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Neonicotinoid seed treatments: Effective crop protectants—or unnecessary, with potential collateral damage to bees?

Neonicotinoids, the world’s most popular class of insecticides, have been making headlines for the last decade due to concerns that they negatively impact bees. Now, a new debate has emerged in the fight over their use, pitting university entomologists against agricultural economists, the EPA against the USDA, and pesticide manufacturers against environmental activists. Farmers, as usual, are caught in the middle, trying to figure out how the conflicting narratives will impact them.

The question at hand: Do neonicotinoid seed treatments increase yields? If not, as some claim, reducing or eliminating their use in order to ease a potential stressor on bee colony health could be an easier decision for growers.

Nearly all corn and a majority of soybean seeds sold in the United States are coated with neonicotinoids, or “neonics”. Their main purpose is to fend off below-ground pests while the seeds are germinating, with the hope that the plant also absorbs some of the insecticide and expresses some of its pest-deterring effects as it’s growing. Neonic seed coatings are often preferred to spraying and the use of other insecticides because they’re effective at low concentrations and less toxic to mammals.

The most recent chapter in the debate erupted in May of this year, when Christian Krupke, an entomologist at Purdue University, and colleagues published a study comparing cornfields planted with untreated seeds to fields with neonic-coated seeds at three locations in Indiana over three growing seasons. They found no evidence of yield benefits from the seed treatments. Although the study was one of the first to show ineffectiveness in corn, contradicting previous research, the paper’s authors write that their study, along with studies on other crops, “suggest that the current use levels of insecticidal seed treatments in North American row crops are likely to far exceed the demonstrable need.”

Critics of the study, many tied to the agricultural industry, point to a 2014 report by AgInfomatics, an agricultural consulting firm, which reviewed over 1,500 field studies and found yield benefits for all crops studied, ranging from 3.6 percent for soybeans to 71.3 percent for potatoes (corn clocked in around 17 percent). They also surveyed farmers and found other financial benefits, such as not needing to spend the time and money that goes into scouting fields and spraying insecticides.

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From the 2014 AgInformatics report: Average yield benefit by crop for neonicotinoid insecticide treatments relative to untreated control treatments.

“The simple answer is farmers would not continue to buy them if they did not produce value,” explained Peter Nowak, a University of Wisconsin environmental studies professor associated with AgInformatics. Nowak sees insecticidal seed treatments as part of an emerging technological trend in agriculture where the seed, and treatments, is the future of row crop production.

But John Tooker, a Penn State University entomologist who studies neonicotinoids, thinks the AgInformatics study should be taken with a grain of salt because it was funded by pesticide manufacturers and was not published in a peer-reviewed journal.

“Time and time again, research in various sectors (biomedical, nutritional science, agricultural science, etc.) has shown that reports funded by the industry tend to support the industry perspective,” he told The Progressive Farmer in May. “This report certainly does that, and it is good to recognize that potential lack of impartiality.”

In response, Nowak said he’s tired of the “cheap shots” taken at the AgInformatics report.

“Show me something more robust and valid — there is none,” he said. “We have not (over) generalized from a single study as has been the case with the critics. Instead, we pointed out important nuances associated with neonicotinoid efficacy found across hundreds of studies.”

Researchers agree that neonicotinoid effectiveness depends on the crop and where it’s grown. For example, recent research has shown that neonic seed treatments have yield benefits for soybeans in the South, but convincing evidence to support their widespread use in northern states, where most US soybeans are grown, is harder to come by. This is likely because the warmer southern climate is more hospitable to early-season soil pests.

Krupke and Tooker are part of a group of entomologists in the Midwest that argues soybean seed treatments are largely unnecessary in their region. They say the plants are able to withstand early season pest pressure without inflicting economic losses. By the time more serious pests come along, such as the soybean aphid, the insecticidal effects of seed treatments have already worn off. Instead, they recommend an integrated approach that includes “rotating crops, conserving natural enemies, using soybean varieties with resistance to pests (soybean aphid) or disease (bean pod mottle virus), and scouting and applying insecticides at established thresholds.”

However, there are certain high-risk situations, such as food-grade soybeans or fields transitioning from pasture to soybeans, in which entomologists agree that treatments can be useful.

Related article:  Viewpoint: The dreaded 'green blob' is the most dire threat to bees

“I don’t recommend [neonicotinoid seed treatments], particularly for soybean, unless there is a demonstrated need,” said Iowa State entomologist Erin Hodgson.

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From a joint publication by 12 Midwest universities: There is little or no insecticide remaining in soybean plants by the time soybean aphid populations typically begin to increase.

A 2014 review by the EPA agreed, concluding that the seed treatments “provide negligible overall benefits to soybean production in most situations.” But USDA chief economist Robert Johansson wrote a stern letter to the EPA in response, stating that the USDA disagreed with the assessment, and criticizing the agency for adding “an additional and unnecessary burden” on farmers.

Farmers weigh in

The debate over neonicotinoid effectiveness highlights some of the unique challenges farmers face, and the difficult decision-making process inherent in the low profit margin, high-stakes world of modern agriculture.

