The scientists recently took wax, pollen, and bee samples from more than 110 hives across the state and have analyzed about half of them for pesticide residues.
“We did not find excessive amounts of agricultural pesticides in the hives, but we did find a significant amount of beekeeper-applied miticide,” said Fell, professor emeritus of entomology in the College of Agriculture and Life Sciences.
Intended to kill the invasive, parasitic varroa mite, miticides can also be damaging to bees. Fell urged beekeepers to sample their colonies to determine mite infestation levels before treating. If treatment is necessary, beekeepers should use a miticide that does not cause residue problems, such as formic acid.
As more information emerges on the spread of the Zika virus, Fell also encouraged the public to be mindful that mosquito pesticides are toxic to honeybees and should only be applied when absolutely necessary.
Fell and Brewster, who is also a professor of entomology, are now in the third year of a five-year, $1.4 million project funded by the Virginia Department of Agriculture and Consumer Services to better understand honeybee decline.
Their next step is to examine select hives more intensely to determine other key factors involved in honeybee loss. The approximate rate of hive loss in Virginia is more than 30 percent per year, and continued losses are expected to drive up the cost for important crops that bees make possible, such as apples, melons, and squash.
While it is good news that agricultural pesticides are not wholly to blame, it also means that the problem is more complicated than expected, and the researchers have their work cut out for them.
“Landscape change, lack of habitat, and climate change’s impact on floral bloom seasons are all factors that impact honeybees that we need to learn more about and potentially develop strategies around,” Brewster said.
Tim Kring, department head of entomology, said he will hire two new pollinator scientists — one researcher and one Extension specialist — in the coming year.