Link to Owner Dr. Robert B. Pamplin Jr.



Dead bumblebees found under flowering European linden trees in Wilsonville and Hillsboro should spark action.

The dead bees in Wilsonville were apparent victims — following Oregon Department of Agriculture (ODA) analysis of dead and dying bees, and tree flowers and foliage — of an illegal application of a neonicotinoid pesticide.

Besides taking the unusual step to protectively wrap the 55 linden trees in Wilsonville and one tree in Hillsboro to exclude further insect visitation, the ODA enacted a temporary six-month ban on the use of 18 pesticides with the neonicotinoid dinotefuran on ornamentals.

Although unlikely to seek regulatory activities against homeowners, the ODA made it clear that licensed pesticide applicators “would be violating Oregon regulations if they use dinotefuran in the next 180 days.”

We may never know whether there is a direct link between the massacre of more than 50,000 bumblebees in Wilsonville due to careless use of a pesticide known to be “highly toxic to bees” and to the loss of bumblebees in Hillsboro.

A common dominator, however, is the pesticide dinotefuran (trade name “Safari”). In Wilsonville, 55 parking lot trees were sprayed while in full bloom. The spray application designed to eliminate honeydew-secreting aphids was presumably conducted due to customer complaints of honeydew on car windshields.

The same pesticide was sprayed on the trunk and roots of 200 Hillsboro linden trees in March, which was not a violation of the label.

ODA analysis of Hillsboro bees and trees is forthcoming. Were the dead Hillsboro bumblebees another “unintended consequence” of pesticide use? Were bumblebees once again non-target victims?

We need to educate ourselves about pollination’s role in our lives and what consequence pesticides might play in normal functioning ecosystems. We should resolve to never apply a pesticide to trees or flowering plants as we run the risk of harming necessary pollinators. But Hillsboro may also demonstrate that we should carefully evaluate use of pesticides and whether what we hope to accomplish by use of such chemicals is really in our own best interest.

The neonicotinoid pesticides, the most widely used insecticide in the urban environment, are long-lasting compounds that have been implicated in the global decline of honeybees.

In Wilsonville, the magnitude of the bee massacre demonstrates the critical nature of human reliance upon pesticides and their fearful potential to kill beneficial insects.

Consider that one-third of foods we consume are dependent upon insect pollinators. Of 100 crops providing 90 percent of the world’s food, 71 are pollinated by bees.

Neonicotinoid insecticides, with active ingredients like imidacloprid, dinotefuran, thiamethoxam, and clothianidin, can be purchased in most hardware stores and nurseries under various trade names. Stores that sell pesticides or treated materials should be required to post more prominent information on their potential to harm pollinating insects. When buying plants or gardening, avoid materials treated by nursery and retail stores with neonicotinoids. Ask — and if they can’t tell, shop elsewhere.

Scientists at Xerces Society, Portland’s world renowned center of excellence on conservation of insects and other invertebrates, are calling on Hillsboro and county authorities to consider banning the cosmetic use of insecticides on city- and county-owned lands, and the federal Environmental Protection Agency should step up its review and seek to determine what role pesticides may play in bee deaths.

Who will speak for the dead bumblebees beneath the lindens? How many more times will this occur before we decide to speak out?

Dewey Caron retired after 42 years teaching entomology and beekeeping and is a volunteer affiliate professor in Oregon State University’s horticulture department. He lives in Tigard.

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