Ep 56: Bee kind: The buzz on global insect declines (with Dave Goulson)
Why are bee populations declining? How can we reliably monitor insect populations when many are so cryptic? And what steps can we take to ensure that populations remain viable?
In this episode, we talk with Dave Goulson, a professor of biology at the University of Sussex. Dave studies the ecology and conservation of insects, particularly bumblebees, and he is the founder of the Bumblebee Conservation Trust. Bumblebees and wild bees provide pollination services for over 50% of the food we consume—so ensuring their long-term viability is critical to our food security. Dave says that bees and other insects face many challenges, especially from neonicotinoid insecticides and from protozoan diseases and ectoparasites. We talk with Dave about the effects of anthropogenic stressors and the rapid action needed from individuals, farmers, policymakers, and governments to help maintain healthy bee populations.
Cover photo by Pieter Haringsma
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SPEAKERS
Art Woods, Dave Goulson, Marty Martin
Art Woods 00:07
In January, the Proceedings of the National Academy of Sciences dedicated an entire issue to the global decline of insects. Dozens of scientists concluded that climate change, habitat loss, pesticides and pollution were sending many insect species on a downward spiral.
Marty Martin 00:22
It’s bad enough that some scientists and journalists are calling it the insect apocalypse. The phrase gained traction in 2017 after a group of European scientists published a paper highlighting dramatic insect declines in Germany.
Art Woods 00:34
They analyzed data from an entomological society in Germany that had been trapping insects for decades. Shockingly, the total weight of insects trapped fell by three quarters over the course of 27 years. That result inspired a wave of gloomy headlines about the future of insects, but also renewed interest in monitoring their status.
Marty Martin 00:54
Articles in the recent PNAS issue suggest that the number of insects in many areas is declining by about 1 or 2% each year. Over a few decades, that adds up to a huge impact.
Art Woods 01:05
However, ballpark estimates like this may not provide a full picture. It’s rare to get data from long term monitoring projects, and many of these focus on a few conspicuous groups like butterflies, moths and bees rather than sampling more comprehensively across taxa. These kinds of studies are also mostly conducted in Europe or the United States, even though most insects live in the tropics.
Marty Martin 01:27
In other words, it may be premature to declare that the insect apocalypse is upon us, but even so, it’s clear that we need to take action to reverse the trend. Insects provide an enormous set of services to humans, and without them we’d be in big trouble.
Art Woods 01:41
One obvious and important service is pollination. Between 8 and 10% of all the food we eat depends on pollinators, and wild insects do most of the work. Today’s guest, Dave Goulson, says that fact alone should be enough to make people care about global insect declines.
Dave Goulson 01:57
There is this kind of common misconception out there that the honeybee pollinates all of our crops and with that, you know, we don't need any other pollinators at all, which is absolute rubbish. In the UK, there was an analysis done of this, and it concluded that honeybees contribute a maximum of 30% of crop pollination. So you know, the bulk is being done by these wild insects that nobody looks after at all, we just assume are going to turn up and obviously the worrying thing is that they're not anymore.
Marty Martin 02:27
Dave is a biologist at the University of Sussex who studies bumblebees and the sustainable management of pollinators. He was a co author of the study of the German insect declines in 2017, and is an outspoken advocate for insect conservation. Recently, his lab has been investigating the impacts of pesticides on bumblebees in particular.
Art Woods 02:45
On this episode, we talked with Dave about the decline in wild bee populations, efforts to monitor wild bees, key factors contributing to their declines and what those declines mean for us.
Marty Martin 02:55
At the end of the show, we'll discuss how our food system can be made more pollinator friendly, and what individuals like you can do to prevent insect declines. David argues that with some major changes, it is possible to feed our growing population and preserve pollinators.
Art Woods 03:09
I'm Art Woods.
Marty Martin 03:10
And I'm Marty Martin.
Art Woods 03:11
And you're listening to Big Biology.
[music break]
Art Woods
Well, Dave it's just fantastic to get you on the show. We've been talking about insect declines for some time and wanting to get you on the show to talk about this, so I'm glad we finally get a chance. And I want to, I want to just jump right in with both feet and ask how bad is it? You've, you focus particularly on bees around the world, and you've documented declines in several groups, including bumblebees. But let's so let's just start with bees. How bad is it?
Dave Goulson 03:56
Yeah, so bad. I mean, I think there's no doubt at all that wild bees, but not honeybees, and it's important to make that distinction, wild bees have declined a lot. Not every species, some are clearly much tougher than others for reasons we don't fully understand. And I have to kind of throw in the caveat that actually the majority of bee species are not really monitored, but the ones that we are monitoring, or that which we have some kind of data for, predominantly show declines. We've got better data for bumblebees than anything else. We've got better data for Europe and North America than for any other region. But certainly the most obvious sign of decline is we've seen these really massive range contractions in quite a few species. So you know, in the UK, we've lost two species in the 20th century, and quite a few others that used to be common bees, and now to find one you've got to drive hundreds of miles you've got to go to one of the last kind of little populations that's clinging on in a nature reserve somewhere. One species has gone extinct, a bumblebee has gone extinct in North America, Franklin's Bumblebee. So that's obviously the sort of end point of range contractions. And thankfully, most haven't got there yet, but there are quite a few heading that way the rusty patch bumblebee, another North American species, has also undergone these really spectacular range contractions. And that used to be a very common insect across the whole of the eastern side of North America. And now, you know, it's down to a handful of individuals almost,
Marty Martin 05:45
Dave, can we circle back to something you said a minute ago to try to get, be as explicit as possible about the scope of the problem. How many bees are there in the world? How many species of bees are there? And I mean, I want to hear the answer to that question en route to who is it that we're monitoring? And you know, what fraction of total bees are we attending to in any detail?
