David's blog posts for 2017

Pesticides in “Bee-Friendly” flowers

Jun

01

Take a walk around your local garden centre and you will see a mouth-watering display of gorgeous plants on display. You might note that some are specifically labelled as bee or pollinator friendly, with a picture of a cartoon bumblebee on the label. The Royal Horticultural Society (RHS) provide a “Perfect for Pollinators” logo which can be added to the label of any of the long list of garden plants that they judge to be good for pollinators. If you like hearing the buzz of bees in your garden, and want to do your bit to help our wildlife, you might well be tempted. Indeed, I have often spent a small fortune myself on potted plants when I only went to the garden centre to buy a pack of vegetable seeds. The big DIY and supermarket chains are similar – somewhere by the main entrance you will see a range of colourful plants in plastic pots and trays, some of them labelled as bee-friendly.

            If, like me, you’ve ever succumbed to the temptation to buy these plants, you may be somewhat concerned by the results of our latest research. Here at Sussex University we have been busy screening the leaves, pollen and nectar of these plants to see if they contain pesticides. We bought flowering plants from a range of major outlets; Wyevale (the biggest garden centre chain in the UK) and also Aldi, B&Q and Homebase. We deliberately bought plants that are known to be attractive to bees and butterflies; most of them had a bee-friendly logo, often the RHS one.

We found that most of these plants contained a cocktail of pesticides, usually a mixture of fungicides and insecticides. I wish I could say that I was surprised by the results, but sadly I wasn’t, for this mirrors similar studies performed in other countries. Only two out of 29 plants contained no pesticides. Seventy six percent of them (22/29) contained at least one insecticide, and 38% contained two or more insecticides. One flowering heather plant contained five different insecticides and five different fungicides – a veritable toxic bouquet. Seventy percent of the plants contained neonicotinoids (insecticides that are notorious for their harmful effects on bees), commonly including the ones banned for use on flowering crops by the EU (for the technically minded, 38% contained imidacloprid, 14% contained thiamethoxam and one contained clothianidin). Enough detail; you get the picture. Plants sold as ‘bee-friendly’ plants are usually stuffed full of pesticides.

Just before our results went public, B&Q (who knew that out study was appearing imminently) announced that they were prohibiting their suppliers from using neonicotinoids on their plants from February 2018. This is of course a great step forwards; well done B&Q, next time I need some screws or shelving I will be heading your way, and I hope others do likewise. Once our results were out Aldi declared that they stopped using neonicotinoids in October 2016 (we bought the plants we tested from them in July 2016). Also great news.  

Homebase and Wyevale have so far declined to make any public comment, despite high profile articles about the work in the Daily Mail and Independent. The Horticultural Trades Association, which represents the gardening industry, has been less than positive (http://bit.ly/2rXM4sL). Firstly, they claim that the three neonicotinoids banned by the EU on flowering crops are not used in horticulture (which would seem to simply be untrue). They then go on to say the “industry works closely with government bodies and other stakeholders to uphold high standards of environmental management”. They say that the concentrations of pesticides we found are at “low levels”, that we only sampled from “a very restricted area of the country”, and they suggest that the presence of clothianidin in one plant shows that our samples were contaminated, since this product has never been approved for use on ornamentals. In other words, instead of engaging positively, they try to undermine and play down our work.

Let’s have a closer look at their criticisms. Firstly, the concentration of the pesticide is of course important. Modern analytical techniques are very sensitive and tiny concentrations can be detected. Perhaps the concentrations we detected are all too low to do any actual harm? For neonicotinoids, the concentrations typically found in the nectar and pollen of treated crops such as oilseed rape are in the range 1-10 parts per billion (ppb). Exposure to such concentrations has been found to impair bee navigation and learning, reduce egg laying, lower sperm viability, and suppress the immune system. In a study with bumblebee nests we found that giving them pollen with 6ppb of neonicotinoid reduced nest growth and resulted in an 85% drop in the number of new queens produced[1]. In the ornamental flowers, we found imidacloprid at up to a maximum concentration of 29ppb, clothianidin at 13ppb and thiamethoxam at 119ppb. In other words, concentrations far higher than those known to harm bees. The claim that we only sampled from a “very restricted area” is pretty absurd. It is true, we sampled from stores near Brighton, but these are huge chains with a national/international supply network. Are HTA really suggesting the problem is peculiar to East Sussex? On the presence of clothianidin and the suggestion that our samples were contaminated, HTA need to learn a bit more about pesticides. As well as being used as a pesticide in its own right, clothianidin is a breakdown product of the closely related chemical thiamethoxam. The Ageratum plant containing the clothianidin also contained much higher levels of thiamethoxam, presumably the product with which it had been treated. So, not evidence of contamination at all.          

