David's blog posts for 2013

One more unto the breach; a look at Defra’s stance on neonicotinoids



On 27 March 2013, Defra released “An assessment of key evidence about neonicotinoids and bees”. They recently reiterated their conclusion that the ban was 'unnecessary and unjustified'. Defra’s chief scientist, Prof Ian Boyd, can be viewed on YouTube expounding the points made in their March document. I’d like to draw your attention to something which strikes me as very odd.

The report flags up three key studies that suggest there may be a strong link between exposure to neonicotinoids and bee ill-health. They then say that five field studies provide contradictory evidence, suggesting little or no impact of these pesticides on bees in the real world. The remainder of the document is a detailed critique of the three studies that did find a link – suggesting that they gave the bees unrealistic doses of pesticide, and that they were “lab” studies and so not representative of the real world (neither of which is true – all of the studies were performed largely or entirely outside, with free-flying bees - but that is for another day).

What I find extremely odd is that the five field studies are not subject to the same examination. Why on Earth not? If we are to weigh up the evidence, surely we should examine each study equally carefully? They are not mentioned again, although the document ultimately concludes that they were correct in their findings.

Let me fill in the gap, and provide a brief evaluation of these five documents, held up by Defra as “field studies in which bees were allowed to forage naturally in the presence of crops treated with neonicotinoids”:

1)      Blacquiere et al., (2012), Ecotoxicology 21: 973-992. There is no field study in this paper. It is a broad review of the subject, but presents no new data at all.

2)      Chauzat et al., (2009), Environmental Entomology 38: 514-523. This study examines mortality in 125 honeybee hives in France over three years, in relation to levels of pesticides found in their pollen, honey, and in the bees themselves. Low levels of imidacloprid were detected in the hives, but hive mortality was low, and imidacloprid exposure did not predict mortality. However, no experiment was conducted. There were no control nests, and we do not know if any nests were near treated crops. This study appears to be perfectly valid as far as it goes, but is not a good test of whether neonicotinoid pesticides harm bees.    

3)      Hecht-Rost S (2009) Eurofins-GAB GmBH. This is an industry report, presumably funded by an agrochemical company. It is not published in a scientific journal, and hence has not been subject to peer review. I cannot obtain a copy, so it is impossible to evaluate.

4)      Thompson H et al. (2013). This is also unpublished, and so has not been subject to peer review. It is a study conducted by Fera (the research wing of Defra) in which bumblebee colonies were placed next to an untreated, control field of oilseed rape, or next to fields treated with either imidacloprid or clothianidin. It is unreplicated – there was only one control field – and the nests by the control field were all exposed to neonicotiniods, so there were no longer any controls. In short, it was a disaster.

5)      Genersch E et al. (2010). Apidologie 41: 332-352. At a quick glance, this one looks quite good – similar to no. 2, but on a bigger scale. There is no controlled experiment, but they followed the fates of over 4,000 honeybee hives over time. They conclude that Varroa and other parasites are important in causing honeybee ill-health, but not pesticides. However, if you look a little deeper this is somewhat misleading. Only 210 of the colonies were actually screened for pesticides, while all were screened for Varroa. In their analysis of the impacts of pesticides, the authors sum exposure to all pesticides (including fungicides and herbicides), and then use this value to try to predict winter colony loss. This is a very odd analysis to do, since herbicides and fungicides mostly have very low toxicity to insects. Not surprisingly, they find no relationship between total pesticide exposure and colony death. They don’t actually perform ANY analysis of the impacts of the insecticides alone, or of neonicotinoids in particular. The study appears to have been funded by the agrochemical industry.

In summary, these five studies tell us almost nothing about the impacts of neonicotinoids on bees. There is not one successful experiment, with replication and proper controls, to be found amongst them. Two of the five aren’t actually published studies at all.

Compare this to the three key studies that Defra are at pains to dismiss. They are published in the best journals in the world (two in Science and one in Nature). They will have been through an excruciatingly tough peer review process. All three have good levels of replication, and proper controls. Which group of studies would you trust?

Have Defra actually read the five studies in which they place their faith? I'm not convinced that they have.

Dave Goulson's research lab website

Biggest bumblebee poisoning event in history



On 15 June, a landscaping company in Wilsonville, Oregon, decided to spray some lime trees with insecticide. The trees were in a parking lot, and had some aphids on them, so there was a risk that some cars might get little drops of sticky honeydew on them. Faced with such a dire threat to the future of humanity, it was only natural and reasonable that the company should blitz the trees with Dinotefuran, a type of neonicotinoid insecticide.