Dave Goulson 06:07
So there are 20,000 species of bee in the world, and the sad truth is, we haven't got a clue what's happening with most of them. There is no long term monitoring scheme in place for, this, this is actually you could make the same statements about insects generally, you know, there are 1.1 ish, million named species of insect. And for the very large majority, we haven't got any data at all on any measure of their population change or range change or anything else, really.
Art Woods 06:44
Somebody just described them at some point. And that's it.
Dave Goulson 06:47
Yeah, exactly.
Marty Martin 06:48
They have a name.
Dave Goulson 06:49
Yeah, you've got a type specimen in a museum somewhere. We know where it was caught, and, you know, there may be a few other sporadic records. That's it, you know. So it's pretty kind of worrying, in a sense, and of course, we also know that there are lots of species we haven't even described. So obviously, we don't know what's happening with them, because we haven't even got to the point of having one on a pin.
Marty Martin 07:13
Don't even know what they are, yeah.
Art Woods 07:15
And so how many do you estimate that there are altogether?
Dave Goulson 07:19
Now don't ask me to.
Art Woods 07:20
Okay, okay.
Dave Goulson 07:22
That's not my area. But I mean, other people have tried to extrapolate how many insects there might be in the world. And, you know, the, the most conservative estimates suggest maybe two or 3 million, and the top end is maybe 10 million, but, you know, there's a pretty, pretty big confidence intervals, we don't know.
Art Woods 07:43
Yeah, fair enough.
Dave Goulson 07:45
Suffice to say, there's an awful lot, and for most of them, we haven't got a clue. I mean, that so when, and also the geographic, the geographic distribution of our knowledge about insects is extremely biased and patchy. So basically, we know quite a lot about European and North American insects, relatively speaking, and almost nothing at all for all of the, presumably, extraordinary diversity of insects living in South America, Africa, and Asia, and pretty much Australia too, just no long term monitoring of any species. So, you know, it's very hard to make any sensible, accurate, reliable statements about what's happening to insects globally, given that the place where the most insects live, we just don't know. You can guess you know, I mean, you've only got to see an aerial photograph of oil palm plantations stretching across Indonesia, where it used to be rainforest to think well, it's a pretty, seems pretty likely there are fewer insects there now than there used to be, but nobody's counting, sadly.
Marty Martin 09:02
Why don't we know those things? Is it, you know, anytime insects come up, to especially non biologists, they're too icky and too gross and creepy crawly? I mean, is it sort of the lack of charisma for most of them, say to birds, the passion that you know so many people to have to go in and to each encounter their birds? Or is it just the difficulty and the cost of doing it accurately? Or some combination?
Dave Goulson 09:24
I think it's all of those things. I mean, there are so many of them that it's really difficult to, to set up a monitoring scheme for, so people, what you can do is you can set up a monitoring scheme for one of the the more easily identified groups, and it has to be a group that isn't, doesn't have too many species, but the classic is, of course, butterflies. We do a lot of monitoring of butterflies in North America in Europe, because they're big, they're colorful, people kind of like them, they're relatively easy to identify. And so it's possible to get, you know, citizen scientists out there walking transacts counting butterflies, you can just about do that with bumblebees, we've got a scheme running now in the UK for bumblebees. And maybe if you're really lucky, you might do it on a limited scale with one or two other insect groups, dragonflies maybe or hoverflies, possibly to push. But then you're still only really scratching the surface of, you know, insect abundance. There are so few people that can identify most, you know, you look at say parasitoid wasps, which is, you know, an enormously diverse group, there's only a handful of people in the world that can identify them, and then you've got to kill them and get them under a microscope and, you know, count the hairs on their hind leg or whatever it might be. So it's just not really, the logistics of monitoring insects in any kind of detailed way are really daunting. Plus, of course, you know, they just don't have the number of people interested in them that perhaps bigger, more charismatic creatures do.
Marty Martin 11:15
Well, maybe we, we do need to turn to sort of the negative side of the conversation and start to touch some of the factors that are driving bee declines. And there's a big list of them, so we probably don't have time today. And maybe we'll become too depressed to make it through the conversation. But could we start with habitat loss? I think that's one of the more prominent ones. So what sorts of habitat, losing those sorts of habitat is most negative for bee populations?
Dave Goulson 11:46
Yeah, I mean, at the end of the day, bees need, they need flowers, primarily, and somewhere to nest. And I think most people would agree that probably the availability of flowers is the one that's more commonly limiting of those two things. And just the modern landscape tends to have rather few flowers in it, if you look at a farmed landscape compared to what it used to, more compared to kind of natural or semi natural habitats. And, certainly in a European context, it's slightly different in North America, but in Europe, we used to have huge tracts of species rich grasslands, particularly hay meadows, and also chalk downland, which are well, usually these days regarded as sort of a manmade habitat, semi natural habitat created by grazing and by hay cutting, practices that went on for hundreds of 1000s of years. But they maintained this really species rich habitat with lots of really high densities and diversity of flowers. And they're fantastic places for insects of all types. So just in the UK, which is a pretty small country, we used to have about 7 million hectares of species rich grassland, up to about 1920. And then in the next 70 years, we destroyed 97% of that habitat, which you know, and replaced it with, either with arable crops, which tend, you know, either to have no flowers unless they happen to be a flowering crop, and then there's just a glut of flowers for two weeks, and then it's gone again. Or the other the other habitat, which is, kind of often replace these species rich grasslands, is improved pasture, as it's known in farming terms, which is usually just a rye grass. A monoculture of bright green pasture. Good if you're trying to feed cows.