            I would argue that, by quibbling over details and focussing on neonicotinoids, HTA are missing the bigger picture, as indeed are B&Q and Aldi. Neonicotinoids are undoubtedly bad for bees, but what about all the other chemicals? If I buy a plant to feed to bees I don’t want it to have been drenched with a pyrethroid or organophosphate insecticide either. Both are highly poisonous to bees (and organophosphates are exceedingly toxic to people too). Even some of the fungicides have been found to harm bees[2]. If I’m buying plants to encourage wildlife, I don’t want the lingering worry that I might be accidentally poisoning my bees, hoverflies and butterflies. I don’t use any pesticides in my garden – I simply don’t need them. I don’t want to bring them in accidentally.   

            It is a shame that the horticulture industry seems largely unwilling to engage over this issue. It is perhaps not surprising, since their track record is not great. They’ve been continuing to promote and use peat-based composts for many decades despite the ready availability of perfectly good alternatives (in case you didn’t know, peat extraction does terrible damage to peat bogs, exacerbates flooding and ultimately releases huge amounts of carbon dioxide into the atmosphere). With birds, bees and butterflies all in rapid decline (2016 was the worst year ever for British butterflies), we all need to be willing to admit our mistakes and change our ways. HTA and the big garden chains such as Wyevale could really help to make a difference if they wanted to. I’d be very happy to help if they would like some advice (Wyevale, how about launching a new organic range of genuinely bee-friendly plants?)

Until the gardening industry gets its act together, I’d suggest the following. If you must buy plants, buy from an organic nursery, or failing that from B&Q or Aldi. Better still grow them from seeds, or if you haven’t the patience, plant swap with your friends and neighbours (if anyone wants some comfrey roots and lives near E Sussex I’d be happy to give you some, pesticide free, it is a fabulous plant for bees). We really can make our gardens into havens for wildlife, but not by driving to the garden centre to buy pesticide-laced plants grown in peat-based compost inside disposable plastic pots.    

 -----------------------------

Our research describing in detail the pesticides we found is here: http://www.sciencedirect.com/science/article/pii/S0269749117305158 

It was published in the journal Environmental Pollution, May 2017. 



[1] Whitehorn et al. 2012, Science, 336: 351-352.

[2] Bernauer et al. 2015, Insects 6: 478-488

Are neonicotinoids killing birds (part 2)

Mar

29

This article will make more sense if you read my previous blog first!

 

In a recent online article NFU’s Dr Chris Hartfield is quoted as saying:

“Dave Goulson’s theories about neonicotinoids poisoning birds are simply that – theories – and are not backed up by evidence from real life”, he added. In the UK, poisoning of all animals is investigated by the Wildlife Incident Investigation Scheme. If seed-eating farmland birds were being poisoned as a result of eating neonicotinoid treated seed, you would rightly expect this scheme to be finding these incidents. There are no incidents of bird poisoning resulting from the use of neonicotinoids over the last ten years. Promoting theories without the evidence to back them up is only going to damage the cause of pollinators and wildlife, and damage the public perception of science in general.

My detailed response to this was posted on 7 March. On that date I also contacted the wildlife incident unit. I asked them to tell me what pesticides they would test a dead bird for. The answer, kindly provided by David G Brown, is below:

“This can be quite specific depending on the evidence available but in general terms analysis will look for pesticide groups such as carbamates, organophosphates and rodenticides in addition to compounds such as chloralose and metaldehyde (slug pellets), the former a frequently abused product historically, the latter more commonly confirmed in ‘misuse’ incidents.”

So, there are no incidents of bird poisoning resulting from neonic use because dead birds aren’t normally tested for neonics in the UK. The apparent anomaly between France, where many dead birds contain neonics, and the UK, where no such incidents have been detected, is thus rather easily explained.  

Are neonicotinoids killing birds?

