“Protecting Scotland’s honeybees” – but at what cost?

This post was originally written as a guest blog for Mark Avery’s excellent Standing Up For Nature, and I have reproduced it here. Please head over to Mark’s blog to read the comments (and my responses), and for all the latest on Mark’s campaigns, including #BanDGS.

Callum Macgregor is a postdoctoral researcher, currently based at the University of York. His research interests cover the ecology and conservation of pollinators (especially butterflies and moths) under the influence of human-induced environmental change. In his private life, that passion for insects extends to all wildlife, especially birds, and a particular enthusiasm for raptors and owls has led him to support the #BanDGS campaign. You can find him on Twitter at @Macgregor_Cal.

“Protecting Scotland’s honeybees” – but at what cost?

I have tried to link to my sources wherever possible in this blog. In another hat, I am an active promoter of ‘open science’ – the work of most scientists in the UK is publicly-funded and I believe that, by rights, the public should have free access to read their results. I’ve made every effort to choose sources for this blog that are available for all to read – either Open Access scientific papers, reputable journalistic reports, or bloggers that I trust. In a few cases, though, some of you will hit the academic paywall, and will only be able to read the article abstract. For this I apologise.

Last week, the Raptor Persecution UK blog reported on a reception hosted by the pro-driven grouse shooting ‘The Gift of Grouse’ organisation at Holyrood. RPUK were invited along by Andy Wightman MSP (Scottish Greens); besides them, the event was attended by a (small) number of MSPs, and a range of parties with vested interests in driven grouse shooting. Their report on the event is well worth a read. For me, as an ecologist whose research interests tie into the conservation of wild pollinators, one thing in particular caught my attention.

Among several photos taken at the event by RPUK was one showing a pamphlet handed out by The Gift of Grouse at the event (that photo is reproduced here by kind permission of RPUK). The pamphlet details the ways in which grouse moors are, apparently, conservation hotspots (though RPUK themselves have previously debunked the line referring to 81 bird species), and makes the claim that grouse moors contribute to the “conservation of heather moorland – essential to the production of heather honey and protecting Scotland’s honeybees”.

Gift of Grouse pamphlet(RPUK)
That pamphlet from the ‘Gift of Grouse’ (photo by Raptor Persecution UK)

Honey bee woes

It turns out that grouse-shooters have been pushing this angle for a couple of years at least (and regular readers of RPUK will be intrigued to see the prominence of the Hopes Estate in the linked article). You can certainly understand why proponents of grouse shooting would want to jump on this particular bandwagon. Recent declines in honey bees are widely reported in the media. As recently as 2014, a poll by Yougov found the British public considered declining bees to be the most important environmental issue of all – more so even than climate change – and bees to be the single species most worthy of conserving. The hysteria centres around so-called “Colony Collapse Disorder”, a phenomenon where honey bee hives are abandoned by their worker caste; it began in 2007, when American bee-keepers first reported much higher losses of overwintering hives than expected. Declines have continued since then, with neonicotinoid pesticides and varroa mites the most high-profile suspects among a wide range of candidate causes.

People are concerned, because honey bees are important – enormously so. Around 35% of global production comes from crops that are dependent on pollination by animals; and no animal species makes a larger contribution to this figure than honey bees. In the UK, bee-pollinated crops include such favourites as strawberries and apples, as well as the oil-seed rape that paints vast swathes of the English countryside in yellow every year. Their economic contribution is huge.

So you might be surprised that two weeks ago, an article was published in the highly-regarded journal Science arguing that declines in honey bees should not be viewed as a conservation concern (the paper itself is behind a paywall, but you can read the authors’ press release). The authors (Jonas Geldmann and Juan González-Varo, both researchers at Cambridge University) make a strong case that we should view the provision of crop pollination in agricultural settings as an entirely separate issue to the conservation of wild, native pollinators (and they are not the first to tackle this issue). They argue that, in settings where honey bees are not actively contributing to agricultural production, they do more harm than good.

Conserving wild pollinators

Like honey bees, wild bees (which also contribute to pollination) are also in decline. So are moths, butterflies, hoverflies – in fact, almost all of the main groups of pollinating insects. Back in the autumn, a study showing that flying insects had declined by 75% on German nature reserves made the front pages. The causes of these declines are likely to overlap heavily with the factors threatening honey bees – for instance, neonicotinoids are also thought to be important here. But crucially, honey bees themselves are also thought to play a role in these declines. Their impact is twofold – providing competition to wild pollinators for access to pollen and nectar, and introducing and spreading diseases to wild populations as beehives are moved from place to place. These effects can even cascade further into ecosystems, as declines in wild pollinators cause reduced reproductive success in native flowers that are unable to fully benefit from honey bee pollination.