Art Woods 14:00
Good for a cow bad for bees, yeah.
Dave Goulson 14:02
Exactly. So certainly, you know, looking at Britain, most of the species of bee that have declined used to be found in these flower rich grassland areas.
Art Woods 14:14
So are these insect declines motivating anybody to try to get back to more diverse, you know, grasslands and supportive agriculture. So sort of dial back the clock somehow in terms of species diversity?
Dave Goulson 14:27
Yeah, this I mean, there are interesting things happening. I mean, for a long time now there've been moves to, you know, there are subsidies available to farmers in Europe, for example, to put in flower strips to reduce cutting of hedgerows and they can also get subsidies to actually replant or recreate from scratch flower rich grasslands. But you don't see that much of it. The you know, many farmers haven't really engaged with it the funding isn't really adequate. It's not really been a game changer, because, well certainly so in the UK, we started funding these agri environment schemes 25 years ago at least. And yet all the evidence we have is that insects are still declining, sadly.
Art Woods 15:20
Well it's still probably in most people's economic interest to not bother with that stuff, right. I mean, you know.
Dave Goulson 15:26
Yeah, I mean, you know, some of the schemes are fairly well funded. I mean, you know, there's some of them that pay about 500 pounds a hectare for the top end every year. So that's the kind of restoring a species rich grassland. But the problem is that, or one of the problems I think, is that it's very unfamiliar territory to farmers, you know, they've become used to growing crops, they know how to grow crops, they don't know how to restore the species rich grassland and how, they don't know what it should look like. They you know, they can't they've been gone too long for the farmers. It was their grandparents remembered what they looked like.
Art Woods 16:02
Yeah, right, shifting baselines for them too right.
Dave Goulson 16:04
Yeah, they don't have the equipment.
Art Woods 16:06
Yeah, and there's probably a social effect also, you know, if you have too many weeds growing on the side of your field, right, then it doesn't it doesn't look right.
Dave Goulson 16:13
Well absolutely, there is a sort of farmer tidiness, just as there is with gardens, actually, there's a whole interesting world of conversation to be had there. But yeah, so so, you know, so far, although governments have created national pollinator strategies, and there's all this talk about what we might do to, to kind of, you know, in the way of nature friendly farming and this kind of thing, but the reality is, it hasn't delivered much yet. I think we need a real kind of, you know, step change in, in how much of that kind of thing we're doing, if we're really going to make any difference, it feels a bit like a, you know, a drop in the ocean at the moment.
Marty Martin 16:56
So, you know, in terms of habitat loss, it's really its habitat change, it's loss in the sense that the species we're trying to conserve no longer have what they would prefer or need. But um, do we know anything about urbanization effects? I mean, for certain bee species, in particular, I'm interested to know if there's a bee equivalent of a cockroach or you know, the black rat or something like that. Are there species that are thriving? And are they thriving because of urbanization?
Dave Goulson 17:24
Yeah, I mean, not quite a direct analogy to rats, perhaps. But, there are,
Art Woods 17:29
You won't go that far.
Dave Goulson 17:30
There are certainly, so we did some work, 15 years ago now, where, well two things we did. One was we got young bumblebee nests and we put them in different habitats to see how they did. And one of those habitats was, was urban areas, and then we had various different, we had farms, conventional farms, and farms with extra flowers and this kind of thing, and the ones that did best of all were the ones in the gardens. Much better than, even the farms with extra flowers were nowhere near as good as the gardens. And we've also done stuff looking at using genetic markers to fingerprint bee workers, and then count how many sisterhoods there were in different areas as a measure of how many wild colonies there are. And again, you know, the estimates of nest densities are much higher in urban areas, sometimes quite extraordinarily high. So certainly the, but only for common species, so there seem to be a few species of bumblebee that are really adaptable. And, you know, this is the same with most groups, birds, other groups of insects, whatever, there seem to be a few really robust species that can cope with whatever we throw at them, and then lots of others that that quickly expire, you know, they can't cope at all, but the adaptable ones seem to have adopted gardens as pretty good habitat. And obviously, they do tend to have quite high densities of flowers, it's, you know, it's very patchy from one garden to the next. But if you're a bee, and you can happily fly over a few fences, there's always a garden somewhere in an urban area, with flowers. So compared to farmland, urban areas are not bad for adaptable species that can cope with, you know, the sort of challenges of urban areas and there must be lots of pollution, there's, you know, probably traffic collisions to cope with.
Marty Martin 17:31
Not that far.
Dave Goulson 17:32
There's other downsides, but there are some gardens. Yeah. We're gonna take a quick break to bring you a message from our sponsors. Support for this episode comes from Hopkins Marine Station of Stanford University.
Marty Martin 19:41
Founded in 1892, Hopkins Marine Station, located 90 miles south of Stanford's main campus on the Monterey Bay, is the oldest marine laboratory on America's west coast.
Art Woods 19:50
Hopkins scientists work both locally and at field sites around the world and their research addresses fundamental questions at every level of marine biology from genes to ecosystems.
Marty Martin 19:59
For example, a team from Hopkins recently attached cameras to bluefin tuna to understand how they move through their environments. Another team is investigating how to restore tropical reefs using heat resistant strains of coral.
Art Woods 20:10
Find out more about research and educational opportunities, visit hopkinsmarinestation.stanford.edu That's hopkinsmarinestation.stanford.edu.
Marty Martin 20:23
The Zoological Lighting Institute funds the sciences of light in life, for the arts for animal welfare and for wildlife conservation.
Art Woods 20:30
Recognizing that natural light is a central aspect of animal health and ecological function, the Zoological Lighting Institute promotes understanding by including scientific and artistic perspectives in conversations about light, so that proper and sustainable approaches to care and development can be taken by communities around the globe.
