University of California-Davis
PORTLAND — The bumblebee deaths in spraying incidents last summer have put Oregon in an uncomfortable spotlight and caused federal and state labeling changes while researchers continue probing the effect of neonicotinoid insecticides, an Oregon State University professor said.
Neonicotinoids were introduced in the 1990s and gained favor because they can be applied at lower rates than other pesticides and are less toxic to mammals — a big issue for farmworker safety, said Dave Stone, an environmental and molecular toxicology professor at OSU. “Neo-nics” as they are often called, kill insects by binding to and closing neuro-receptors.
Activists and some researchers question whether pesticides may be responsible for Colony Collapse Disorder, which has wiped out honeybee hives and threaten crops that rely on pollenization by bees. The issue came to the fore in Oregon when thousands of bumblebees died when landscapers sprayed trees at a Target parking lot in Wilsonville.
The Oregon Department of Agriculture fined the applicators and implemented an Oregon-specific label regarding neonicotinoid ingredients dinotefuran and imidacloprid. The label prohibits application on linden, basswood or Tilia species of trees.
Speaking at the annual Northwest Agricultural Show in Portland, Stone said the applicators weren’t following the previous labeling requirements. “We expect that with homeowners, but to have commercial applicators not follow the label is obviously not good news,” he said.
The federal Environmental Protection Agency also made label changes, putting a honeybee icon on the label and warning of the impact on foraging pollinators.
Stone said honeybees are potentially exposed to pesticide residue through direct contact with spray, contact with plants that have been sprayed or ingestion of nectar, pollen or dew on the plant. The cumulative impact is “certainly not clear at this point,” he said.
It’s also unclear whether neonicotinoids are persisting longer in the environment that previously thought, he said. Continued research is necessary, especially to determine to what level bees are exposed to neonicitinoids in the field, he said.
“This issue couldn’t be more visible right now, and Oregon is playing a big part in this,” Stone said.