Therefore, our actions in different places and habitats should be determined by our goals. If the goal is to boost crop pollination, then we should treat honey bees for what they are – a managed agricultural animal, like cows or chickens. This is not such a far-fetched comparison as it might seem. Beekeepers move their hives around to make the most of available resources, such as mass-flowering crops (in the process, boosting pollination in those crops, with tangible economic benefits to farmers). They medicate them to stave off the diseases that always accompany unnaturally high densities of animals, and artificially supplement their diets when food is scarce. There is no such thing as a wild honey bee in the UK, and they might not even be native.

Going to the heather

On the other hand, if the goal is to conserve pollinators, then we should do what’s best for wild pollinators. In part, that means increasing not just the quantity, but also the diversity, of flowers. This brings us back around to grouse moors, which do provide an enormous amount of nectar for a short period in August – in simple terms of the quantity of nectar provision, heather is one of the biggest producers in the UK. Some beekeepers take advantage of this, by “going to the heather”. The result is a high-end product that supermarkets sell for 3-4 times more than basic ‘mixed blossom’ equivalents. It’s nice – I have a jar in my cupboard (though it’s not from a grouse moor!).

The impacts of grouse-moor management – particularly muirburn – on floral diversity are complex. In naturally fire-prone ecosystems, such as the Mediterranean, wildfires are an important source of disturbance. Many annual plant species have evolved to respond to fires by flowering, which can lead to much greater quantity and diversity of flowers in the years immediately following a fire – though research I am currently involved in suggests that not all wild pollinators are able to capitalise on this. Through these processes, naturally-occurring fires of a range of sizes and with different time intervals between them (termed ‘high pyrodiversity’) can lead to an improvement in landscape-level biodiversity.

But Britain’s upland ecosystems are not naturally fire-prone, so much of the native flora is not adapted to recover. Moreover, muirburn leads to fires of roughly controlled size at controlled intervals – and so, very low pyrodiversity. A 2011 study led by researchers from the University of Liverpool reported that muirburn does maintain the current level of floral diversity, preventing a complete monoculture of heather; but that this current level of diversity is severely degraded compared to what our uplands should naturally look like (a topic covered on Mark’s blog previously). Moorlands are also less botanically diverse than other semi-natural or natural upland habitat types (see section 3.2.5 of the RSPB’s review of grouse moor biodiversity).

The problem with this low plant diversity is that nectar resources may be in short supply outside of the relatively short flowering period of heather, especially in the hugely-important springtime. Pollinators need a range of flowers, blooming at different times throughout the summer, to provide a constant supply of food. Beekeepers can time their visits to coincide with the heather. Wild bees don’t have that luxury, and those that are present will need to make the most of the temporary glut. Honey bees will provide competition during this time for floral resources and introduce diseases that will harm native moorland pollinators. Other aspects of grouse moors are also problematic – for example, the lack of trees is likely to exclude the many species of solitary bees (and one bumblebee) that nest in tree holes. We are talking about a worst-case scenario on grouse moors for wild bees and other pollinators – a degraded version of an already low-quality habitat. To argue that this is important for production of heather honey is perhaps true. To argue that it is vital to the conservation of honey bees is like saying that we should protect grassy pastures – for the benefit of cows.

Regular readers of Mark’s blog will be well aware that grouse-shooting interests often try to paint themselves as ‘conservationists’, with the best interests of upland wildlife at heart. They will also be aware that these claims are frequently misplaced: being generous, they appear to be based on a fundamentally-flawed view of what a healthy upland ecosystem should look like. The Gift of Grouse’s claim that grouse moors help honey bees seems to be another example of a wildly misguided attempt to align grouse-shooting with conservation interests. Please don’t fall for it!


Lived and learned: #BES2016 in review

I returned last night from the 2016 Annual Meeting of the British Ecological Society, held in Liverpool. Going to ‘the BES’ is fast becoming an annual tradition for me, as it is for hundreds of ecologists. As always, I had a great time, and learned a lot – not just fascinating snippets from the coalface of ecological science, but also a lot of more general lessons about how to get the most out of big conferences like this one, and a scientific career more generally. For my own sake as much as anybody’s, I thought I’d coalesce some of those thoughts here.

1. Engage with the public (don’t preach at them)

The conference was book-ended by talks that addressed the difficulty of turning your science into practice. Much of what ecologists do has a real-world application – whether we work in conservation, monitoring, or environmental change, I think we all want to see our research getting used, but it isn’t always as simple as ‘publish the paper, wait for people to read it’. Opening the conference, Mike Begon tackled Michael Gove’s comments that “people have had enough of experts”. Mike pointed out that people are more likely to respond to emotionally attractive messages than plain facts, no matter how persuasive those facts may be – but importantly, there is no reason why we can’t use facts as the moral justification to underpin those messages.

