Link between neonics and bee declines “very clear”

Honeybee worker with radio-frequency identification tag – Photo: Amro Zayed/York University/Science

York study takes on ‘controversy’ over honey bee declines and pesticide use

By KATE ALLEN Toronto Star

A major new study conducted in Ontario and Quebec corn fields has found that neonicotinoids, a widely-used and controversial class of pesticides, hurt the health of honey bees, and comes as provincial, federal, and international regulators wrestle with reining in the use of these agrochemicals.

The Canadian research, led by biologists at York University, is published in the journal Science along with another ambitious study conducted in European fields. Together, they address a major gap.

“They are putting these bees into landscapes where farmers are really farming,” says Professor Nigel Raine, Rebanks family chair in pollinator conservation at the University of Guelph, who was not involved in the research. “The key message that’s coming out of both of them is that they found impacts on honey bee colonies. Previously that has not been found in the field, and that has been a source of confusion.”

Both honey bees and wild bees have suffered dramatic declines in recent decades. Bees are critically important pollinators for many crops and most wild flowering plants; estimates of the benefits they provide humans through these “ecosystem services” is measured in the tens of billions of dollars.

Lab experiments have shown that neonicotinoids — the most widely-used class of insecticide worldwide — have negative effects on bee life spans, foraging behaviour, the production of new queen bees, and other measures of health. But evidence from the real world has been scant and conflicting. Bees are beset by environmental ills, from climate change to loss of habitat.

“That’s where the controversy lies,” says Christy Morrissey, an ecotoxicologist at the University of Saskatchewan. “If you look at the lab studies, they’re highly conclusive. Neonicotinoids have a range of affects on all sorts of organisms, both honey bees and wild bees included. But when you start moving out into the field, you get messier responses.”

The two new studies sought to rectify this.

The Canadian group, led by York University’s Amro Zayed, studied five apiaries close to corn fields — four in Ontario and one in Quebec — and in six apiaries located far from agriculture, most in urban settings like Toronto and London. The researchers returned to 55 colonies across the 11 sites throughout the planting season, collecting dead and live bees, larvae, pollen and nectar.

The team found neonicotinoids in all the different types of samples from the sites near corn, especially in the pollen, and found them all throughout the growing season, a period of nearly four months. But most of the pollen brought back by the bees wasn’t coming from the treated corn or soy — it was coming from native plants surrounding the fields.

The next year, Zayed’s lab took honey bees housed at York’s research apiary and fed them pollen dosed with the “field realistic” levels of neonicotinoids they had observed the previous season. The exposed bees had life spans reduced by 23 per cent, were less likely to identify and remove diseased larvae, and were more likely to lose their queen. These combined effects can cause a colony to deteriorate.

Researchers also found that the toxicity of neonicotinoids nearly doubled when honey bees were exposed to them along with a commonly used fungicide, boscalid, which on its own did not affect the bees.

“You get a prescription from your doctor and there is a list of other medications you shouldn’t take,” says Zayed by way of comparison. “We go from bad — neonicotinoids on their own — to worse — neonicotinoids with the fungicide.”

The European study looked at how three bee species fared — the honey bee, bumble bee, and solitary bee — near 33 oilseed rape crops in Germany, Hungary, and the U.K.

The team found varied outcomes. Honey bees in Hungary exposed to one type of neonicotinoid were less likely to survive the winter, but in Germany fared fine. Bumblebees exposed to high levels produced fewer queens, while solitary bees produced fewer eggs. The geographic context seemed to play a role in what effects were observed, but most effects were negative.

Some critics called the European study “inconsistent.” But more praised the study, saying that variation is what you would expect in nature.

The EU placed a moratorium on the use of neonicotinoids in 2013 because of concern over the risks to bees and is weighing a total ban, which France has already announced.

In Ontario, nearly 100 per cent of corn seed and 60 per cent of soybean seed are sold pre-treated with neonicotinoids. Two years ago the province became the first jurisdiction in North America to curb the number of corn and soy field acres planted with neonicotinoid-treated seeds, aiming for an 80 per cent reduction by 2017. In 2016 the province reported a 24 per cent drop from 2014, well short of the target.

Health Canada’s Pest Management Regulatory Agency published a preliminary risk assessment on one neonicotinoid, imidacloprid, in January 2016 and found that it did not present an unacceptable risk to bees. Later that year, it did find risks to aquatic environments, and proposed phasing the agrochemical out over three to five years. Special reviews of two other neonicotinoids are underway.

“These are both very strong papers and will certainly have an impact,” says Morrissey.

“We think we’ve made that link between neonicotinoid exposure and declines in bee health very clear,” says Zayed.

“Yes, honey bees are exposed to sublethal doses of neonicotinoids for a long period of time, and that exposure has negative effects on bees.”

Pesticides damage survival of bee colonies, landmark study shows

By Damian Carrington The Guardian June 28 2017

The world’s largest ever field trial demonstrates widely used insecticides harm both honeybees and wild bees, increasing calls for a ban

Widely used insecticides damage the survival of honeybee colonies, the world’s largest ever field trial has shown for the first time, as well as harming wild bees.

The farm-based research, along with a second new study, also suggests widespread contamination of entire landscapes and a toxic “cocktail effect” from multiple pesticides.

