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Weighing Neonics

Emily Unglesbee
By  Emily Unglesbee , DTN Staff Reporter
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Two studies reporting more ill effects on bees from neonicotinoids could sway public opinion, but the studies' impact on U.S. agriculture is less certain. (DTN photo by Pamela Smith)

ST. LOUIS (DTN) -- Don't be surprised if the public starts associating neonicotinoids with the tobacco industry.

A new study in the journal Nature showing that the chemicals can have an addictive quality for bees has been lighting up headlines from media outlets around the country, with varying levels of accuracy.

From the Huffington Post's flashy -- but shaky -- conclusion ("Common Insecticide Affects Bees Like Cigarettes Affect Humans, Studies Find") to the Guardian's more straightforward take ("Bees May Become Addicted To Nicotine-Like Pesticides, Study Finds"), the comparison could be seeping permanently into the minds of readers.

At the same time the image of cigarette-puffing bees began circulating, another Nature study showing that wild bees are negatively affected by a canola neonicotinoid seed coating hit the presses.

What this new research means for the U.S. agricultural industry is not clear yet. The conclusions of the study on addiction don't necessarily relate to corn and soybean crops, and the influence of wild bee species from the other study isn't well studied in row crop agriculture. But both studies add to the growing evidence of neonicotinoid risks to non-target insects, and at least one key governmental agency is paying attention.

The EPA is currently conducting a re-registration review of neonicotinoids, which has been fast tracked and prioritized by the agency thanks to the growing controversy over the safety of the insecticides. As part of the risk analysis portion of the review, EPA officials will examine these new studies and weigh the dangers they present, the agency confirmed to DTN in an email.

What will they find? Are bees really turning into nicotine addicts, always searching for neonic-laced nectar to feed their next buzz?

Not quite. What a group of UK researchers did find was that bees were not repelled by neonicotinoid levels found in the nectar of flowering plants. Specifically, the scientists offered honeybees and bumblebees two sugar concoctions, called sucrose solutions, designed to mimic nectar. Half of the sucrose solutions were laced with a range of neonicotinoid concentrations, some mimicking levels that have been reported in fields along with some higher concentrations. The other sucrose solutions were left untainted.

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The scientists discovered that the bees actually preferred the neonic-laced sucrose solutions, in the sense that they fed on them longer even though they ultimately took in less food.

"It's important to note that this did not show attraction [to neonicotinoids]," Purdue University entomologist Christian Krupke explained to DTN. "It's not like you'll see bees actively moving toward these plants and favoring them over others, but all things being equal, they will feed more and longer on the neonic-treated plants."

Only the highest dose of neonicotinoids -- levels well above what has been documented occurring in fields -- actually resulted in bee deaths, Newcastle University scientist Geraldine Wright (one of the study's authors), told DTN. But the other levels of neonicotinoids, which the bees preferred to linger upon, "have been shown to affect other behaviours, such as navigation, motor function, and learning and memory," in past research, she noted.

As far as U.S. row crop agriculture goes, "I think our work mainly applies to situations where bees visit flowers to obtain nectar and perhaps also pollen," Wright clarified. That means it applies less to corn and soybean fields (where neonicotinoids are widely used) but very much so to canola fields, a popular foraging option for bees.

The fact that the honeybees ate less of the neonic-laced sucrose solutions -- a point largely ignored by media accounts of the study -- could affect how much reaches the colony, but more research is needed, Wright said. "It is possible that the fact that the forager bees are made ill by the ingestion of the pesticides means that they both eat less but also are less likely to return back to the colony," she noted. "Bees forage not just for themselves but also for other colony members. They collect food and bring it back to the colony. To understand if their exposure to neonicotinoids affected the collection of solutions containing neonicotinoids, we would have to test this explicitly."

The other Nature study analyzed 16 canola fields in Sweden, half of which were planted with neonicotinoid- and fungicide-coated seed and the other half planted to seed with only the fungicide coating. The scientists analyzed the health of nearby honeybee and bumblebee colonies, as well as the behavior and survival of solitary bees and wild bee species.

The researchers couldn't find any significant difference between honeybee colonies that fed on the treated and untreated canola, but the neonic-treated fields "reduced wild bee density, solitary bee nesting, and bumblebee colony growth and reproduction under field conditions," they concluded.

Again, the application to large-scale American corn and soybean row cropping isn't clear, largely because we don't know a lot of about how non-honeybee pollinators interact with this landscape, Krupke noted. "To say that wild bees have no role or benefit to ag would be wrong -- we know they do but we haven't harnessed it fully and measured it to the same degree that we have on the honeybee side," he said.

A survey led by Krupke in Indiana last summer has opened a small window into the role they might play, however. In a field of flowering soybeans, surrounded by large, row-cropped fields, Krupke and fellow researchers counted 28 different species of non-honeybee pollinators visiting the flowers. "It was surprising and a lot more than I would have thought," Krupke recalled. "And it raises the question -- are they having any benefit for yield?"

Answers to this question and more are likely to slowly surface, as public and government scrutiny encourages more research on neonicotinoids.

When the EPA hands down its verdict on the chemicals in the next year, it might be the agency's assessment of the chemicals' benefit to pest management that drives their decision, Krupke noted. The agency and many university scientists have roundly criticized the need for neonicotinoids in soybean seed treatments. If the EPA determines that the risk to pollinators outweigh the benefits to agriculture, serious changes to the regulation of neonicotinoids could be ahead.

"I think a lot of what the regulatory side will pivot on is demonstrations of benefits," Krupke concluded. "All these pesticides have risks to bees and other things, but what are we getting on the positive side of the ledger -- what are we getting in terms of pest management benefits? I think the risks are being fleshed out more and more every day, but the benefits are still lagging behind in clarity."

You can find abstracts of UK researcher's study on the addictive nature of neonicotinoids here: http://goo.gl/…, and the Swedish canola study here: http://goo.gl/….

Emily Unglesbee can be reached at emily.unglesbee@dtn.com.

Follow Emily Unglesbee on Twitter @Emily_Unglesbee.

(PS\SK)

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Curt Zingula
5/8/2015 | 6:49 AM CDT
A study I read claimed that neonic seed treatments only exhibited 2 ppb in the plant's flowers - far below toxic levels. Also, I've always wondered how I can spray insecticide on a field for soybean aphids and still have good pollination - are we placing too much emphasis on a single pollinator? Witch hunters tell us that w/o honeybees life on this planet will become extinct. However, honey bees are actually an invasive species to this country.