Skip to content
Are Neonics Killing Bees? the Largest Ever Field Study Brings Conflicting Views on Neonics and Bees

Are Neonics Killing Bees? the Largest Ever Field Study Brings Conflicting Views on Neonics and Bees


In late June, the results of the largest ever field study into the effects of neonics on bees were published in the premier peer-reviewed journal Science. Framed as a watershed moment by many, the paper is likely to pressure the European Commission towards a total ban on the widely used insecticides, with a partial moratorium already in place.

Nonetheless, the findings were far from cut and dry. Interpretations have varied, with divisions across media commentators and the scientific community. Most controversially, the scientific research team and industry research funders are at loggerheads, with the independent study funded by two of the world’s biggest manufacturers of the pesticide – namely, Syngenta and Bayer Crop Science. A second recent study looking at the pesticide in Canadian cornfields may, however, lend support to the case against the chemical. 

The European Neonics study results

Conducted over at 33 farmland sites across the UK, Hungary and Germany, the landmark study on neonics has been years in the making and much anticipated by etymologists, farmers and the agrichemicals industry. Otherwise known as neonicotinoids, neonics are a family of insecticides used to protect crops against sap-drinking insects like aphids by targeting their central nervous system. First developed for market use by Shell in the 1980s, farmers favoured the chemical as it came already coated on bought seeds, removing the need for spraying. The active toxin will permeate the plant’s whole tissue, spreading through stems, leaves, flowers, pollen and nectar.

Because of the persistence of the toxin in farmland soils, the chemical has long been a concern among environmentalist groups, who have warned of a ‘scattershot’ effect on non-pestilent insects. In 2013, the EU placed a partial ban on three neonics (imidacloprid, clothianidin and thiamethoxam) after concluding there was too great a risk to justify their continued use. Earlier this year, the Guardian reported a blanket ban may be impending. In contrast, the United States has no current restrictions on neonics, though the Environmental Protection Agency (EPA) has set up a review schedule for risk assessment in 2018.

In the study, scientists compared bee health in colonies foraging on large adjacent canola fields (canola being a derivative of rapeseed, a popular crop for farmers and food source for bees). The first field was treated with one of two banned neonics (either clothianidin or thiamethoxam) and a fungicide, whereas the second contained crops treated with just fungicides.

In the UK and Hungary, bees exposed to the neonics were shown to suffer, with a higher colony loss over the winter and difficulties reproducing. For bees in German farmlands however, the results were flipped. Colonies gathering food from neonic-treated fields actually fared better than their counterparts in the adjacent fields, with greater reproductive success.

Despite the conflicting results, the study’s authors nonetheless drew a negative relationship between neonicotinoid use in agriculture and the health of both honey bees and wild bees.

“We showed significant negative effects at critical life cycle stages,” said Professor Richard Pywell from the UK’s Centre for Ecology and Hydrology (CEH), the research group behind the study. “If the bees are foraging a lot on oil seed rape, they are clearly at risk. This is a large and important piece of evidence, but it is not the only evidence regulators will look at.”

The case of Germany

How to explain the German case then? The researchers offered several explanations.

Firstly, the diet of honey bees in Germany was more varied. Where colonies in the UK and Hungary got 40-50% of their food from the treated canola fields, German bees foraged more broadly, supping on canola only 10% of the time. The UK bees had few menu alternatives, suggested Pywell, as modern farming in the region has limited the available spring flowers. And in Hungary, the canola fields stretched over larger acreages, meaning it would’ve been too far a journey for the bees to search for many alternative food sources beyond the perimeter.

Pywell also pointed out that German bees are generally better set up for healthy living, with fewer parasites affecting the nation’s hives. Exposure to neonics may therefore only take significant effect if the insects’ immune systems are a) made vulnerable by disease and b) weakened by a non-diverse diet. 