Marty Martin 20:47
ZLI understands that natural light is a key element of wildlife habitat, Artificial light at night and other modifications to the luminous environment, such as glass and asphalt, have radical implications for the physiology, sensory ecology and integrative biology of animals and their role within ecosystems. ZLI promotes scientific research to improve understanding as to what artificial changes mean for animals and to human communities that depend on them.
Art Woods 21:10
Find out how you might support ZLI's work at zli.org, by participating in, sponsoring or learning through its programs today. Um, let's let's turn to a different cause of declines. I want to talk about parasites and diseases just for a few minutes. And this is particularly interesting to me in the context of honeybees interacting with wild bees and thinking about diseases going both both ways. And I think you know, in the news media, you hear a lot about honeybee diseases, and they've accumulated lots of bad things over the last few decades. But just sort of give us a state of disease ecology among bees generally and how important those routes are back and forth.
Dave Goulson 21:53
Yeah, it's, it's a really interesting area. And there's been a lot of published research in recent years, but still, we're just scratching the surface really, because we know so little about the diseases of wild insects. Almost all bee disease research until the last 10 or 15 years was on honeybees. And in fact, almost all insect disease research was on honeybees. And we know honeybees suffer from a, quite a range of parasites and pathogens, viruses and fungi and bacteria and all sorts, some of which are specific to honeybees, but many of them seem to be generalist bee diseases or sometimes insect diseases. So for example, deformed wing virus, which is very common in honeybees, will happily infect wild bees. And there are records of it turning up in in non bees, wasps, and even if I recall correctly, hoverflies. So these are just kind of insect diseases, you know, we think of them as honeybee diseases, just because that's where they were discovered, but actually, the honeybee may not be the main host at all, sometimes.
Art Woods 23:07
And are they more widespread, given people moving honeybee colonies around the landscape for pollination services? So is that spreading this all over the place?
Dave Goulson 23:15
Yeah, so that's the problem. You know, of course, these diseases are kind of natural on the whole, you know, and things like the varroa mite, it's, you know, has as much a right to live on this planet as we have as far as I'm concerned. But the trouble is, we've messed things up by shifting them around. And, you know, people started moving honeybees around the world hundreds of years ago, before we even knew there was such a thing as a bacteria or a virus. So obviously, they didn't check those colonies to make sure they were clean. And this has continued to even up to the present day that we're still pretty lax with bee hygiene. So honeybees get moved all over the world and we've accidentally spread a whole range of their diseases with them and sometimes with with serious consequences. So for example, there's a thing called Nosema ceranae, which is, it's a microsporidian parasite that originated in the Asian honeybee, a different species of honeybee naturally found in Asia, but it's spread around the world probably with honeybees that were taken to Asia and then became infected and then have been shipped elsewhere, we're not entirely sure. But that will happily jump from honeybees into bumblebees and it's been detected at fairly high frequency in wild bumblebees in Europe. We don't know exactly when it got here, we don't really have much clue how many bees it's killing but in the lab it can be fatal. So it's kind of concerning that this you know, Asian gut parasite is, somehow got itself from Asian honeybees in China to British bumblebees flying around here you know.
Art Woods 25:04
So in terms of mechanisms for cutting down on the spread of diseases, it seems like the obvious thing is to not move bees around nearly as much. So are there programs to try to cut down on these movements, do you favor much stricter restrictions on what you know where people can take their colonies?
Dave Goulson 25:25
So one thing we haven't mentioned actually is the, which has got to be in there because it's a really interesting new ish angle on this is that we've also started commercially rearing and shipping bumblebees around the world, which is exacerbated the problems we'd already created by shipping honeybees around the world.
Art Woods 25:43
And that's because they're better pollinators for some things?
Dave Goulson 25:46
They're really good at pollinating tomatoes is the big product because that needs buzz pollinating and honeybees are useless at buzz pollinating so they don't even visit tomato flowers. Other Solanaceae also, and there's other plants too, but tomatoes is the big one. So it's usually for glasshouse use, but bumblebees, someone in the Netherlands actually a guy who was a vet strangely, but he worked out how to breed bumblebees in the late 80s and set up a little factory selling them and it quickly became a global business with huge factories churning out literally millions of bumblebee nests, and shipping them around the world. But the bumblebees are reared on pollen collected by honeybee keepers who make money by sticking pollen traps on their honey bee hives and then supplying the pollen to the bumble bee factories. So you've got this horrible, horribly efficient mechanism for taking honeybee diseases and giving them to bumblebees, and then shipping bumblebees all over the world. And there's really no regulation of that trade at all. So we know that you know they're shipped from Europe to, they've been taken to the Americas.
Art Woods 27:03
Is there any prospect for regulation or is it, there's just no way? It's not gonna happen?
Dave Goulson 27:07
Not, it doesn't seem likely, it would it really needs international agreement. You know, many, so the US for example, and Canada no longer allow importation of non native bees, so you can't buy a European bumblebee nest and take it to the states anymore. But the factories will sell them to anyone that'll buy them, as far as I can tell. They don't seem to have any scruples whatsoever. So we know for example, they were they sold European bumblebees to Chile in 1998, and now there's an invasion of South America by European bumblebees carrying European bee diseases, which have had a really disastrous effect on, there's a beautiful, the only bumblebee native to the bottom half of South America is the world's biggest bumblebee, Bombus dahlbomii. Giant ginger thing, it looks like a flying mouse I'm told, I've never had the pleasure of seeing one. And it used to be really common in Chile and Argentina. But it's teetering on the edge of extinction because it's been wiped out by the, seemingly by the diseases being carried by these European bumblebees. So it's really tragic. And you know, entirely predictable. I mean, you know, 1998 wasn't that long ago, we surely knew better than to just introduce a new species to a new continent without even thinking to check its health. It's just ridiculous. And it could happen again tomorrow, you know, because nobody's, there's no law preventing it.