The landmark work provides the most important evidence yet for regulators around the world considering action against neonicotinoids, including in the EU where a total ban is poised to be implemented this autumn. The insecticides are currently banned on flowering crops in the EU.

The negative impacts found varied across different countries, leading the pesticide manufacturers to question whether the results of the research, which they funded, were real. The new research is published in the prestigious peer-review journal Science.

Neonicotinoids represent a quarter of the multi-billion dollar pesticide market but have been repeatedly linked to serious harm in bees in lab-based studies. Bees and other pollinators are vital to food production but are in decline, in part due to loss of habitats and disease. But there had been few realistic field studies to date to address the role of the insecticides and only occasional evidence for colony-level harm in wild bees.

The new research took place at 33 large farmland sites spread across the UK, Germany and Hungary. Honeybees, bumblebees and solitary bees living by insecticide-treated fields of oil seed rape were compared with those in fields where insecticides were not used in the year of the study.

The survival of honeybee colonies was reduced by exposure to the insecticides in the UK and Hungary, but not in Germany, where the bees foraged far less on oil seed rape and had lower levels of disease. The reproductive success of the wild bees was cut as the insecticide exposure increased in all three countries.

“We showed significant negative effects at critical life cycle stages,” said Prof Richard Pywell, from the UK’s Centre for Ecology and Hydrology (CEH), and part of the research team. “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.”

Scientists not involved in the research backed the conclusions. “Together, the two studies make strong contributions to the growing scientific consensus about the harms of neonicotinoid pesticides to bees,” said Prof James Nieh, at the University of California San Diego. Addressing the differences between countries, Prof Jeremy Kerr, at the University of Ottawa in Canada, said: “Neonicotinoid applications are a kind of reproductive roulette for bees. Depending on local environmental characteristics, they can materially reduce survival prospects.”

The $3m cost of the research was met by Syngenta and Bayer, the companies that sell the two neonicotinoids tested, as part of a voluntary commitment to increase the available field data. But the companies were not involved in the designing, conducting or reporting of the study.

It found that the bees in Germany got just 15% of their food from the oil seed rape fields, compared to 40-50% in the UK and Hungary. “Clearly the bees in Germany are feeding on other flower resources in the landscape and are less exposed to neonics,” said Pywell.

The scientists also discovered that the wild bees were exposed to a neonicotinoid that was not even used in the trial and concluded the harm caused may result from “persistent residues in arable systems due to their widespread and often very frequent use”.

However, both Bayer and Syngenta expressed doubt about the “simplistic” interpretation of complex and “inconsistent” results. “We do not share CEH’s interpretation and remain confident that neonicotinoids are safe when used responsibly” said Richard Schmuck, director of environmental safety at Bayer CropScience.

Peter Campbell, from Syngenta, said: “The negative and positive results reported by CEH could easily be random, ie not real.” He said even taking the results at face value “demonstrates that neonics can be used safely or even with benefit to bees under certain circumstances, such as reported in Germany.”

But CEH’s Pywell said: “We stand by our peer-reviewed paper. We undertook the statistical analysis and reported the findings as we saw them and those are underpinned by the data. We are absolutely independent.”

The second new study published in Science, carried out on corn farms in Canada, also found crops were not the main source of neonicotinoids to which bees were exposed. Instead, the contaminated pollen came from wildflowers, as has been shown recently in the UK.

“This indicates that neonicotinoids, which are water soluble, spill over from fields into the surrounding environment, where they are taken up by other plants that are very attractive to bees,” said Nadia Tsvetkov, at York University in Canada and who led the research.

“The detection of the potential long-term persistence of neonicotinoids in the soil by both studies raises the spectre of a reprise of Rachel Carson’s Silent Spring,” said Prof Robert Paxton at Martin-Luther-University Halle-Wittenberg in Germany.

The Canadian research also found that the presence of realistic levels of a fungicide made the neonicotinoids twice as toxic to bees. “The effect of neonicotinoids on honey bees quickly turns from bad to worse when you add the fungicide boscalid to the mix,” said Prof Valérie Fournier, at Laval University in Canada and also part of the team. Pesticides are not tested in combination by regulators and Kerr said: “This study shows that mixtures matter.”

Environmental campaigners said the new research exposed the full impact of neonicotinoids. “The horror story is clear: we have contaminated our land and water with persistent neonicotinoid pesticides,” said Matt Shardlow, CEO of the charity Buglife.

“This major study marks a watershed moment in the fight to protect our bees [and] fills a crucial gap in our scientific understanding,” said Greenpeace UK’s chief scientist Doug Parr. “The case for a permanent ban on these pesticides is now unassailable, and our politicians will have to take action.”

But Guy Smith, from the National Farmers Union in Britain said neonicotinoids were important in protecting crops and producing food: “We strongly believe that policy decisions – such as restricting the use of neonicotinoids – must be based on sound science which gives strong evidence. And while this CEH study provides more useful information, we still don’t have that definitive evidence for the impact of neonicotinoids.”

Prof David Goulson, a bee expert at the University of Sussex, UK, said: “In the light of these new studies, continuing to claim that use of neonicotinoids in farming does not harm bees is no longer a tenable position. In my view we should also consider the bigger picture; the current model of farming based on huge monocultures treated with dozens of pesticides is causing devastating environmental harm, undermining vital ecosystem services that keep us all alive.”