Later, in the final plenary, Hugh Possingham distilled his own experiences of trying to get his research into policy in his native Australia into the three simple messages in the tweet above. Hugh also highlighted the importance of ‘environmental heroes’, who can campaign on an issue over much longer timescales than is really possible for an academic. Somebody who definitely qualifies as an environmental hero retired this week after 13 years as CEO of Butterfly Conservation – best wishes for the future to the wonderful Martin Warren.

2. Step outside your comfort zone

This year’s conference marked the first time I had presented a chapter of my PhD (and hopefully soon a paper) that tackled DNA-based approaches for detecting ‘stuff in the environment’ and tested whether they could be applied to my area of interest, pollination interactions. I’m getting fairly experienced now at presenting talks at conferences – I’ve done both small conferences (where, conversely, the audience tends to be larger) and big conferences (where the audience can be much more topic-focussed and expert). But this was a methodological talk, about skills I had almost entirely learned within the last 12 months. What if I got found out?

I needn’t have worried. My talk went well and people seemed to be interested (and some of them said very nice things on Twitter!). A couple of people came up to chat afterwards who, it turned out, worked in related fields and had found elements of my talk useful – making those kinds of contacts was exactly why I’d wanted to give the talk in the first place!

On a related note, I spent Wednesday afternoon chairing a session on Global Change Ecology. Again, something I had never done before, but it worked out great, serving as simultaneously a gentle and a rigorous introduction to session-chairing. Gentle – because it was a small session in a big room, so it never felt too intimidating. Rigorous – because I faced all the challenges that chairing can throw up (speakers worried about their timing, stony silences when asking for audience questions, and at one point a hint of technical issues!). Next time I’m given the chance to chair a session, I’ll be much more confident.

3. Be nice

In a year of celebrity deaths, ecologists mourned the loss of Ilkka Hanski. I recently submitted a paper, based on my dissertation project, that investigated the spatial ecology of a moth species, and so I have a little familiarity with Ilkka’s work on metapopulations. Therefore, I decided to attend as much as I could of the session on Tuesday afternoon celebrating his life’s work. That such a session took place at all was remarkable – how many past attendees of the BES must pass on every year? – but I was struck by both the high turnout and the extraordinary fondness with which each speaker talked about Ilkka. Something to aspire to.

The following morning, Alison Hester – charged with the impossible task of giving the 12 Months in Ecology lecture after the year that’s been! – did a marvellous job of reminding us that it’s not all doom and gloom. There have been some fascinating discoveries this year, and great progress on the issue of microplastics. With Brexit looming and the election of President Trump, it’s easy to feel down – but it’s not certain how things will pan out, and maybe we ecologists, as a collective, can make a difference.

4. You’re not an imposter!

Imposter syndrome – almost all academic scientists will be familiar with it (as a side-note, congratulations to the BES for being proactive in organising a workshop about stress, and especially for targetting it at PIs, to help them look after their students. A great shame it had to be cancelled at the last minute, and I hope it will be back on the programme next year). After last year’s conference, I was honoured to have been named a runner-up for the Anne Keymer Prize for Best Student Talk. On Tuesday evening, I was invited to a drinks reception attended by Society prize-winners, current and past Presidents, and this year’s plenary speakers. Wow – I was terrified! Fortunately, the lovely Zoe Davies (who really did a marvellous job of putting this year’s programme together) spotted me looking nervous and swept me up, immediately introducing me to “Bill” (that’s Bill Sutherland to us mere mortals!). Within the hour I was chatting away to “Pedro” and “Jordi” – authors of this year’s Marsh Book Award winnerMutualistic Networks – about my own research on nocturnal pollination networks. Of course, I still felt like an imposter – but if anybody in the room felt in any way superior to me, they hid it well. Some of the best ecologists around – but totally grounded and humble.

5. The more you see, the more you know

This was my third BES; since starting my PhD I’ve also done two Royal Entomological Society conferences, two Butterfly Conservation/De Vlinderstichting conferences, and a host of other smaller meetings. At the first of these, I knew practically nobody and spent large chunks of the meeting standing awkwardly by my poster. This time out, it took me until Wednesday lunchtime to finally catch up with everybody I’d hoped to see at the BES, despite ‘networking’ during every single break. Along the way, I met a bunch of new people, ranging from MSc students to high-profile PIs, many of them through introductions by my existing contacts. I’m astonished by how many friends I’ve made in three short years in academia – long may it continue.

