25,000 bumblebees killed in Wilsonville

WILSONVILLE, OREGON -- June 18, 2013 -- A bumblebee dies after falling off a Landen tree at Town Loop Shopping Center parking lot. An estimated 25,000 bumblebees were found dead beginning Saturday, the largest known incident in the United States.

(Motoya Nakamura)

In response to a

, the Oregon Department of Agriculture

Thursday on 18 insecticides with the active ingredient dinotefuran.

An estimated 50,000 bees and other insects died in a Wilsonville shopping center parking lot last week. A landscaper sprayed 55 flowering European linden trees with Safari pesticide on June 15. State officials confirmed the dinotefuran insecticide was responsible for the deaths.

are also being investigated.

"We're not trying to get it off the shelves, or trying to tell people to dispose of it, we're just telling people not to use it," said Bruce Pokarney, a spokesperson for the department of agriculture.

While Pokarney acknowledged it would be difficult to cite individual homeowners, he said licensed pesticide applicators would be violating Oregon regulations if they use dinotefuran-based insecticides on plants in the next 180 days.

The temporary ban only affects pesticide use that might harm pollinators, like bumblebees. Safari is one of the insecticides restricted by the Agriculture Department. Most of the restricted insecticides are used primarily for ornamental, not agricultural, pest control.

Dinotefuran use in flea collars, and ant and roach control will still be allowed.

The Department of Agriculture will reassess the temporary restriction after officials finish their investigation into the pesticide applications in Wilsonville and Hillsboro. These inquiries could take up to four months.

The Valent U.S.A. Corporation, which distributes Safari, could not be reached for comment, but the company

earlier this week about the bee deaths.

"We are actively conducting outreach with our customers and industry partners to reinforce the importance of responsible use according to label guidelines," the statement said.

Dinotefuran is a member of a type of insecticides called neonicotinoids. Neonicotinoids can be broken down into two groups: the nitro-group and the cyano-group. Dinotefuran is a member of the nitro-group, which has been shown to be more poisonous to pollinators. The European Union

earlier this year on three other nitro-group neonicotinoids, which goes into effect this December.

The Washington state Department of Agriculture decided

earlier this month. Instead, the Washington department will "urge the U.S. Environmental Protection Agency to consider whether additional use restrictions are needed when the products are applied to ornamental plants."

The EPA is

on pollinators, since research and beekills incidents highlight "the potential direct and/or indirect effects of neonicotinic pesticides," its website said.

The Portland-based Xerces Society, who originally reported the Wilsonville bee deaths to the Department of Agriculture, is working with a congressional office on legislation about pollinators and pesticide use, said Scott Black, Xerces' executive director.

"We hope that this is just the start, that now we can take a look at this entire class of pesticides called neonicotiniods and really scrutinize them for their potential impact on these beneficial insects," Black said.

--Elizabeth Case