Marty Martin 28:42
Dave a minute ago, you raised a really interesting point and maybe to turn to the pesticide issue, that the effects of these diseases may be exacerbated when the parasites and viruses whatever it might be, are showing up in contexts where things like neonicotinoids are also being used. What how much do we worry about? What do we know about pesticides and bumblebees and honeybees?
Dave Goulson 29:05
Yeah, I mean, there's really clear evidence. It's funny, this is hugely controversial. It's the one area of, kind of, bee science where there's massive controversy, because of course, there's a lot of money at stake. For me, I think it's completely clear and obvious that current pesticide use is contributing to bee declines. There's an overwhelming body of evidence. Some pesticides are worse than others. neonicotinoids undoubtedly among the more harmful ones, but we shouldn't get completely focused on neonicotinoids. You know, there are there are 500 different pesticides used in Europe and I think nearly twice that many used in North America.
Art Woods 29:50
Not surprising.
Dave Goulson 29:51
Yeah. And you know, many of them are probably harmful to bees, depending on the circumstances and, but you know, the problem is, of course, there's a strong vested interest in disputing this. And there are, you know, industry itself, but it's very similar to the to what happened with tobacco in the 20th century. I think it's the best way I can explain it.
Art Woods 30:16
Confuse and deny.
Dave Goulson 30:16
Exactly, kind of smoke and mirrors, publish counter claims, you know, get your own scientists to dispute every piece of evidence that suggests pesticides do harm bees, to produce counter evidence to make it seem like there's there's a controversy when actually there isn't really a controversy, which makes it really easy for politicians to avoid doing anything, because they can say, oh, well, you know, we need a bit more research, you know, the scientists can't agree. Yeah, so it's frustrating. And it's really, I mean, it's also really interesting to see to how it plays out, you know, that different parts of the world can look at the same body of evidence and come to quite different conclusions, seemingly, you know. The European Union, put a lot of had a, a team of scientists basically investigate neonicotinoids. And they spent about a year doing it and wrote this enormous report, which basically concluded that neonicotinoids pose an unacceptable risk to bees, is how they put it. And so the European Union banned them or banned most of them. But, you know, the rest of the world disagrees, seemingly, you know. In the United States, they're still obviously widely used, and no signs at all of any serious restrictions on their use. And yet, you know, you guys can see the same academic studies that we can see, so it's kind of interesting, but you know, different conclusions are drawn, but. Yeah, well, different vested interests too right. Just, I want to stick on pesticides, just for another minute and ask, I was really amazed by something you said in this 2015 Science Express paper of yours about just the total number of pesticides that have been detected in in honey and in honeybee colonies. It was like, you know, more than 100, I think, and that raises this issue of, people do studies, but they often do studies on single compounds, right. But the bees often are exposed to cocktails of these things that may have interactive effects. Is there anybody who's grappling with this interactive effect problem? We've tried, and I'm sure there are others trying. It's just one of those things that's really intractable experimentally, you know, because there are so many combinations of chemicals and concentrations. Yeah, your experiment blows up to some you know to some giant hyper volume, right?
32:44
Yeah, you can just about cope with two. But, you know, as you say, the reality is, you look in the honey or pollen in a bee nest, and, you know, commonly find 10 15 20 different pesticides. And, you know, where do you, and every nest has a different combination, depending on where it's been, you know, where they've been foraging. So it's a nightmare. And we also, you know, the regulatory process is fundamentally flawed for this same reason, because it studies one compound at a time, you know, if you bring a new compound and you want to get it licensed to sell to farmers, you have to show that that particular product doesn't kill a honeybee in a lab test. But you obviously don't expose it, you know, that's a really healthy honeybee.
Art Woods 33:34
But what about that one with the other 100 pesticides that they're exposed to you, right? Yeah.
Dave Goulson 33:38
Yeah, so and the scale of exposure is really staggering. I mean, the more recently than than that, we, after we published that 2015 paper, there was a report that came out of a Swiss research group where they, it is really an interesting kind of bit of citizen science approach. They, they put out a call for people who were going on holiday to bring them back a honey sample from wherever they were going in the world. And they analyzed them, they were only, they only looked for neonicotinoids they didn't look for any other pesticides. But 75% of samples from all over the world contain detectable levels of at least one and sometimes up to five different neonicotinoids in a single sample. And you know, this included islands in the middle of the Pacific, you know, really remote corners of the world where you think God, you know, even there these poor bees are being, and then given that these are neurotoxins that are really phenomenally toxic, and often the concentrations being found in honey were higher than concentrations that are known to have sometimes lethal, not, let alone sub lethal effects on bees. Then, you know, we shouldn't really be surprised that insects have problems really because, I mean, I guess the important point is here that if honeybees are being exposed, it means that all flower visiting insects are being exposed. So and that's, that's 10s of 1000s of species.
Art Woods 35:10
We haven't talked too much yet about the consequences of declines in bees for the rest of the world, and maybe let's just turn now to that for a few minutes and start with what we might term the pollination crisis, right. So obviously bees are important for pollinating lots of crops in the world. They're also super important for pollinating lots of wild plants. So what are the effects of these observed declines on on pollination services?
Dave Goulson 35:41
So there is, there's clear evidence that some crops some of the time are having their yields reduced, because there aren't enough pollinators. There are a few, well, one really famous example, which is often cited of, in southwest China, where they now commonly hand pollinate apples and pears, there are huge areas of apple and pear orchards there.