Terry Daynard, an Ontario grain farmer and former University of Guelph crop science professor, sees neonic seed treatments as a low-cost insurance policy against a small but potentially devastating risk.

“I once lost several thousand dollars worth of corn when an unexpected soil insect pest destroyed much of the center of a field,” he said. “That’s the time when I decided to purchase all neonic-treated seed in the future.”

Maria Trainer, Managing Director of Science and Regulatory Affairs for Chemistry at CropLife Canada, which represents plant biotechnology companies, agrees.

“The unpredictable nature of soil insects is why growers have adopted treated seeds so widely,” she said. “Many of the pests that they protect against are found in the soil and cannot be treated with a spray because by the time a farmer identifies the pest problem, the crop is lost.”

Van Larson, an independent agronomist at Agronomy Services Plus in southern Minnesota, is skeptical of the entomologists’ research showing neonics don’t increase soybean yields, partly due to past experiences. In 2001, university researchers told him not to spray soybeans because it could harm beneficial insects. Then the aphids came.

“It was massive amounts of money that we lost listening to that suggestion,” he recounted.

Krupke, the Purdue entomologist, claims that many farmers aren’t aware that they’re buying neonic-treated seeds and are paying extra for it.

“Even if they do, they often have no other choice,” he said. “The market provides no easy option to buy untreated seed, especially in corn, so there is no basis to price compare.”

Farmers, however, don’t seem to be clamoring for untreated seeds at the moment.

“The reality is that farmers want this product,” Kevin Cavanaugh, director of research for Beck’s Hybrids, a seed company, told the Indiana Prairie Farmer. “I’ve yet to have the first farmer tell me that he doesn’t want neonic seed treatment on his seed.”

Paul McDivitt is a science and environmental writer based in St. Paul, Minnesota. He has a Master’s in environmental journalism from the University of Colorado. Follow him on Twitter @PaulMcDivitt

20 thoughts on “Neonicotinoid seed treatments: Effective crop protectants—or unnecessary, with potential collateral damage to bees?”

  1. Are any Extension folks involved in these studies or surveys? With such an obvious disconnect between academics and farmers, it would be useful to know what Extension Specialists and Educators who work directly with farmers have to say, even if it is just anecdotal.

    • Thanks for your thoughtful comments Alokin. I asked Krupke if he talks with farmers about these issues and what types of reactions he gets. He said: “My primary appointment is in extension here at Purdue, which means that I speak with hundreds of farmers each year. I always conclude my presentations by asking them to contact me if they have heavy infestations of the target pests, because I would like to work in the highest-pressure fields. I have not had any takers so far. The ones that speak to me at these events are uniformly happy to receive the information, they are surprised at the lack of yield benefits though. They are also always taken aback when I mention that EPA does not require efficacy to approve a registration. I have not encountered skepticism from farmers, but a lot of curiosity and interest.”

      • …they are surprised at the lack of yield benefits though.

        I wonder if that is because their experience has been to the contrary or if they truly think they are getting a benefit when they are not.

        They are also always taken aback when I mention that EPA does not require efficacy to approve a registration.

        This certainly has not been my experience in California. All of the growers I know understand this point and put a lot of trust in independent efficacy studies, particularly those done by UC Extension. A lot of value is also placed in relationships with both independent PCAs and those from ag chem retail; make a sale based on bogus information and that is probably the last one you make.

        I would be very surprised if farmers in bean country are any less skeptical of ag chem sales pitches than we are out here. What rings true to me are comments like those from Van Larson in this article who was burned once and recommends seed treatment with a full understanding of what he is doing and why.

    • I was thinking the same thing, but then I read the cited corn study and found that seed treatment dust generated during planting may be a potential route of exposure. Also runoff during rain events seems plausible.

      The corn study looked at potential for bee exposure during planting, it did not characterize actual bee exposure, so it is hardly a definitive study.

      If dust and runoff are significant factors, seems like those are things that could be easily mitigated.

      • I know there has been a few accidents with NN that didn’t stick on the seeds and coursed a poisonous cloud. That doesn’t explain how “CCD” could happen all over the world! In Holland the concentrations of NN in the water around the glasshouses were far too high. But all that doesn’t explain how CCD has been seen in areas where none NN was used and how bees survived in areas where ervery farmes used NN. In the beginning the American bee-expert Dennis van Engelsdorf thought NN was responsable for that. After examening all the reliable facts he changed his mind.

          • First Greenpeace called NN simply bee-poison. As it was proven wrong, they called NN insect-poison and a little later bird-poison. It’s the hate against pesticides in front the modern pesticides like NN. A lot off scientists wrote Greenpeace to stop with spreading false facts about bee losses and pesticides.

          • I would not lump the work of credible research scientists from respected institutions in with anything Greenpeace has to say on the subject. Neonics are insecticides, after all, so some effect on non-target species should be expected and dealt with.