How [and why] should early career researchers engage with open science?

I was recently made aware of a competition being run by Naturejobs for students and ECRs (http://blogs.nature.com/naturejobs/2016/07/18/scidata16-publishing-better-science-through-better-data-writing-competition/?WT.mc_id=TWT_SCIDATA_1607_WRITINGCOMP_OA), to write a short piece about, in a nutshell, good practice in data management. One of the questions in particular stoked my interest: “how should early career researchers engage with open science?”.

After consideration, I decided not to enter, for three reasons: partly because I’m probably too busy to update my CV by the deadline for entry, partly because there’s no way I could limit myself to only 600 words on this important topic [edit: final count 1480 words!], but mostly because the piece I’d like to write could end up being too critical of the model of scientific publishing that is entrenched by journals like Nature. Nonetheless, I was sufficiently enthused that I decided to write the piece anyway, and publish it here.

How [and why] should early career researchers engage with open science?

To me, “open science” is a problematic term. That’s because it implies that this way of ‘doing science’ is in some way different from the norm – which would presumably be ‘closed science’. That is fundamentally unscientific.

I remember as a 10-year-old getting one of my earliest experiences of scientific experimentation in the classroom (I think it was the lemon battery experiment!). I’m sure the physics of the experiment were far and away beyond the comprehension of my classmates and I – what we were really being taught was the scientific method, and specifically how to write up an experiment. “Put enough detail into your materials and methods that anybody could repeat your experiment and get the same result”, we were taught.

Of course, in modern, hi-tech science, we have to adjust that to read “put enough detail in that anybody with access to the necessary equipment could repeat your experiment”. Not everybody will have access to a Next Generation Sequencing platform, or a powerful computer cluster, or a tract of farmland they can manipulate crops on – and that’s inevitable, and it’s fine. But one thing that should not be, that should never have been counted as ‘the necessary equipment’ is an institutional library with enough purchasing power to buy journal subscriptions. Now, I know that some fantastic tools like sci-hub have been set up to allow people who don’t have that equipment to access papers in subscription journals, but this should not be treated as an excuse to take the easy option. The burden, in my opinion, is with the researcher to make sure their audience doesn’t need to resort to such methods (which, I have it on the best authority, are technically illegal to use!). If your science is to actually be real science, it has to be openly accessible.

Given all that, here are my tips for ECRs on how to make your science open. These are all things that I didn’t know when I started my PhD, haven’t always followed to the letter during my PhD, but now consider to be essential to any papers I publish in the future.

1. Make your manuscripts Open Access

Let’s start simple. There is really no reason not to make your papers Open Access (OA) when you publish them. I think most people are now aware of the two tiers of OA that are available: “Gold OA”, where you pay to make your paper accessible from day one, and “Green OA”, where the journal paywalls your paper and you are allowed to self-archive (make a copy openly available online) after an embargo date – usually six months or a year.

Clearly if at all possible, Gold OA is the preferred option, but many people are offput by the high cost of the Article Processing Charge (APC) – for my recent article in Global Change Biology, this was USD $4000. One common misconception that I certainly had when I began my PhD was that I was personally responsible for this – not in the sense that it would come out of my personal bank account, but rather that it would come from my project budget. In more and more cases, this isn’t true. If you’re in the UK and your project is RCUK-funded, your university/institution pretty much has to pay your APCs – this is because they are given money by RCUK specifically to cover APCs for RCUK-funded projects! Even if you’re not RCUK-funded, it’s always worth asking your university to cough up (most university libraries now have a designated OA Officer) – they may have some of this money left over at the end of the year, or have designated some additional money for internal projects. If you’re not at the same university any more, it’s again worth asking your co-authors (especially your PI) if their university will cover the costs.

If you really, really can’t get your APCs covered, then at the very least you should self-archive as soon as possible. I’m not going to cover this in great detail, but here is a website (declaration of interest: I helped to research an update to this archive in 2014) that will illustrate how doing so can benefit you.

2. Make your scripts Open Access…

This one’s less obvious. Something I’ve regularly spotted since I first started participating in peer-review is a methods section that spends several paragraphs describing every intimate detail of the fieldwork and labwork, and follows it with something like “we analysed the data in R using GLMs”. To be fully repeatable, your analysis needs to be described in as much detail as the rest of your work. You could spend several more paragraphs describing every test you did – or you could archive your R scripts online (if you’re not using R yet, why not?!). If you archive your scripts, and point to them from within the paper, then anybody who isn’t sure what statistics you’ve done can simply follow your scripts through, line by line. Easy!