On 22 June, Saturday morning shoppers reported the car park to be blanketed in dead bumblebees; about 50,000 at the latest count. The trees were flowering, and bees love lime nectar. The dose of pesticide they received from the nectar was clearly enough to kill many of them almost instantly, for they fell dead beneath the trees, the biggest recorded bumblebee poisoning event in history. Perhaps many more staggered off to die elsewhere.

For me, this highlights the utter stupidity of allowing pesticides to be used for cosmetic purposes, in gardens and parks. Using pesticides in farming can be justified by the need to grow food efficiently; we all need to eat. But do we need to be able to pop to the local garden centre or supermarket and buy bottles of highly toxic compounds advertised for use on roses and other flowers? In towns, councils routinely spray herbicides and insecticides for no real purpose, other than to make the streets look a little tidier, or the grass in the park look a little greener (and a little more toxic).

Why don’t we ban pesticides in urban areas, and turn our cities into havens for wildlife?

Toronto has banned such chemicals within the city limits. The city hasn’t been over-run with pests. People still have pretty gardens, and grow healthy vegetables. The parks look just fine. If they can do it, why not the rest of us?

Back in Oregon, the Xerces Society, an organisation devoted to insect conservation, have attempted to enclose the poisoned limes with netting to keep bees out. But they are concerned that the poison may stay in the trees for years, since neonicotinoids are very long lasting, so they may poison bees for years to come.

One wonders how many similar incidents escape attention because the bees do not die in such an obvious place. “Wild bees are killed all the time in agricultural fields where nobody sees it happen,” said Mace Vaughan of the Xerces Society. “The fact that this happened in an urban area is probably the only reason it came to our attention.”

Isn’t it high time we stopped poisoning our bees?



The neonicotinoid saga continues



Yesterday saw publication of my review of the evidence for broader impacts of neonicotinoids on wildlife other than bees in the Journal of Applied Ecology. If you'd like to read it, please go to Goulson Lab publications page, scroll down, and click on the link to the pdf.

The key points are as follows:

1) Neonicotinoids are very widely used, and have extremely high toxicity to all insects and many crustaceans. They are commonly applied as a seed dressing to crops.

2) Most (<90%) of the active ingredient do NOT go into the crop, but get washed into the soil and ground water. They also leach into streams. Levels found in streams and California and the Netherlands commonly exceed lethal concentrations for aquatic wildlife. Data from UK waterways appear to be absent.

3) They have a half life in soil which commonly exceeds 3 years, meaning that they rapidly accumulate in soil if they are used annually. The effects of this on soil organisms and soil health are not understood.

4) Neonicotinoids have been found in field-margin vegetation, which is hardly surprising if they are accumulating in soils. Impacts of this on farmland wildlife such as butterfly caterpillars feeding on field margin vegetation have not been studied.

5) If dressed seeds are consumed by granivorous birds such as partridge, or by rodents such as voles, they need only eat a few seeds to recieve a lethal dose. During drilling, seed is inevitably spilled, but we do not know whether it is consumed by wildlife.

6) Evidence that neonicotinoid seed dressings actually increase yield is absent (or is not available for public scrutiny). Some US studies suggest that they have negligible benefit to farming. In short, modern farming practices do not seem to be EVIDENCE BASED, but are driven by marketing by the agrochemical industry.  

7) We seem to have forgotten all about Integrated Pest Management (IPM), an approach which emphasizes minimising pesticide use through monitoring of pest numbers, crop rotations, encouraging natural enemies etc... Instead we are simply using pesticides prophylactically.  

Although I supported the 2 year moratorium on use of neonics, which comes into effect in December 2013 (better than nothing), it is entirely unclear what it will achieve, or what will happen afterwards. Neonics will continue to be used extensively for non-flowering crops such as winter wheat. Even if we completely stopped using them they would be in soils for years to come. So any benefits from the partial moratorium will not be apparent in 2 years. In any case, there seems to be no plan to monitor the benefits, so if they did occur (which is unlikely) we wouldn't know.....

It is hard for most of us to make sense of what is going on here.....