          • Credible research? Look on internet ‘bee-gate’ and read how secret funds were created to pay corrupt scientist for their job. Or: The crises-of-integrity-deficient-science-paul driessen-townhall. I’ve studied hundreds of bee-studies and together with all the honest scientist I can tell you that Greenpeace misled the world and people who defend this scientific fraude are accompliced. The main course for CCD always has been varroadestructor in combination with bees which wern’t able to defend themselves.

          • I don’t see where any of the activist scientists named in Bee-Gate have contributed to this article or these claims. You ought to be careful about throwing too large a conspiracy net and oversimplify the subject lest you hurt your own credibility.

      • These compounds are water soluble less than 20% of the toxin is absorbed by the plant with the treated seeds, the rest of it runs off and contaminates ground and surface water this problem cannot be mitigated.

        • I am familiar with strategies used to mitigate nitrate pollution of groundwater in California. Same concept. Mitigation measures include modified irrigation strategies, timing of application, amount applied, how applied, type of nitrogen fertilizer applied. Also ways to mitigate nitrate runoff to streams. Point is, there are ways to mitigate such risks.

  2. In the discussion if neonics could harm bees, no one who blames NN for that, can explain how NN could get into the bees; They don’t dig up the seeds; they don’t swim in the water; they don’t eat from the plants; and in nectar and honey the highest levels ever found (and very rare) in nature were 0.000.006 gram per liter 2016. In 2015 only 3 nanogram. Bees fed with even higher amounts had no problems with them. According to NN-Opponent and toxicologist Lautier the deadly dosis is 3 nanogram per bee. It means that one single bee should eat 500 cc poisenend nectar or honey or 1000 cc in 2015 to die of theat. CCD has been seen in regions where none NN was used; Old bee-keeper families which have there bee-hives for generations, and live in the middel of agrigarian zones with a lot of NN used, had no CCD problems. The problem is clear: worldwide beekeepers started with ennobled bees which lost there ability to defend themselves against varroa-destructor. At the time the bee was bitten by the mites these parasites infect them with VDV-1, after weakened by beebloodlosses they become an easy prey for more viren as there are DWV Deformed Wing Viren, APLV, TRSV. It’s as simple as that !

    • Well, I don’t know that it is as simple as that, but the extent to which seed treatments are used as “insurance” depends on a risk-benefit analysis. I get the sense that risks of neonics are being exaggerated by many and therefore, those same people tend to minimize the relative value of prophylactic treatments.

      Also, a core principle of IPM is don’t apply a chemical unless you absolutely have to. That’s usually a pretty good rule to follow, but for some, it becomes don’t-spray-until-you-see-the-whites-of-their-eyes dogma. Depending on potential for loss, history, environmental impact, health and safety issues, and cost of intervention, pesticide application may be justified even when the pest is not present.

      • A few questions NN opponents cannot answer: How could CCD took place even in areas where nowhere NN has been used? How is it possible that bee-hives survive in the middle of NN-using farmers? How should the deadly dosis of NN got into all the bees, all over the world? Many people have no idea how modern pestcides work, are afraid of pesticides or have been made scared for them, thanks Greenpeace anti-pesticides campaign. Çommon people don’t know every plant has his weapons to defend himself against over eating or eatened before the seeds are mature. So they protect themselves for destinction; these are anti-nutrients or pesticides ! The coffeeplant uses the pesticide called coffein.

    • “They don’t dig up the seeds; they don’t swim in the water; they don’t eat from the plants”. They don’t have to dig up the seeds, no they don’t swim in the contaminated water they drink it. Yes they eat from the plants it’s called nectar and pollen. The effects of neonicotinoids are accumulative and irreversible so all these numbers your throwing around mean nothing!
      “The highest levels ever found (and very rare) in nature were 0.000.006 gram per liter 2016. In 2015 only 3 nanogram”. This statement doesn’t make sense either it all depends when you sample where you sample and what you sample. Are you talking about contaminated nectar, pollen, water, or planter dust?

      • When systemic NN is used correctly its not available for bees. At harvest time it should be vanished completely, otherwise people cannot eat them either. In studies the Dutch governement payd bees fed with those levels of 5 ng/l had no problems with that. After a couple of hours not one molecule could be found. Even with super-un-natural levels of 20 and 50 ng/l there were no problems! Don’t forget that bees onlt live for 21 days and there’s no time for accumulation to reach the deadly dosis of 5 ng per bee! Therefor they should eat 500 CC or 1000 CC highly contaminated honey or nectar. The worldwide enobled bees gather lots of honey but lost their ability to defend themselves against varroa destructor. Thats the vector of all the problems! Give it up Bill: Accept that you’ve been deceived by Greeneace & Co

  3. Correct me if I am wrong (please) but aren’t corn crops mainly pollinated by wind dispersion of pollen, not by insect pollination? I don’t really know what bees would be doing in a corn field. As a matter of fact, wheat, rice, soybeans and sorghum also are not pollinated by insects but by wind dispersion. I know this article is not about the role of neonics in bee die-off, it’s about the efficacy and necessity of neonics in maintaining or increasing the yields of these crops. But there apparently always seems to be a need to connect neonics with the bee issue, something that plays into the hands of anti-neonics fanatics in the world.

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