Github is a great tool for doing so. You can link it directly to RStudio on your computer (though it’s a bit tricky – here’s how) and upload the latest versions of your scripts as frequently or infrequently as you like. If you’re working in a ‘busy’ area and worried about being scooped, there’s nothing wrong with waiting until you’ve published the paper before you upload your scripts. Personally, I like to upload pretty much at the end of every day when I’m working on my data – this is because Git is also a fantastic version control tool, for those times when you change your mind about an edit you made last week, or even just accidentally delete a script!


3. …and your data too

Archiving your scripts is an important step, but it’s only of limited use if people can’t actually run the scripts. For that, they need access to your data. There are tons of options for this – many institutions will have their own archives for data (here is the data from that Global Change Biology paper, archived in CEH’s Environmental Information Data Centre), or there are more general options, like Dryad. Shop around and decide which is best for you.

As with scripts, some people will have concerns about being scooped – again, there’s nothing wrong with waiting until you’ve published everything you want to, but read this first. Even if people do reuse your data in their own studies, they are likely to (at worst) cite the study you gathered the data for, or (at best) invite you to be a co-author. So, there are potential benefits from archiving your data that go beyond mere reproducibility – it could actually increase your scientific productivity, with no extra effort!

Now, if you’re going to make both your scripts and your data openly available, it’s important that somebody attempting to use your scripts can follow every step you took. Here’s a set of useful tips for how to manage your data to make this happen.

4. bioRxiv

Tips 1-3 are all things I have done, or am currently doing. This one I hope to try in the future. ArXiv has been in use in physics, maths and related fields since before I was born(!), but really took off in the last 10 years – at the time of writing, 1,177,855 papers are openly available through it. More recently, bioRxiv has been started to provide the same resource to biologists. The idea is simple: once you think your paper is about ready to submit to a journal, you upload it to bioRxiv. At this point it’s given a DOI and can be cited by other authors. People reading your paper on bioRxiv can send you feedback, anonymously if they wish. It’s really no different to peer-review organised by a journal. You can then update your paper, including this feedback, and re-upload the latest version.

Once you’re happy that you’ve ironed out most of the issues people have, you can submit the paper to a journal (it might even be to your credit to point out that it’s already gone through peer-review on bioRxiv – a range of journals now accept one-click submission directly from bioRxiv). It will probably still be peer-reviewed, but the chances are that any problems have already been ironed out, those reviews are therefore more likely to be favourable, and your paper is more likely to be accepted. What’s more, it’s a great way of making your work OA even if you can’t pay the APCs (sidebar – I just wondered what the publishers think of this. Turns out, most of them are OK with it!).


So, if you’re an ECR and you haven’t yet thought about making your science open, try one, or two, or all of these steps. Once you realise that open science is a delight that brings huge benefits, rather than a chore that brings extra work, I guarantee you’ll be converted.

Moths expert: match report on Ronaldo insect encounter at Euro 2016 final

Callum Macgregor, Newcastle University

After a month of football, Euro 2016 drew to a close with Portugal defeating France 1-0 in extra time to lift the famous trophy for the first time. But the final game was a turgid affair, and perhaps the image most likely to endure involved a rather unexpected participant.

As Cristiano Ronaldo sat in tears on the turf, the reality of his game-ending injury sinking in only 25 minutes into the game, a moth fluttered around his eye and settled on his forehead. This moth was one of thousands in the stadium, pictured in clouds on the pitch as the players warmed up, and being swept with brooms from advertising hoardings.

What were they doing there? The bizarre spectacle appears to have been the result of a coming together of several exceptional circumstances.

A very brightly lit stadium

It is commonly known that moths display an extremely strong attraction to sources of artificial light, although we still don’t really know why. The stronger and brighter the light, the better – and this is our first exceptional circumstance.

Fully lit, the Stade de France shines like a beacon even amid the glow of La Ville Lumière. Worse yet, the format of the lighting – in a ring, facing inwards – means that once a moth finds itself inside the stadium, it would be near-impossible for it to escape the influence of the lights.

One large moth-trap.
Srdjan Suki/EPA

But many football games have been played under floodlights at big stadiums, and this game began while it was still daylight. This brings us to our second exceptional circumstance, then – the stadium lights were left on overnight on the eve of the game, presumably to aid the ultra-tight security effort that has surrounded the whole tournament.

The lights had a full night to attract as many moths as they could into the stadium. When fans and players began to arrive, those moths were nearing the end of their daytime slumber.

Migration spectacular

Still, though, brightly lit stadia have held events on consecutive nights before without experiencing mothy visitations. So to find the third exceptional circumstance, we need to look more closely at the moths themselves.