Art Woods 36:07
You said they're hand pollinating because there's not enough pollinators.
Dave Goulson 36:10
There's not enough pollinators, not enough wild pollinators to do the job. And I've seen it in India as well, where in northeastern India, near Calcutta, where they, farmers are now hand pollinating squash plants, because they, they're just not getting pollinated unless they do it themselves. And then there's been some big scale studies looking at crop yields around the world and comparing insect and wind pollinated crops and how yields have changed over time. And there's, there's pretty good evidence that we are, you know, on the edge of a crisis, where yields are going to be depressed more and more, because there aren't enough pollinators to go around. So, you know, clearly, that's a worry, because three, three, roughly three quarters of all the crops that people grow, need pollination to varying degrees. You know, some can produce quite a lot of yield without any pollination, some produce nothing. So there's a whole spectrum there. And it only, so, although it's three quarters of the crops by species, those crops only produce about a third of our food by weight, because the the wind pollinated grasses make up the bulk of our diet. And if you then take into account the fact that some of those insect pollinated crops will actually produce a reasonable yield without pollination, actually, it's something like 10, or 8 to 10% of our food globally, is dependent on pollinators. But that's still quite a lot of food. And it's the healthiest chunk of our diet. You know, so right now, globally, if you look at diets and what, human nutrition in relation to what we grow, we grow way more cereal and oil than we need to feed everybody. But we don't grow enough fruit and veg to give everyone a healthy diet. So even if it was completely fairly distributed, there aren't enough fruits and veg for everybody. So if you were to take away, Sort of junk junk food on a global scale here. Yeah, yeah. I mean, that's why, you know, our diets are dominated by processed starchy foods, you know, pasta and bread, cake and biscuits and pies, and pastries and so on. It's all because it's all come from, it comes from cereals, basically. And we've got loads of those. But we don't have enough, you know, apples and tomatoes, and so on, which are the things that need the insects.
Art Woods 38:43
So in terms of pollination by honeybees versus wild bees, you guys are and others have evidence that wild insects and wild bees in particular are particularly important, right?
Dave Goulson 38:55
Yeah, I absolutely. I mean, it varies crop by crop. And so it's hard to generalize. But there is this kind of common misconception out there that the honeybee pollinates all of our crops and with that, you know, we don't need any of the pollinators at all, which is absolute rubbish. So in the UK, there was an analysis done of this, and it concluded that honeybees contribute a maximum of 30% of crop pollination.
Art Woods 39:26
Yeah, that's amazing. My intuition was it was way higher than that.
Dave Goulson 39:29
So you know, the bulk is being done by these wild insects that nobody looks after at all that we just assume are going to turn up and obviously the worrying thing is that they're not anymore.
Marty Martin 39:39
So let's let's try to put a positive perspective on some of this. There are some things we've already talked about having gardens if you're living in the cities, I mean, there are positive, potentially positive impacts. But if you're an individual landowner, I mean, what are the kinds of behaviors that are most promising to have the positive impacts we look for?
Dave Goulson 39:59
So just to go back to the gardening thing, I mean, actually, I although we've talked about it briefly, and gardens on average are not bad for bees and other insects, I think there's a huge potential there for them to be much better and for us to do a lot in urban areas to, to make them into, you know, as biodiverse as possible because there's not, there's not really much of a compromise to be made there, you know, there's not a big downside to making our gardens and our city parks and so on more insect friendly, we're not sacrificing food production or anything like that. The only compromise really is we have to persuade people to maybe accept things looking a bit different, you know, instead of mown grass, tall flowers, that kind of thing. But, you know, given that the number of people is set to continue, the probably the the extent of urbanization is going to expand globally, it seems like a kind of an easy win option to try and promote conservation of insect life and biodiversity generally in urban areas. And it's something that people are kind of buying into, you know, there's already people, you know, planting their gardens full of bee friendly flowers, butterfly friendly flowers, garden centers, market plants, with bee logos as one, you know, pollinator friendly plants, and so on. So there's a whole industry there springing up. And I think it's a bit of an open door that, you know, it's one of my kind of, you know, passions, I guess, is, is trying to promote that as one way we can help to combat insect declines. And it's a nice one, because it's something everyone can get involved in, or at least everyone that's lucky enough to have a bit of a garden. And, you know, unlike many of these big kind of doom and gloom environmental stories, you know, climate change, or the rain forests on fire in Brazil, or whatever, you know, at least with insect declines, you know, people can actually do, they can plant a lavender in their garden, or whatever it might be, and they can see it, you know, within, literally within five minutes, you'll see bees sniff it out and start feeding. So you know, people can, can feel they're doing something useful. And, and also, it's a kind of way of maybe getting people to reconnect a bit with nature, you know, inviting nature into our cities. So I think that's really cool. But the bigger issue is, what do we do about the rest of the world? The bits that aren't gardens? Well that's a thornier issue. So we talked a bit about you know, that there are agri environment schemes that are available to help farmers make their farms more insect friendly. But thus far, they're not not been hugely successful.
Art Woods 42:43
It just seems like given the fraction of pollination that's done by wild insects, that everybody's interests ought to be aligned in some way for promoting insect diversity, right? I mean, the farmers have a vested interest in doing that. So, you know, let's do that.
