels at the high end of that used to irradiate foods. Irradiation broke down about 50 percent of the acaricides in the wax.