As the game unfolded, it became clear to those in the know that the vast majority of moths on display were representatives of a single species: Autographa gamma, the Silver Y – both names stemming from the γ-shaped marking on the wing. The Silver Y carries metallic patterns on its wing, like many other species in its sub-family, the Plusiinae, including the beautiful Gold Spot and my personal favourite species, the Burnished Brass.

When not bugging footballers, Silver-Ys enjoy feeding on flowers.
Arto Hakola/Shutterstock

Importantly for our investigation, these moths bear a remarkable similarity to another species recently making headlines, the cabbage-chomping Diamondback moth, which also migrate in huge numbers to UK shores.

Silver Ys make the journey annually from North Africa, travelling through France (including Paris) to breed in Britain. Scientists at Rothamsted Research found that in peak years they number almost a quarter of a billion, and up to four times that number return southwards in the autumn. By a twist of fate, the Euro 2016 final appears to have coincided with this year’s migrating Silver Ys reaching Paris on their northward journey.

Bad news for moths?

We know from several recent studies that the profusion of artificial light at night spells trouble, both for moths and the other organisms they interact with in the ecosystem. Moths have short lifespans – Silver Ys may spend as little as two weeks in their adult form after emerging from the cocoon – and in this time must complete their migration before finding a mate and a suitable location for their eggs. Time spent under the influence of a light is time wasted.

With luck, organisers at the Stade de France will have the sense to leave the stadium lights off on Monday night. Returned to (relative) darkness, most of the stadium’s temporary lodgers will be able to escape the arena and continue their journey merrily northwards – perhaps, for some, to land on British soil within the coming days much to the excitement of moth lovers who, like me, eagerly await their arrival.

The Conversation

Callum Macgregor, PhD Candidate, Newcastle University

This article was originally published on The Conversation. Read the original article.

Channel-hopping moth plague: our clothes are safe, but mind the cabbages

Callum Macgregor, Newcastle University

The next great plague has descended, and this time it’s moths. Diamondback moths have been crossing the English Channel over the past fortnight in far greater numbers than usual.

Those of you reaching for moth-balls and carpet sprays, stop. There are only two species of British moth (from a cast of thousands) that damage clothes, and the diamondback is not one of them. You, the reader, really don’t need to worry – unless you grow cruciferous vegetables like cabbages or broccoli.

Plutella xylostella – more commonly known as the diamondback – is one of the world’s most widespread and prevalent agricultural pests; so widespread, indeed, that scientists disagree as to where exactly its native range lies.

Their success belongs in part to their preference as caterpillars for eating plants in the Brassicaceae family. This amazing group of crops (notably the species Brassica oleracea) has been selectively bred over hundreds of years to make use of almost every part of the plant, and now contains many popular vegetables such as cabbages, broccoli, Brussels sprouts and turnips, as well as oil-seed rape. The moths lay eggs on brassica leaves; a week later, caterpillars hatch and start eating. An infested plant can quickly be reduced to little more than leaf stems.

Cross-Channel travellers

Despite being one of the smallest moth species to occur in the UK, with a wingspan of under 15mm, diamondbacks are capable of dispersing vast distances, using the wind to make up for their small size. Research has shown that without assistance, diamondbacks are only capable of flying 35 metres – yet when carried along by the wind, they may travel hundreds of miles in a single day.

It is this ability to disperse that leads it to British shores. Every summer, adults cross the Channel and attempt to breed in the UK. A number of butterfly and moth species employ this strategy. In some cases, such as the Painted Lady butterfly, the offspring will return south ahead of the winter. For others, including diamondbacks, the offspring will attempt to remain, but British winters are typically too cold for them to survive.

What’s for dinner? Cabbage, broccoli and Brussels sprouts.
Yuangeng Zhang / shutterstock

For the moths, these fatalities are an unfortunate side effect of a highly dispersive life history; by having offspring constantly travelling beyond the edge of their range and attempting to breed, the moths ensure that no available space is wasted. Should some of the dispersing moths find a new area that is suitable for breeding success, they will benefit enormously from a lack of competition with their peers and, potentially, the absence of specialised predators and parasites. Thus, evolution favours and preserves these intrepid explorers.


And it is once the moths begin to breed that the problems begin for farmers and gardeners, because these are not your average pest. Diamondback has been referred to in some coverage as a “super-moth”. It’s a title it certainly deserves.

The species has proven itself to be extraordinarily adept at evolving resistance to pesticides. Wild populations have developed significant resistance to almost every significant synthetic insecticide in use, including one of the main classes, pyrethroids.