The view from some scientists

Joining environmental activists like Greenpeace and publications like Nature, New Scientist and the Guardian, a throng of scientists have stood in support with the researchers, seeing the paper as a vindicating blow against the agrichemical industry.

“I think you’d have to be pretty unreasonable at this point not to accept that, at least some of the time, these chemicals harm bees when used in normal farming practice,” said Dave Goulson, a Biology Professor at University of Sussex, UK.

Jeremy Kerr, from the University of Ottawa in Canada, describes neonics as “a kind of reproductive roulette for bees” to explain the study’s discrepant results. “Depending on local environmental characteristics, they can materially reduce survival prospects.”

Kerr himself was part of a separate research team which investigated the relationship between pesticides and bees. This second paper, also published recently in Science, adds weight to the findings of the first. Carried out by Canadian researchers looking at neonics in cornfields, it found that the water-soluble pesticide is spreading into wildflowers outside of cultivated lands.

The paper also revealed that the presence of fungicides can exacerbate the effects of neonic toxins. Typically, regulators only consider the effects of pesticide chemicals in isolation. “This study shows that mixtures matter,” said Kerr.

The view from Syngenta and Bayer

While the design, execution and reporting of the study was carried out independently, the US$3 million cost of research was footed by Syngenta and Bayer. With neonics making up a quarter of the multi-billion dollar pesticide market, both companies have rejected CEH’s conclusions, with Syngenta representative Peter Campbell dismissing the data as “easily random, i.e. not real.”

“We do not share CEH’s interpretation and remain confident that neonicotinoids are safe when used responsibly,” concurred Richard Schmuck, director of environmental safety at Bayer Crop Science. (Who, we have to add, has a very unfortunate last name.) 

The view from critical media

Several publications also query the interpretation put forward by researchers and largely echoed by the media. “The results were not as clear-cut as experts had hoped,” mused the Washington Post. “The differences between bees in treated or untreated fields were largely insignificant, and many of the bees in both groups died before they could be counted.”

American news and culture journal Slate mounted the most forthright challenge, accusing the researchers’ claims as being overblown and selective. According to the article’s author Jon Entine, though the data is sound and valid, the way the paper has been written makes it into little more than an ideological tool to add momentum to anti-chemical lobbying agendas. Only a few data points indicate that neonics have a negative effect, he argued, and almost as many show a positive effect.

“Sweeping statements about the continuing beepocalypse and the deadly dangers to bees from pesticides, and neonicotinoids in particular, are irresponsible,” Entine finished scathingly. “That’s on both the scientists, and the media.”

By Kate Prendergast

General Question About Neonics killing Bees

1. What are neonicotinoids, and why are they used in agriculture?

Neonicotinoids, often referred to as neonics, are a class of insecticides used to protect crops from sap-drinking insects like aphids. They work by targeting the central nervous system of insects, leading to paralysis and death. Neonics are popular among farmers because they can be applied as a seed coating, which reduces the need for spraying and allows the toxin to permeate the entire plant, providing long-lasting protection.

2. What were the main findings of the largest ever field study on neonics and bees?

The largest field study on neonics, conducted across the UK, Hungary, and Germany, found that bees exposed to neonic-treated fields in the UK and Hungary suffered higher colony losses and reproductive difficulties. However, in Germany, bees foraging in neonic-treated fields fared better than those in untreated fields. Despite these mixed results, the study's authors concluded that neonicotinoids negatively affect bee health, particularly during critical life stages.

3. Why were the results of the study on neonics and bees different in Germany compared to the UK and Hungary?

The differing results in Germany were attributed to several factors. German bees had a more varied diet, foraging less on treated canola fields compared to bees in the UK and Hungary. Additionally, German bees were generally healthier with fewer parasites. This suggests that bees' exposure to neonics may have more significant negative effects if their immune systems are already compromised by disease or a non-diverse diet.

View PDF

Previous article The Complete Guide to Beehive Frames: Types, Dimensions, and Maintenance

Leave a comment

Comments must be approved before appearing

* Required fields