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10 Years Later, California Still Reviewing Pesticide That Kills Bees

Holding a bee with tweezers in a UCSD laboratory on Feb. 26, 2018.

Photo by Matthew Bowler

Above: Holding a bee with tweezers in a UCSD laboratory on Feb. 26, 2018.

Warren Treisman was fascinated by the bees he kept in a backyard beehive of his Del Cerro home. The hive rested against a fence on the west side of his backyard, behind a Jacuzzi. Intrigued by his sister’s attempts to keep a hive in a much colder climate back east, Treisman set up his own colony and began harvesting honey.

”Usually, you just watch them and see that the activity is normal and everything’s OK,” Treisman said.

He grew accustomed to the activity the hive brought to his yard.

But a check of the hive in February revealed everything was not normal. He noticed dead bees on the ground. A lot of dead bees.

“It’s just devastating to see all those bees on the ground, dead or dying,” Treisman said.

Thousands of the bees littered the ground near the hive. Occasionally, a bee would stumble out of the hive and fall dying to the ground. Treisman doesn’t know what wiped out the colony because toxicology tests cost about $1,000 for a single bee, but he thinks it is unlikely that parasites or a disease are responsible.

The hive was wiped out quickly and that raised a red flag for University of California San Diego Biological Sciences Researcher James Nieh.

Reported by Matthew Bowler

Researchers link common insecticide to bee deaths

“If it was something that occurred within 24 hours where suddenly you had hundreds or even thousands of bees dying. It does suggest there was a chemical basis for it,” Nieh said.

One widely-used insecticide class known as neonicotinoids has been increasingly linked to bee deaths.

Large companies like Syngenta and Bayer began selling products like Merit, Venom and Cruiser in the mid-1990s. They are effective and widely used in agriculture and by consumers.

“We have them in our gardens,” Nieh said.

“They’re used to treat grass. To treat the plants that we plant in our plant beds. They’re in our homes. Some of them are actually used as flea medications for dogs and cats,” Neih said.

The product can be sprayed on plants, injected into the soil or even be used to treat a seed.

“So what you can literally do is put a small amount on a seed. Plant the seed. Water it. It turns into a big plant and every cell in that plant has a tiny amount of that insecticide,” Nieh said.

That means neonicotinoids can live in a neighborhood as long as the treated plant is alive.

And while the dose in each cell is small, thousands of forager bees can pick up the chemical and bring it back to the hive. It can accumulate there until it reaches a critical level.

Fellow UC San Diego Researcher Simone Tosi has worked with Nieh to document the impact of neonicotinoids on bees.

In the lab, he leaned over a small clear box hoping to grab a bee with a pair of tweezers.

“So now is the difficult part in which I need to capture her,” Tosi said.

Tosi has glued a plastic tube onto the bee’s back so he can put the insect on a special harness.

“And then I put the bee like that. This happens. It starts flying,” Tosi said.

The little bee velodrome, which looks a bit like a round hat box, allows researchers to measure speed, strength and endurance while controlling the environment. Controlling the variables is the key.

“Because bees can visit very wide areas around a colony, and you don’t know where is she going. What is she feeding on? And basically, a colony can visit millions of flowers per day,” Tosi said.

Insecticide hurts bees and can kill them

The neonicotinoids are less toxic to bees than what came before, Tosi said, but there are significant sublethal effects. The insecticide can impair flying and hurt the bee’s ability to find the hive. It can also accumulate to toxic levels inside a hive.

“Pesticides do not discriminate between good and bad insects. So they would kill the bad insects, the pests. But they would also kill the bees or cause negative effects on bees. Because those bees eat parts of the plant,” Tosi said.

Photo by Matthew Bowler

Dead bees litter the ground at a Del Cerro home on Feb. 26, 2018.

California Regulators still reviewing

The California Department of Pesticide Regulation began reviewing the insecticide in 2009 after getting a number of reports linked to ornamental plants.

“Does it really affect bees or does it really affect pollinators is the question that we raised,” said Mary Lou Verder Carlos, the chief science advisor and assistant director for the Department of Pesticide Regulation.

Regulators are working with industry and agriculture to determine if usage rules need to be changed.

“We’re thinking may reduce the amounts of pesticides that can be used at certain times. Of course, they still have to be effective, even if you reduce the rates. And then, it could be that they will be strictly applied only at nighttime. Will not be applied during bloom at all,” said Verder Carlos.

State officials will conclude their review of neonicotinoids this summer, more than a decade after deciding that there were enough concerns about these insecticides to look closely at how they are used.

It remains to be seen if the review will change how the chemicals are used, now that there is definitive proof that they hurt bees.

Warren Treisman was fascinated by the bees he kept in a backyard beehive of his Del Cerro home. The hive rested against a fence on the west side of his backyard, behind a Jacuzzi. Intrigued by his sister’s attempts to keep a hive in a much colder climate back east, Treisman set up his own colony and began harvesting honey

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