 Dave Goulson's research lab website




Bumblebees on Springwatch



Ah, the perils of live TV. They say never work with animals or children, so I fear I am in trouble. Tomorrow I am appearing live on "Springwatch in the Afternoon", broadcast from deepest, darkest Wales (an RSPB reserve somewhere near Aberystwyth). I'll be ineptly trying to plug my new book, A Sting in the Tale, while catching and handling bumblebees, talking about bumblebees, building a nest site for bumblebees, and being rude about garden centre bedding plants (which are rubbish for bees - intensive breeding has left them without nectar or pollen, or so bizarrely deformed that insects can't fit into them any more). What could possibly go wrong? 3pm, tuesday 4th April. Enjoy :)

Dave Goulson's research lab website

Neonicotinoids and bees; what is the fuss all about?



When I was first asked to support a ban on neonicotinoid insecticides, I was very sceptical. I’d previously been asked to sign up for campaigns claiming that bee declines were due to mobile phones, GM crops, overhead power lines, and various other eccentric or implausible notions. However, a review of the science suggested that there was something worth investigating, and for the last two years I seem to have had time for little else.

The issue has focussed largely on harm these chemicals might be doing to bees, both domestic honeybees and wild pollinators such as bumblebees. I’ll focus on bumblebees here, for they are the subject of my particular expertise. Neonics are widely applied as a seed dressing to crops such as oilseed rape, and being systemic they spread through the plant tissues into the nectar and pollen. They are highly toxic to insects; for example the “LD50” (the dose that kills half of test subjects) in honeybees is about 4 billionths of a gram. To put that in context, 1 gram – little more than the weight of a sachet of salt – would provide an LD50 to 250 million honeybees, or roughly 50 metric tonnes of bee. They are neurotoxins, binding to neural receptors in the brain and causing swift paralysis and death.

Until recently, there had been few studies of neonics and bumblebees, all small scale and nearly all performed in cages or glasshouses. Taken together, they seemed to suggest that exposure to very low levels of these chemicals, such as might occur when a bee fed on a treated oilseed rape crop, was not sufficient to kill many bees, but it seemed to affect their behaviour, particularly their ability to learn, gather food, and navigate. These are not impacts that are assessed by any of the safety tests by which pesticides are judged (although there are plans to introduce such tests in Europe in the very near future). They are also impacts that are likely to be much more important in the field, when bees naturally perform astonishing feats of navigation and learning when gathering food from flowers. It seemed to me, and to a number of other researchers around the world, that there was a need to study what impacts these sublethal affects might have on bee colonies in natural situations.

To investigate this, we exposed bumblebee nests to the concentrations of neonics found in the pollen and nectar of oilseed rape for two weeks, and then placed the nests out in the field to see how they fared compared to control nests. Over the following 6 weeks the treated nests grew more slowly, and ultimately produced 85% fewer new queens. Since our study, work from other labs has confirmed that field-realistic doses greatly reduce pollen collection in bumblebee workers, potentially explaining why our treated nests performed poorly. It has also been found that concentrations of neonicotinoid as low as 1 part per billion (ppb) in their food cause a drop in egg laying in bumblebees of 30%. Considerably higher concentrations than this have been found in pollen of treated crops (the typical range in pollen is about 1-10 ppb, although 50 ppb has been found in lucerne pollen, and over 100 ppb in melon pollen).

For bumblebees, the evidence so far is convincing and coherent; exposure to levels of neonic commonly found in crops have profound impacts on colony success. The only study which apparently contradicts this was recently placed online by Defra, a report describing a study they conducted in 2012 in which they attempted to repeat our work but with the pesticide exposure phase of the experiment occurring in the field. They placed bumblebee nests next to the only untreated field of oilseed rape they could find, or next to one of two other fields treated with two different neonics, and they followed the colonies over time. Unfortunately they had no replication – just one field per treatment – and, disastrously but interestingly, the control nests all became contaminated with neonics. The summary of this report claims the study shows no clear effect of neonicotinoids on bumblebee colonies; hardly surprising, given the absence of any controls – and hardly the sort of convincing evidence one would wish government to base its policies upon. It is also not really true – in fact there was a highly significant negative relationship between neonicotinoid levels recorded in each nest and how well the nest performed, but the authors removed this relationship by “taking out outliers” – by which they mean removing the nests that received the highest exposure (which also happened to be the nests that performed most poorly) from their data set and then re-ran the tests.

Perhaps the most valuable lesson to be learned from this work is that bumblebee nests placed into the English landscape become contaminated with multiple types of neonic, even when on farms where none are used. Many of the nests had concentration of neonic higher than 1 part per billion, and most had detectable levels of at least two different neonics.  Bizarrely, the results suggest that bumblebees have a particular predilection for the neonic thiamethoxam, for the control bees seemed to have ignored the untreated rape field right next to their nests and flown a long way to find a thiamethoxam-treated crop.