Mar

07

Philip Lymbery, chief executive of Compassion in World Farming, has just launched his new book “Dead Zone: Where the Wild Things Were.” In it, he suggests that neonicotinoid insecticides may be contributing to bird declines. This claim has come under heavy fire from NFU and the agrochemical industry. In a recent online article NFU’s Dr Chris Hartfield is quoted as saying:

Evidence from real life field situations did not back up the claims, which are based on research by Dave Goulson, Professor of biology at Sussex University. Professor Goulson has published a paper which claimed a grey partridge would be killed by eating five treated seeds, and a sparrow after two. He also said birds which ate insects were ‘declining more rapidly in areas which use neonics’.

            “Dave Goulson’s theories about neonicotinoids poisoning birds are simply that – theories – and are not backed up by evidence from real life”, he added. In the UK, poisoning of all animals is investigated by the Wildlife Incident Investigation Scheme. If seed-eating farmland birds were being poisoned as a result of eating neonicotinoid treated seed, you would rightly expect this scheme to be finding these incidents. There are no incidents of bird poisoning resulting from the use of neonicotinoids over the last ten years. Promoting theories without the evidence to back them up is only going to damage the cause of pollinators and wildlife, and damage the public perception of science in general.

The paper to which Dr Hartfield refers was a review I published in 2013 in Journal of Applied Ecology (Goulson 2013).  In it, I say the following:

Although neonicotinoids do show relatively low toxicity to vertebrates, we might expect seed-eating vertebrates to be exposed to lethal doses if they consume treated seeds spilled during sowing. Typically, maize seeds are each treated with ~1 mg of active ingredient, beet seeds with 0.9 mg, and the much smaller oilseed rape seeds with 0.17mg (Rexrode et al. 2003; Anon 2012; Krupke et al. 2012). A grey partridge, typically weighing approximately 390g, therefore needs to eat ~5 maize seeds, 6 beet seeds or 32 oilseed rape seeds to receive an LD50. A grey partridge typically consumes ~25 g of seeds /day (Liukkonen-Anttila et al. 1999), equivalent to ~600 maize seeds, so clearly there is the potential for birds to swiftly consume a lethal dose. By a similar calculation, 3 maize seeds treated with imidacloprid would deliver more than the LD50 to a mouse. The US Environmental Protection Agency estimate that ~1% of drilled seeds remain accessible to granivorous vertebrates (i.e. they are not buried during drilling), and this does not include spillages which may occur, for example when transporting grain or loading hoppers. With typical sowing rates of ~50,000 seeds/ha for maize and 800,000 seeds/ha for oilseed rape, we might expect sufficient seed to be available on the soil surface to deliver an LD50 to 100 partridge or 167 mice for every hectare sown. 

            Lopez-Antia et al. (2013) fed imidacloprid-dressed wheat seed to red-legged partridge (Alectoris rufa) for 10 days and obtained 58% mortality, with the survivors exhibiting a range of sublethal effects.  This mortality rate, although considerable, is less than we might expect from the calculations above.  Lopez-Antia et al. report anecdotally that partridge did not avoid dressed seed when offered both dressed and undressed, but speculate that treated birds ate less than control birds, and so received a lower dose than expected. This requires further investigation, in this and other species, to determine how much treated seed vertebrates actually consume in the field. De Snoo et al. (1999) describe incidents of poisoning of wild partridge, pigeon and duck by seed dressed with imidacloprid reported by members of the public in France in 1994-5 (a time when neonicotinoid use was very low), but other evidence for effects in the field is lacking and it is unclear whether public reporting is an efficient means of detecting such incidents.

Since 2013, there have been a number of other scientific publications linking neonicotinoids to declines of birds and other vertebrates, most of which are reviewed here. I would draw your attention to two in particular. Firstly, in a high profile paper in the journal Nature, Hallmann et al. (2014) demonstrate that geographic patterns of declines of insect-eating birds in the Netherlands are explained by local levels of environmental pollution with the neonicotinoid imidacloprid.  They conclude that this is unlikely to be due to direct toxicity, but that it is probably simply that in areas where insecticide use is high there are few insects for the birds to eat. Seems pretty plausible to me.

Secondly, a recent study of bird poisoning incidents in France shows that, between 1995 and 2014, there were 101 incidents involving 734 dead animals in which toxicological reports detected imidacloprid, and where the death is likely to be associated with agricultural use of seed treatments. 70% of these incidents happened during autumn cereal sowing. Grey partridges and various pigeon species were the ones most frequently killed.