Dave Goulson 42:57
Yeah, I mean, I think they have and, I mean, there was, so there was a really interesting paper published, I think it was five years ago, by Richard Pywell, and folk from a UK government lab, the Center for Ecology and Hydrology, where they did a big farm scale experiment where they got farmers to, to take out, it was either 3% or 8% of their cropped area, and set it aside for biodiversity, most of it went into flower strips. And they looked at the economics of the farm and the crop yield they got and so on. And, and the farmers who took 8% of their crop land out of production in the first year or two, they got a slight reduction in yield, of course, because they were farming less land. But after five years, the yield was exactly the same, it had gone back up to the same as it was in the farms that hadn't taken any land out of production. And I thought that was really interesting. They put it down to a combination of better pollination and better pest control from natural enemies coming out of these, these nature areas. But if you if you believe that,
Art Woods 44:08
So with 8% less land then you're producing just as much crop?
Dave Goulson 44:13
Yeah, I mean, so it's also worth kind of noting that they, obviously, they let the farmers choose which bits to take out. And the farmers inevitably chose the least productive bits, which is obvious. So they weren't losing 8% to start with in terms of crop yield, they were considerably less than, you know, it was the crappy sort of corners with poor soil and so on. But I thought that was really I mean, you know, the take home message from that ought to be that every farmer can take 8% of his land out of production and plant it full of flowers, and he won't lose any money at all. And, I mean, you know, whether you can safely extrapolate I don't know but anyway, that it would be nice to think you could and certainly it seems, seems that avenue we should, we should investigate more. But you know, that sort of just languishes in, you know, Proceedings of the Royal Society. No farmers paid any attention to it, no government policymaker seems to have noticed, you know, but yeah, I think it would be possible to farm in a much more, you know, it's a, it's a cheesy thing to say, but we need to kind of work with nature rather than, you know, keep trying to kill everything and control everything. And that sounds unscientific. But I think the basic idea that, you know, if you tried to grow a crop, it's like a vacuum. If you try and kill everything, you know, you try and eradicate all the pests, then it's not a sensible strategy long term, because it you know, the pests will evolve resistance, you're wiping out all the natural enemies, you're wiping out the pollinators, it doesn't make sense. And yet, that's where we are, it seems it's, so we need, you know, we need a bit of a rethink. But it's hard to hard to do.
Art Woods 46:05
Well, Dave, hey, we've been talking now for about an hour and 15 minutes, and I want to start moving toward wrapping it up. We have a couple of sort of big forward looking questions here at the end, we'd like to talk over with you, and one of them is just to, to maybe ask you to lay out your vision for what we need to do going forward to actually monitor, you know, in the UK and US around the world, and actually establish with more certainty what's happening with different species and different groups of insects. And so I guess this is the, you know, imagine you have millions of dollars to spend on designing a study to do this, what would you do?
Dave Goulson 46:47
It's really challenging. And, so I'm really conflicted as to the best way to monitor insects. There was there was a paper published a few years ago, which suggested that, for example, pan trapping, is probably one of the better ways you might do it, obviously doesn't capture all insects, but it's good for at least flower visiting insects. And it's very easy to do in a standardized way. And it's something that almost anyone can put out pan traps and collect them in again. And as long as you've got the resources to pay for a team of people to identify the contents of the pan trap, then that's actually a, you know, relatively speaking, cheap and effective, standardized trapping system monitoring system that could be rolled out on quite a big scale. We actually tried setting up our own citizen science based pan trapping scheme in the UK a couple of years ago. There are some logistical problems, not least of which is you're not allowed to post bottles of alcohol through the post in the UK.
Art Woods 47:56
Fundamental problem for science.
Dave Goulson 47:59
Yeah, so we ended up asking people to post, pickle the insects in vinegar, because that you can put that in the post, but it didn't work as well as alcohol. And we ended up with these rather disintegrated insects samples. I think that has potential. And it it offers lots of advantages compared to anything else I can really think of. Although obviously, it doesn't encompass, you know, ground beetles or many other insect groups. But I'm also a bit bit worried about lethal trapping. I didn't used to be I mean, I, you know, an entomologist for a long time, I've been very gung ho about, for example, the, the German study, which the Krefeld study, which showed this,
Art Woods 48:44
Is this the Hallmann et al. paper?
Dave Goulson 48:46
Yeah. 76% decline over 26 years in German nature reserves. That was based on malaise trapping, and that study collected 50 kilos of insects.
Art Woods 48:57
So the monitoring itself is contributing, perhaps, yeah.
Dave Goulson 49:01
I mean, I, I'm pretty sure the monitoring actually has negligible impact. You know, on the scale of Germany, 50 kilos of insects is probably nothing, but I think I'm getting soft in my old age, but I really,
Art Woods 49:17
You're tired of killing insects, huh?
Dave Goulson 49:19
Well, yeah, I think that's basically it. And I also think it kind of sends the wrong message. You know, if we, if we want people to engage with insect conservation, do we really want to tell them to stick pan traps and drown a whole bunch of bumblebees and other pollinators in their garden? I'm not sure the knowledge we would gain is actually worth the, you know, that kind of effect it might have on I don't know it just the whole thing. It doesn't sit well with me anymore.
Art Woods 49:50
Yeah, it's like, you know, what museums used to go out and kill birds to get them into the trays right. And we don't do that anymore.
Dave Goulson 49:56
Yeah, well exactly we've all had to change and the world is changing. And I think if we want people to respect nature more than they currently do, and to, you know, kind of really live more, you know, tread more gently on the planet, then then promoting mass trapping of insect schemes is maybe not the way forward.
Art Woods 50:19
So if we get back to the sort of grand vision for monitoring, what would you do in the tropics, right? So we know a lot about Europe and the US, how do we figure out what's going on in the tropics?