Perhaps more impressively, diamondback was the first insect recorded to have developed resistance in the field to the bacterial pesticide Bacillus thuringiensis; only one other species is known to have managed this since (the “cabbage looper”, a pest moth named after its favourite food). Interestingly, this has led scientists to target it with the same genetic tools as are employed against the mosquitoes that transmit dengue fever and Zika virus. Field trials are planned in the US for this summer.

Tough times on the veg patch

In the short-term, perhaps. The influx of moths will soon begin to produce larvae, and these may cause substantial damage to crops where they are able to escape death by insecticide. The damage will be most severe to farmers of leaf crops, such as cabbages or kale, as the holes left behind in leaves by caterpillars make the crop unsellable.

Diamondback caterpillars leave cabbage unappetising and unsellable.
Rothamsted Research, CC BY

Looking at the longer term, this year’s invasion will die out over the winter. Next year there will be another, but this is nothing new: these moths come to the UK every year in substantial numbers. I spent the summer of 2014 collecting moths on farms in Oxfordshire for a study on the effects of light pollution on moths. Out of the 203 species of moth I recorded, diamondback was the 26th most common, forming around 1% of my total catch.

Britain’s cabbage-growers have been dealing with diamondback for years and have managed to persist thus far. They may have a hard summer ahead of them but it is not without hope. Although globally diamondbacks have developed resistance to almost all pesticides, most populations are only resistant to a subset of these, and scientists at Rothamsted Research are already studying the current influx to identify their weaknesses. Armed with the results of that research, farmers may be capable of restricting the damage.

The Conversation

Callum Macgregor, PhD Candidate, Newcastle University

This article was originally published on The Conversation. Read the original article.

Fatal attraction: how street lights prevent moths from pollinating

Callum Macgregor, University of Hull/Newcastle University

For centuries, we have observed that artificial sources of light hold a strange fascination for moths. Despite decades of research, we still don’t know the cause of this attraction. Some theories put it down to the way moths navigate; others think it’s a mechanism to help them to escape from perceived danger. But the truth is, little evidence exists to support either of these ideas.

Whatever the cause is, research has shown that this deadly attraction may have even more sinister consequences than we first thought. In an open access paper in Global Change Biology, my colleagues and I describe the first evidence which shows that the effects of artificial light on moths may have serious implications for the wider ecosystem.

There has been plenty written about the danger posed by declining bee and butterfly populations, on the basis that some plants rely on these insects to carry pollen and fertilise flowers, in order to reproduce. But many people aren’t aware that moths also perform this task: our study of field sites across Oxfordshire found that one in four moths were carrying pollen, from at least 28 different plant species.

Danger zone.
from http://www.shutterstock.com

And like their cousins the butterflies, moths are in trouble: according to Butterfly Conservation’s Richard Fox: “the total abundance of moths in Britain has decreased by over a quarter since the 1960s”. Research indicates that artificial light, such as street lamps, has contributed to this decline by affecting moths’ development, reproduction and ability to escape predators.

Now, our data suggests that street lights are also directly thwarting night-time pollination, by attracting moths upwards, away from the fields and hedgerows. We found that the abundance of moths at ground level was halved in lit areas, while flight activity at the height of the street light was nearly doubled. The diversity of species was also reduced at ground level, with 25% fewer moth species in lit areas, compared to places without street lighting.

This change is likely to disrupt nighttime pollination by moths, and indeed we found some evidence that moths may carry less pollen, from fewer plant species, in lighted streets. This could mean that the impacts of street lights go beyond posing a health risk to moths. Plants that rely on moths for pollination would also suffer if their reproduction is impeded – and this might, in turn, affect organisms that eat those plants or drink their nectar.

In a best-case scenario, some of these so-called cascading effects might be mitigated where flowers can rely on other insects such as bees for pollination. But there are further factors driving declines in pollinator populations, such as climate change, pesticides and habitat loss. Now, our research suggests that artificial light can be added to the list.

Unnatural selection

So how can we protect these beautiful, under-appreciated insects and the important role they play in our environment?

The Spindle Ermine moth knows what’s good for it.
gailhampshire/flickr, CC BY

Another recent paper published by researchers in Switzerland suggests that moths may be evolving to be less strongly attracted to lights. Under controlled experimental conditions in a flight cage, they found that Spindle Ermine moths from urban populations were less likely to be captured in light-baited moth traps than their rural counterparts.

These findings suggest that moths which can resist the temptation of lights put themselves at a significant advantage over their peers. Over time this has led city-dwelling moth populations to become less attracted to lights, through natural selection. But this is all relative: urban moths are still far from immune to the deadly allure of urban street lights.