According to Dr Hartfield, there have been no such incidents in the UK. This strikes me as very odd. Farming in France is very similar to the UK; most of the same crops are grown, and pesticide uses are very similar. I rang the UK Wildlife Incident Investigation Scheme to ask them whether they actually test dead birds for neonicotinoids. The person I spoke to did not know, and asked me to send in an email request, which I have done. When I get a reply, I’ll update the blog.

So, Dr Hartfield, my theories are more than “just theories”. “Real life” evidence from the Netherlands and France strongly supports them. The absence of direct evidence from the UK should not be interpreted as evidence of absence – if you don’t look for something, you won’t find it.   

The ongoing complacency of NFU, and their willingness to aggressively attack scientists who speak out against overuse of pesticides does them no credit. Farming bird populations are collapsing, along with most other farmland wildlife. Isn’t it time the NFU faced up to this, and took some responsibility?

 

Farmland bird population change (from JNCC)

 

References

Goulson, D. 2013. An overview of the environmental risks posed by neonicotinoid insecticides. JOURNAL OF APPLIED ECOLOGY 50: 977-987.

 

Are robotic bees the future?

Feb

07

Robot bee

 

There have been a number of scientific papers published in recent years discussing the possibility of building miniature flying robots to replace bees and pollinate crops. Clumsy prototypes have been tested, and seem to crudely work. If crops could be pollinated this way, farmers wouldn’t have to worry about harming bees with their insecticides. With wild bee populations in decline, perhaps these tiny robots are the answer?

While I can see the intellectual interest in trying to create robotic bees, I would argue that it is exceedingly unlikely that we could ever produce something as cheap or as effective as bees themselves. Bees have been around and pollinating flowers for more than 120 million years; they have evolved to become very good at it. It is remarkable hubris to think that we can improve on that. Consider just the numbers; there are roughly 80 million honeybee hives in the world, each containing perhaps 40,000 bees through the spring and summer. That adds up to 3.2 trillion bees. They feed themselves for free, breed for free, and even give us honey as a bonus. What would the cost be of replacing them with robots? Even if the robots could be built, complete with power pack and control devices, for one penny each (which seems absurdly optimistic) it would cost £32 billion to build them. And how long would they last? Some would malfunction, some would get caught out in the rain, some would be damaged by wind or spiders’ webs. If we very optimistically calculate the lifespan at one year, that means spending £32 billion every year (and continually littering the environment with trillions of tiny robots, unless they could be made biodegradable). What about the environmental costs of manufacture? What resources would they require, what carbon footprint would they have? Real bees avoid all of these issues; they are self-replicating, self-powering, and essentially carbon neutral.    

Thus far I have glossed over a vital further point. Pollination is not all done by honeybees. Numerous other insects pollinate crops and wildflowers, including butterflies, beetles, moths, flies, wasps and many more. These come in all sorts of different shapes and sizes suited to different flowers. Honeybees contribute at best 1/3 of crop pollination, averaged across crops. So we wouldn’t just need to replace the 3.2 trillion honeybees. We’d also need to replace countless trillions of other insects. All to replace creatures that currently deliver pollination for free.

Declines of bees are symptomatic of larger issues. It is not just bees that are declining; almost all wildlife is declining in the face of massive habitat loss and pollution across the globe. Even supposing we could create robot bees cheaply enough for it to be viable, should we? If farmers no longer need to worry about harming bees they could perhaps spray more pesticides, but there are many other beneficial creatures that live in farmland that would be harmed; ladybirds, hoverflies and wasps that attack crop pests, worms, dung beetles and millipedes that help recycle nutrients and keep the soil healthy, and many more. Are we going to make robotic worms and ladybirds too? What kind of world would we end up with?

Do we have to always look for a technical solution to the problems that we create, when a simple, natural solution is staring us in the face? We have wonderfully efficient pollinators already, let’s look after them, not plan for their demise. 

On neonicotinoids and impartiality in scientific research.

Jan

16

Last week my group posted online a lengthy review of new evidence (post 2013) relating to the possible risks posed by neonicotinoid insecticides to the environment: 

“The Environmental Risks of Neonicotinoid Pesticides: a Review of the Evidence Post-2013”

By Thomas James Wood, Dave Goulson

doi: https://doi.org/10.1101/098897

Free to view here: http://biorxiv.org/content/early/2017/01/06/098897

Funded by Greenpeace.