Dave Goulson 50:31
With enormous difficulty. No, honestly, I don't have a grand vision as to how you could do that. I mean, it's the logistics of it are so intractable, I mean, sure, you could pick a few groups, you know, I mean, the things that do work, if you if you could recruit local volunteers or pay for it to be done, you know, you can walk a transact, and count butterflies even in the tropics, that would be, it would be challenging, because obviously, there are many more species, but it could be done, I think it's just about viable. So you could choose a few, a few groups and focus on those and try to use them as an indicator species. You know, it would be a long, long way from ideal. But but it would be a start, it would be better than the no data at all situation we're in at the moment. You know, I mean, and, and honestly, the sooner we started, the better. Because, you know, it's like planting a tree, the best time to do it is was 20 years ago, but failing that, do it today, you know, and but it's so difficult to get anyone to fund long term monitoring, because, you know, it's, there's no interest for the first decade, it doesn't tell you anything, you know, so our whole funding model doesn't, isn't built around long term research, sadly. Certainly in the UK, you can never get grants for more than three years, so.
Marty Martin 51:53
What about technological innovations? How much is is environmental DNA? Are those approaches being used to try to at least find out who is where getting the numbers is, of course, more difficult. But is that something that's becoming common?
Dave Goulson 52:06
It certainly, as I understand it, and it's not, you know, really my area of expertise, but it seems to have huge potential. But my understanding is you really need to, you know, you need to have genotyped your every species that might be in your sample first before you can then search for them. And obviously, for, you know, most insects, and particularly in tropical regions, you know, nobody's taken a DNA sample. So until that is done, and when there are millions of them to do that's obviously kind of quite a challenge. It's been applied in looking at pollinator behavior and where they're collecting their food by looking by identifying the sources of pollen that bees are collecting. And that's really nice as a way of looking at quantifying pollination networks, and seems to be quite quick and effective. So in theory in the future, I guess, as these things become cheaper and faster, it could be pretty powerful.
Art Woods 53:07
But so as I understand it, nobody is going out and looking and collecting flowers, and then scraping bee DNA off of those and identifying what's visited them.
Dave Goulson 53:16
No, I don't, I doubt it, who knows. I mean, I, I find some of this environmental DNA stuff blows my mind. The idea that you can take a little water sample from a pond and detect whether there's a newt somewhere in that pond, you know, clearly. Is there so much newt DNA just sloshing around? But yeah, theoretically, I guess that that kind of approach might might work wonders in the future if there's anything left to monitor by the time we get that far.
Marty Martin 53:45
So Dave, we really appreciate your conversation. I wish the topic was a little bit more exciting. Not that it's not exciting, but to be to be depressed is never where we want to leave the audience. So here's your opportunity to inspire us in any way you want. The last question we ask our guests is what did we not give you the chance to say? Regarding conservation, regarding your own research, ways forward? Anything you'd like to say?
Dave Goulson 54:10
I'd like to say two things if that's all right, just like I started off with two. One of them, I've already said but I'm gonna say it again, because I think it's really important that people can get involved. You know, plant a flower, stop using pesticides in your garden, make a compost heap, dig a pond, there's there's reams of information out there about how people can can make their own little patch insect friendly, and it's really rewarding and fun. And if everybody did it, it would help. But big, big picture, I'm quite inclined to think we need to try somehow to completely change the way we grow food and free up huge amounts of land for rewilding projects. You know, the EO Wilson half Earth approach. We have this food production system at the moment which is completely bonkers, it does enormous environmental damage, it contributes massively to climate change, soil erosion, biodiversity collapse. And we throw away a third of the produce that we grow in the world, we feed way too much to our animals, we eat too much meat, the whole system's crazily inefficient. And if you actually could somehow coordinate a redesign of our food production system, you could you could feed the world easily with a small proportion of the existing farmland, and turn over vast tracts to nature. And that's what I'd really, really love to see. Of course, you know, it's pie in the sky. But theoretically it's possible. And if we're really going to, you know, save the planet so that future generations get to appreciate this amazing biodiversity that we have, then then we have to think big, and I'd love to see us somehow finding a way down that route.
Art Woods 55:51
I'm inspired.
Marty Martin 55:53
Yeah, that was inspiring. It was good. That was a great way to end. It is possible. It's difficult, but it is possible.
Art Woods 56:10
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Marty Martin 56:21
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Art Woods 56:35
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Marty Martin 56:44
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Art Woods 56:59
If you're looking for even more big biology content, and who wouldn't, you should check out our playlists on Spotify. We're grouping together episodes by topic and organizing them into themed playlists. Our first playlist is all about evolution. We'll have a link to the playlist in the episode description and we hope you check it out.
Marty Martin 57:15
On our next episode, we talked to Rob Raguso, professor of biology at Cornell University, Rob studies coevolution between insects and plants, and we talk with him about the crazy outcomes from coevolutionary dynamics, as well as the roles that coevolution plays in generating ecosystem services.
Rob Raguso 57:32
Competing for bats drove agaves to this kind of, you know, almost suicidal production of of giant candelabras of flowers. And because they're desert plants, right, and there can plants they can only do photosynthesis. They can only like fix carbon at night. They can't grow very fast. They're limited by their form of photosynthesis and by the severity of the climate in which they live you know. So basically they've been driven to be like salmon where they can only afford one explosive reproductive you know bout and then they die.
Art Woods 58:08
Thanks to Matt Blois and Ruth Demree for producing this episode. Jordan Greer, Ajinkya Dahake and Dana Baxter manage our social media channels and help produce the podcast. As always, Steve Lane manages the website.
Marty Martin 58:19
And thank you to the College of Public Health at the University of South Florida. The College of Humanities and Sciences at the University of Montana and the National Science Foundation for support.
Art Woods 58:27
Music on the episode is from Podington Bear.