We can’t simply switch street lighting off: although the evidence for its actual benefits is questionable, it certainly contributes to many people’s feeling of safety and security when outside after dark and proposals to turn lights off are often unpopular.

But if we don’t wish to wait for the slow crawl of evolution, it may be that recent advances in street lighting technology can help to mitigate the impacts of artificial light. For example, developments born out of a desire for energy efficiency could also minimise the impact of street lighting on moths. Measures such as switching on street lights for part of the night, dimming them or introducing motion-activated lighting would reduce moths’ exposure to street lights. Similarly, the flexibility of LED lights might allow for the creation of street lights that are less attractive to moths, which respond most strongly to short-wavelength blue light.

Nevertheless, artificial light at night continues to increase as we seek to drive darkness from the streets. Our research is another warning that this may have far-reaching consequences for the organisms around us.

The Conversation

Callum Macgregor, PhD Candidate, University of Hull

This article was originally published on The Conversation. Read the original article.

Street lights alter moth activity

This post was originally written for the Butterfly Conservation blog and focuses on the contribution this marvellous charity makes to our research on moths, pollination and light pollution.

Newcastle University PhD student Callum Macgregor explains how a new study has revealed that street lights alter the activity of moths.

The findings of the study, an Open Access paper published today in the scientific journal Global Change Biology, could have potentially serious implications for wildflower species. 

The study forms part of a three-and-a-half  year research collaboration between Butterfly Conservation, the Centre for Ecology and Hydrology (CEH) and the Universities of Newcastle and Hull.

Small Elephant Hawk-moth with Greater Butterfly Orchid pollinia (John Bebbington)3
Small Elephant Hawk-moth carrying Greater Butterfly Orchid pollen. (c) John Bebbington

It is widely accepted that butterflies are among the most important groups of pollinators but the majority of our species of Lepidoptera are moths. As a PhD student co-supervised by Butterfly Conservation staff, my supervisors and I have set out to establish the importance of moths to pollination in the UK and abroad. In a paper published last year (which you can read here), we reviewed evidence from around the globe that moths are important pollinators of a diverse range of plant species, including some evidence of a role in the UK.

Butterfly Conservation’s 2013 report The State of Britain’s Larger Moths showed that our native moths are in trouble, with two-thirds of widespread and common macro-moth species in decline over the last 40 years.

Among the likely causes of this decline is the continuing increase in the use of artificial light at night to illuminate our streets, parks and gardens. Moths are known to be attracted to sources of artificial light and there is a growing base of evidence that this could affect their growth, reproduction and ability to escape predators. We were interested in whether the effects of artificial lights on moths could alter their role as pollinators.

Our research revealed that moth activity in street-lit areas shifts from vegetation level to lamp-post height, with lights attracting moths away from the fields and hedgerows. Moth abundance at ground level was halved in lit areas but flight activity at the height of the street light was nearly doubled. Around a quarter of moths were carrying pollen (from at least 28 plant species), supporting the idea that moths make an important contribution to pollination in the UK. However, we found some evidence that moths may carry less pollen, and from fewer species, in street-lit areas.

Dr Darren Evans of Newcastle University, one of my lead PhD supervisors, compares these findings to worries about more well-known pollinators, bees and butterflies. he said: “There is a great deal of concern at the moment about our falling pollinator populations and the knock-on effect on plant pollination. Our research suggests that it’s a process that is being damaged on two fronts – night and day”.

The project is funded under the NERC Industrial CASE studentship scheme, which aims to place PhD students into “mutually beneficial research collaboration between academic and non-academic partner organisations”. Acting as the CASE partner on the project, Butterfly Conservation staff including Head of Recording Richard Fox, Zoe Randle, Les Hill, Mark Parsons, and Director of Conservation Nigel Bourn have all been able to advise and shape this research.

Richard in particular is one of my PhD supervisors and a co-author on the paper. He said: “Moths are an important part of the UK’s biodiversity, as pollinators of wild flowers and as food for many birds and predators. The role of artificial light in causing moth declines remains unclear, but this new research indicates effects not just on moths but on the whole ecosystem”.

We hope that our findings can help to conserve this beautiful and charismatic group of insects and the flowers that depend upon them. Dealing with an issue such as street lighting can be complex:

Dr Michael Pocock of CEH, my other lead supervisor, said: “Street lighting at night is important for road safety and people’s security but our research is just the latest piece of evidence showing the unintended negative effects of street lighting on wildlife”. We are now investigating a number of recent advances in technology, such as the rise of LED street lighting, to see whether they may offer opportunities to reduce these negative effects.

Follow me on Twitter @Macgregor_Cal