The rationale for compiling this review was that, in 2013, the European Food Standards Agency (EFSA) published a series of reports on three neonicotinoids (imidacloprid, thiamethoxam and clothianidin) which concluded that these chemicals pose an “unacceptable risk to bees”.  This conclusion led to the current EU moratorium which prevents the use of these three chemicals on flowering crops that bees might visit. EFSA are currently re-evaluating the position in the light of new scientific studies, and are expected to report back soon to the EU with a recommendation as to whether the moratorium should be rescinded, extended indefinitely in its current form or broadened to cover other uses (e.g. on non-flowering crops). It has been suggested that EFSA are compromised by close links with the agrochemical industry (though I have seen no evidence of this). Certainly industry are lobbying strongly to overturn the moratorium.  

Greenpeace asked us to write our own, independent review of the new evidence. Our review will make an interesting comparison with that produced by EFSA (now expected September 2017). Greenpeace paid the salary of my just-finishing PhD student, Tom Wood, for 4 months to complete this work with my help. For the record, other than Tom’s salary, they have not given any money to me or my lab, either recently or in the past. However, this does raise interesting issues about impartiality. I have previously pointed out that studies funded by, or carried out by, the agrochemical industry almost never find that neonicotinoids harm bees, while independent studies very often do find strong evidence of harm. This worries me because science depends completely on the honesty and impartiality of the experimenter. It is all too easy to bias results, consciously or subconsciously, in either direction. When patterns like this emerge, what is the lay-person to make of it? Sadly, it undermines public trust in science, at a time when good scientific evidence, and trust in this evidence, is urgently needed if we are to find a way through the myriad of terrifying environmental problems we are creating (climate change being an obvious example).     

So when we were offered money by a campaign group to write this review, we had to think very carefully. Greenpeace gave us written assurances that they would not attempt to influence what we wrote in any way, and they did not. Nonetheless, I am sure that some will say that this is just as flawed as industry evaluating the safety of their own chemicals. Of course there is one fundamental difference. When an agrochemical company conducts research on the safety of its own chemicals, it has a huge incentive to find a negative result. Pesticide sales are worth (literally) many billions of dollars per year. On the other hand, Tom and I get no direct benefit from publishing articles about pesticides, whatever we say. We might be more likely to get funding from Greenpeace in the future if they like what we write, so perhaps we are compromised to some extent too. On the other hand, if we published research that concluded that neonicotinoids were harmless we might be more likely to get funding from industry (though I think I may have burned that bridge long ago!), and industry has an awful lot more money than Greenpeace. So it is not clear that we have an obvious incentive to be biased, consciously or subconsciously, in one way or the other.

Nevertheless, I worry about impartiality and objectivity every day. I ask myself whether I am analysing patterns in the data correctly, or am I looking to confirm my own subconscious biases? When we conduct experiments in my lab, we try to report both negative and positive results as best we can (though journal editors don’t much like negative results). We recently published a paper which showed that low doses of the neonicotinoid clothianidin did not seem to have a measureable effect on learning or egg-laying in worker bumblebees (https://peerj.com/articles/1808.pdf ). If I had some sort of strange personal agenda to get neonicotinoids banned why would I publish this? With over 260 scientific publications to my name, I am not in desperate need of one more, and it might have been convenient to let this one slide, but we did not. We even paid the journal fees to get it published.   

Having spent six years studying neonicotinoids, I am pretty convinced that they are contributing to wildlife declines, not just those of bees. Hundreds of scientific studies from a huge diversity of different scientists on different continents conclude that they are harming bees, butterflies, aquatic insects, even birds and perhaps now bats (while a few studies found no effects). The balance of evidence seems to me to be overwhelmingly in one direction, despite industry efforts to obfuscate. That is my opinion, and it is not for sale. Unavoidably, all scientists in any field have opinions. Does this make us bad scientists? I hope not.

Of course, in an ideal world all research of this type would be funded entirely independently of stakeholders on either side. We don’t live in that world. So, if you have time, read the review. Make up your own mind whether it is fair or not.

The review contains no new data; it is simply a summary of what has been published in the scientific literature in the last four years. We have taken the unusual step of posting it on Biorxiv so that others can comment. This review has not yet been formally published; it is a work in progress. We encourage any interested party to give their opinion: have we missed critical information, have we wrongly interpreted studies? Once we have received comments, we hope to submit a final version for formal publication. This is not a procedure I have ever followed before, but seems to be a growing trend in this age of rapid, digital, open-access publishing.

So, comments please….