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It turns out that bees, like humans, may be addicted to the chemicals that bring about their demise.
Two studies into the effects of neonicotinoids, a class of chemical that accounts for one fifth of the world's insecticides, have revealed that not only might the chemicals be harming bees' ability to reproduce, but they may also be highly addictive to the insects as well, much like nicotine is for humans.
That's perhaps not all that surprising, considering that neonicotinoid is chemically similar to nicotine and literally means "new nicotine-like insecticides."
The two new papers, published this week in the journal Nature, are perhaps the strongest evidence yet that neonicotinoids bear some responsibility for the ongoing collapse of bee populations around the world — a phenomenon commonly called "colony collapse." Human-managed honeybee populations fell 23 percent in the winter of 2013 and have fallen by similar percentages every winter for nearly a decade.
'This has implications for at least 40 million acres where neonicotinoid-coated crop seeds are planted in the United States.'
While scientists have previously named neonicotinoids as a key cause of honeybee collapse, the two new studies shed light on the toxin's effect on wild bees, which have received much less scholarly attention.
"[These studies] show the wild bees are more sensitive than honeybees are," Christian Krupke, an associate professor in the department of entomology at Purdue University, told VICE News.
In the first study, led by a team at Lund University, researchers studied honeybees, bumblebees, and solitary bees at 16 different canola seed fields in Sweden. The fields were studied in pairs, with canola seeds in one field coated with neonicotinoids and seeds in the other only coated with fungicide.
Researchers found that bumblebees and solitary bees foraged for pollen less frequently in the Elado fields and discovered a marked decline in reproduction among both bee species compared to their counterparts in the non-Elado fields. Honeybees, on the other hand, exhibited no immediate effects from their exposure to the neonicotinoids — but researchers said that didn't preclude possible long-term effects.
Maj Rundlöf, the lead researcher of the Lund study, told Vice News that another risk was that bees could be spreading around neonicotinoids during their pollination process.
"Bees spread pollen between flowers when they perform their pollination services and they could in this way spread some of the pesticides," she said.
However troubling Rundlöf and her team's findings might be, neonicotinoids boosters have maintained for years that bees actively avoid nectar and pollen laced with the insecticide because of the taste.
And that's where the second Nature study comes in.
Researchers from Newcastle University found that not only do honeybees and bumblebees not avoid the pesticides — they prefer them.
When honeybees and bumblebees were presented with the option of consuming sucrose on its own or laced with certain neonicotinoids, they uniformly chose the insecticide-laced syrup, likely because of its nicotinic effects, even though it reduced their appetites and killed them quicker — sort of like smoking cigarettes.
Researchers matched the concentration of insecticides in the sucrose to what is usually found in nectar-producing plants treated with neonicotinoid, meaning the bees are likely to prefer it outside the lab, too.
Since the chemicals were introduced to the market in the 1990s, scientists and conservationists have grown increasingly concerned about their impacts on bees, which ultimately led the European Union to ban certain neonicotinoids in 2013.
The chemical industry, including the multinational chemical and pharmaceutical behemoth Bayer, which first patented neonicotinoids for commercial use, criticized the EU ban as reliant on weak studies.
Aimee Code, a pesticide program coordinator for the Xerces Society who was not involved with either study, said that while the findings were troubling, it also did a service by focusing on the plight of bumblebees and solitary bees, which are responsible for most of the pollination resulting in the produce we eat, but are underrepresented in research.
"These studies further strengthen what is already compelling body of information showing the risk of neonicotinoids to bees," she told Vice News. "This has implications for at least 40 million acres where neonicotinoid-coated crop seeds are planted in the United States."
But Rundlöf, the leader of the first study, made clear that her findings weren't an indictment against all pesticides.
"[Our study] should be weighed together with other pieces of evidence on the subject," she said. "In my view, we should consider pesticides as one of several available tools to control pests."
Follow Aaron Cantu on Twitter: @aaronmiguel_
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