While the debate has focussed heavily on bees so far, there are broader issues to consider. Neonics are very persistent in soils, and evidence has recently emerged that they accumulate over time; a study in East Anglia performed by Bayer in the 1990s found concentrations up to 60 parts per billion in soil after 6 years of annual use. This is likely to be enough to have profound impacts on soil life. It has also emerged that they get into field margin vegetation, and into streams and ponds. A concentration of just 0.6 parts per billion is enough to kill mayfly nymphs. It may be that, while focussing on bees, we have missed the bigger picture. 


The economics

A common argument in favour of neonics is that they provide huge economic benefits, and that the alternatives are worse. A glossy document produced by the “Humbolt Form” (funded exclusively by the agrochemical industry) in early 2013 claimed that a ban on neonicotinoids would cost the EU 17 billion Euros and 50,000 jobs. However, the hard evidence for these claims seemed to be lacking. Indeed, the evidence that neonicotinoids are important for crop production is surprisingly difficult to find. Studies from USA show that yields of soya bean do not benefit at all from neonic seed dressing, despite their application being standard practice. Sadly, similar experiments in the UK have not been conducted. Since farmers get most of their agronomic advice from companies that supply pesticides, it is reasonable to suppose that a good proportion of UK pesticide use may be unnecessary.


Whatever happened to IPM?

When I was at University in the 1980’s, I read Rachel Carson’s Silent Spring, and was taught about the terrible mistakes made in agriculture in the 1950s and 1960s when indiscriminate use of persistent, broad-spectrum insecticides, and an abandonment of traditional cropping practices such as rotations led to huge pest outbreaks. The pest insects had all become resistant, while their natural enemies had largely been eradicated. As a result, an approach called Integrated Pest Management (IPM) had been developed, and we were taught that this was the future of pest control. IPM is predicated on minimising pesticide use: farmers monitor their crop pests, and only take action when necessary; they encourage natural enemies as far as possible, use crop rotations and other cultural controls to suppress pests, and only use the insecticides as a last resort. Even then, they avoid those that persist in the environment.

Whatever happened to this philosophy? Why are we now applying pesticides prophylactically to more or less all crops? Did we learn nothing from our past mistakes?  


The politics

The EFSA spent 6 months evaluating all the evidence, and concluded that current use of neonics poses unacceptable risks to bees. The UK’s Environmental Audit Committee (a group of MPs) agreed. Numerous NGO’s, including the RSPB, who are normally very cautious, also agree. Even the WI support a ban. What was once a radical stance is now where the vast majority of informed opinion lies; on 29 April the EU member states voted for a 2 year moratorium on use of the three most-commonly used neonics on crops visited by bees.

The UK voted against the ban, with Chief Scientific Advisor Sir Mark Walport saying that everyone else had misinterpreted the evidence. He also argued that applying the precautionary principle would lead us to continue using neonicotinoids, an argument that few of us could follow.


What Next?

The moratorium is only for two years, yet we have clear evidence that it will take far longer than this for neonicotinoids that have accumulated in soils to break down. In any case, they are still being widely used, on winter wheat for example, and some types of neonic are not included in the ban.  So it is unlikely that we will see the benefits of the moratorium in rebounding bee populations any time soon. In any case, there seems to be no plan to actually monitor bee populations, so even if they did recover it is not clear how we would know.

What will farmers do without neonics? It is hard to say. It would be nice if they returned to an IPM approach, but with their main / only source of advice being from people with a vested interest in selling chemicals, this seems unlikely. 


Have we solved the bees’ problems?

I’m afraid the answer is an emphatic NO. Bees have been declining for many decades, and much of their decline has been due to loss of flower-rich habitat, which has been exacerbated by the arrival of non-native diseases, and by widespread use of pesticides. We have taken a step to reduce (but not remove) their exposure to some brands of one type of pesticide, for two years. That is nowhere near enough. If we want to ensure healthy populations of honeybees, bumblebees, and other wild pollinating insects upon which we depend for our crop production, and more generally if we wish to support the healthy, diverse ecosystems upon which our future health and wellbeing depends, then we need to find ways to produce food in a sustainable way which incorporates the needs of biodiversity. At present we are failing to do this.


Dave Goulson's research lab website