Responding to mass kills of bumblebees last June, the Oregon Department of Agriculture has banned the use of two types of pesticides on Tilia trees commonly used in landscaping.
Beginning next year, Oregon will require an unusual state-specific label on the use of pesticides containing the active ingredients dinotefuran and imidacloprid. Both are neonicotinoids, which many suspect are linked to colony collapse disorder among honeybees and are harmful to other pollinators as well.
In addition, ag department Director Katy Coba has asked the U.S. Environmental Protection Agency to evaluate the active ingredients to determine if their use should be limited nationally. Information about pollinator protection will be included in the testing and recertification process required for licensed pesticide applicators in Oregon.
The state action bans the pesticide use on linden and basswood trees, which are among the Tilia species. Thousands of bumblebees died after foraging on landscaping trees in the Portland suburbs of Wilsonville and Hillsboro last June, setting off a public outcry. Landscapers intending to control aphids had sprayed the trees with pesticides. In response, Oregon issued a temporary restriction on the use of pesticides containing dinotefuran; the new announcement expands the prohibition to include imidacloprid.
The ag department believes the trees possess a natural toxicity to bumblebees that was exacerbated in combination with the pesticide. An investigation is expected to be completed by mid-December.
The Xerces Society, a Portland-based organization that works to protect pollinators and other invertebrates, welcomed the ag department’s action and asked for more.
“We believe we should go further and look at other (plant) species that attract bees and see where we may need similar bans,” Executive Director Scott Black said.
Black said he appreciates Coba pressing the issue with the EPA, and hopes it will cause the agency to review neonicotoids sooner than 2018 as it is now scheduled.
“We think the whole process is backwards,” Black said. “We should have studied these chemicals and looked at the effects before we approved them. We’ve approved them, and now in some cases are finding they shouldn’t have been approved for those uses.”
Black said neonicotoid use on corn crops in the U.S. and Canada has killed millions of bees. The pesticides travel into plants’ pollen and nectar, and are taken in by foraging bees, he said.
The Xerces Society hopes to work with farmers to find pesticide options, Black said. They aren’t used on organic crops, but he acknowledged that not all growers can or will adopt organic methods. The group has not called for an outright ban on the pesticides, because other non-crop uses may be viable.
“We can look at what the suite of options are,” he said. “We need to take a deeper look and scrutinize these chemicals.”