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Hillsboro bee deaths still a mystery

Researchers: Safari pesticide may not be culprit there


by: PAMPLIN MEDIA GROUP PHOTOS: CHASE ALLGOOD - Workers put a huge net over this tree in downtown Hillsboro to keep bees away. Though the tree was sprayed with the pesticide Safari earlier, experts arent yet sure what killed thousands of bumblebees there two months ago. Below, a solitary bee crawls along the ground nearby. Two months after thousands of bumblebees died in Hillsboro, scientists and Oregon Department of Agriculture officials are faced with more questions than answers.

After about 50,000 bees were found dead in a Wilsonville Target store parking lot, scientists determined that Safari, a dinotefuran pesticide sprayed on linden trees to control aphids, had killed them.

A short time later, thousands more dead bees were found under a linden tree in downtown Hillsboro. Even though the Hillsboro linden trees were sprayed with Safari several months before the bee deaths were reported, it’s still undetermined whether the pesticide killed the bumblebees.

While many observers expected conclusions by now on the cause of bee deaths in Hillsboro, they’ve had no such luck.

Bruce Pokarney, Oregon Department of Agriculture director of communications, estimates the agency will release more information in September.

“There are still a lot of questions to be answered about what happened,” Pokarney says. “We’re still not anywhere close to knowing what happened there.”

Along with the agriculture department, a field-crop entomologist at Oregon State University, Sujaya Rao, is trying to find answers.

“Maybe this is widespread and we just haven’t noticed yet,” Rao says of the bees falling from the trees.

by: PAMPLIN MEDIA GROUP: CHASE ALLGOOD - BeesTo confirm the bumblebees feeding on Hillsboro linden trees died from Safari, Rao says she’d have to evaluate the trees’ nectar and the pollen to see if she could find any trace of the pesticide. But by the time the bumblebee deaths were reported and she collected samples, the blooms were on their way out and the nectar was all dried up.

Pesticides like Safari, Rao says, are designed to be absorbed into the plant or tree — as opposed to just working topically and killing insects on contact. As a result, aphids bite into the plant and suck out the pesticide, which kills them.

Extensive research has not been done to examine how long the chemical sticks around in the linden trees after they are sprayed, Rao says.

Safari is considered a reduced-risk pesticide, but that’s only reduced risk for wildlife, Rao says. The pesticide is, after all, designed to kill insects, and bees are insects.

Her future research will include putting the pesticide in a sugar solution and observing whether bumblebees die after they feed on it.

But Rao has to take a complete look at the conditions surrounding the deaths.

Not all bees affected

She also wants to explore why thousands of bumblebees died in Wilsonville and Hillsboro, yet honeybees apparently were left unscathed.

Researchers in Europe reported the presence of a sugar found in stressed linden trees — mannose — that they believed to be toxic to bumblebees, but not honeybees, Rao says. In addition, stressed plants — perhaps due to hot weather — often produce more flowers. It could be that the Hillsboro blooms attracted more bees than usual, but there wasn’t sufficient nectar, so they starved, as indicated by another European study. There also could be synergistic interactions between stress effects and the pesticide.

Scott Black of the Xerces Society for Invertebrate Conservation says the state agriculture department is looking into at least a dozen bee kills that have been reported on its website, www.xerces.org.

“There’s a variety of reasons people find dead bees, so it’s hard to say what the causes are,” Black says.

Coming to conclusions and developing solutions may take awhile, but there has been action.

Temporary regulations

In late June, the agriculture department issued a temporary restriction (not a ban) on 18 pesticide products that contain dinotefuran. That lasts for 180 days, while officials investigate the bumblebee deaths.

Dinotefuran belongs to a group of chemicals called neonicotinoids.

U.S. Rep. Earl Blumenauer, D-Portland, recently introduced the Save America’s Pollinators Act of 2013, which directs the Environmental Protection Agency to “suspend use of the most bee-toxic neonicotinoids for use in seed treatment, soil application, or foliar treatment on bee-attractive plants within 180 days, and to review these neonicotinoids and make a new determination about their proper application and safe use.” The act cites the bumblebee die-offs in Hillsboro and Wilsonville as well as “disturbing preliminary research” of the chemical’s impact as reasons for a second look.

“We firmly believe these insecticides should be restricted from use on bee-pollinated plants until the EPA says they’re safe,” Black says. “Dozens and dozens of scientific studies” show this class of chemical is problematic for pollinators, he says.

The Xerces Society, based in Portland, is pushing its Bring Back the Pollinators Campaign, which calls people to sign a pledge to protect pollinators and create a pollinator-friendly space by planting flowers and trees that provide nectar and pollen, and reducing pesticide use.

“The good news is anybody can take action — whether you have a yard, garden, farm or manage a park, you can stop using pesticides and plant flowers,” Black says.

For some, there’s a light at the end of a dark tunnel.

“There’s a lot of momentum to better understand the total impact of these insecticides,” Black says. “We never want to see this happen again, and people all around the Portland metro area are talking about it.”

“Although the situation is very sad,” Rao says, “where else would you find such a high population of bumblebees and such conscientious citizens?

“It’s very Oregonian.”