Is Global Bee Diversity Declining? (Ep. 6)

The fact that many bee species are in danger isn’t news to most. Bees play a considerable role in ecosystems and biodiversity because they, and other insects, are responsible for plant pollination. In this episode, we look at an important study that found between 2006 and 2015, about 25 percent fewer bee species appeared in the reviewed data compared with the period between 1946 and 1995.

Dr. Eduardo Zattera is an Argentinean biologist with a Ph.D. in Behavior, Ecology, Evolution, and Systematics from the University of Maryland, College Park. Having worked at the Smithsonian Institution National Museum of Natural History and Indiana University, Bloomington, he is currently a staff researcher at CONICET, a professor at the National University of Comahue, and a member of the Pollination Ecology Group at the Institute for Biodiversity and Environmental Research in Bariloche, Argentina. His research interests include developmental evolution, genomics, ecophysiology, and the conservation of native bumblebees.

Bee number decline has primarily been based on local or regional studies. This was one of the first looks at the global status of bee decline. You can read Eduardo’s study here. 

Eduardo is currently leading a citizen science project on bumblebee sightings in Argentina. (In Spanish.)

Did you know?

Eduardo talked about the “flying mouse” bumblebee. The Giant Patagonian bumblebee can measure up to 40mm and is a striking orange color. Its decline began with the introduction of European honeybees for commercial pollination. It’s a vital pollinator for native plants found in its home range of Chile and Argentina. 

Transcript

[00:00:00] How are the bees doing? This is a critically important question, and one being studied by researchers worldwide. However, without historical data, is it possible to know if the global abundance in bees is in fact decreasing? We’re going to try and figure it out with today’s guest, Dr. Eduardo Zattara. He and his colleague looked into global trends in bee diversity since the 1920s, using data gathered into a publicly available database by the Global Biodiversity Information Facility.

Let’s talk to Dr. Zattara. Can you share with us the backstory of your study on changes in bee diversity over time? Right. So before you start with the number of actual individual bees, you have to support how many different species [00:01:00] we have. And there’s been, beyond the honeybee, there’s like wild bees and wild bees are estimated to be around 20,000 species that have been described so far, and so

we were interested in trying to estimate, not so much how many there are, but whether they have been changing in their diversity. How many species are we seeing these days compared to how many species we used to see several years ago? This has been an important issue for quite some time, and it’s really, it’s not only for bees, actually, it’s something that’s happening for, you know, most of animal and plant biodiversity

worldwide as we know we’re having an impact as humans on our natural world. And so this, this big question about insects in general and about bees in particulars about how they’re doing. We know the environment’s been degrading quite a bit in the last few decades, so [00:02:00] we wanted to know how well are bees doing.

And our first measure of how they’re doing is, you know, are we still having the same amount of species we used to have 50 or a hundred years ago? And that’s where it all started. There had been no work trying to tackle this question, which is a hard question. It’s hard to measure today, and it’s very hard to measure what happened.

I mean, if you haven’t measured before, then how do you know what to compare against, like what’s the baseline? So you looked at both the abundance and the diversity of bees in each location. Can you explain why it matters that not only do we have a lot of bees, but we have a lot of different types of bees?

Well, the thing is that, you know, some species are very abundant. We probably know by now, and thanks to our own handling of them, honeybees are the most abundant everywhere. But then there are some species that are [00:03:00] also much rarer. And the thing is that it’s easier for our rare species to actually, you know, become rarer to the point of extinction than it is for a very abundant bee.

And so it’s not just about how many species we have. Different species have different roles and you know, they fulfill different functions in the ecosystems. And a rare species might have a very important function that more abundant species might not be able to fulfill. So that’s why it’s not only amount of species, but how many of each are there around, and some species are normally rare, so it’s okay for them to be found in very low abundance.

They probably use very specific resources and you know, they will never be abundant. So how does the decline in bee numbers affect biodiversity? Well, we [00:04:00] know, we know for bees and for almost every species that normally species, you know, are adapted to specific ecosystems and they fulfill a role and other species are adapted to have them around.

This is especially obvious for pollination. So different species of bees will pollinate different types of flowers. And so, a flower, that’s pollinated by a very specific type of bee might run into trouble if that bee goes away. And so animals that depends on those plants are also in trouble because if the plant’s in trouble, because the bee’s in trouble, then you have animals in trouble.

That’s sort of cascades through the ecosystem and might lead to very, you know, drastic changes. And on the other hand, it might be that what one bee is doing can be done by a different species of bee. So one bee species for [00:05:00] some reason goes down in abundance, but then another species that’s now more abundant will fulfill its role.

So it will depend on the bee species. It will depend on how, you know, other species depend on, on that species where they really need that one species, or they can take several different type of species, and that’s a very complex network of interactions that is part of what we do also, we try to tease out, what plants interact with which bees and you know, which ones interact with more than one bee, and which ones are very specialized in a single type of bees.

And the other way around which bees really depend on one type of plant or can use several different types of flowers. And that gives us a better picture of what are the bees that are more fragile. And also what are the bees whose disappearance will leave a more fragile environment. [00:06:00] Do you have a favorite bee?

Oh yeah. We do a lot of work on bumblebees and we have our favorite bumblebees. And why bumblebees? Well bumblebees are big. They’re very large. They’re the easiest to recognize among bees. They also have very interesting traits. You know the closest thing insects have to warm bloodness so they can regulate their internal temperature.

They have societies, but they have very simple societies. They’re not as complex as, you know, the honeybee societies, but they do have queens and they have a worker bees and they have drone males. They’re very interesting because somehow, um, the more basic society that they build, but they still build societies and also that they are annual.

So their colonies will start at the end at the onset of spring. And by fall they mostly die down and only the new queens will survive and hibernate [00:07:00] to make new colony in the following year. So they’re very interesting on the scientific side because it simplified many questions about bees and bee evolution. But they are also large and fuzzy, and they make noise.

We have an endangered species in Patagonia, there’s only a single native species of bee, which has become endangered since production of uh, two species of European bumblebees and for an insect, it’s amazingly charismatic. It’s really easy to bring people attention about the plight of this particular species. People have more sympathy for this insect that then you will expect for other types of bees, and so they make a very, you know, easygoing study subject and it makes it for an easier target for conservation.

And what’s the name of this bee in Patagonia? Scientific [00:08:00] name is Bombus dahlbomii or dahlbomi. Okay. And it’s called a giant Patagonian bumblebee, sometimes also called the flying mouse. It’s one of the largest, if not the largest. Is it that big? It’s probably not as big as a mouse, although I would think that the largest queens might be almost the sizes of the smallest mice.

It is quite large. It’s larger than most bees that you will see in Europe. Beautiful. So what do you believe are the main reasons for bee decline and is there anything we can do about it? So the main reasons are about the same that are causing decline of almost everything else is human activities. And you can think about it in changes in land use.

So we are removing natural habitat for them and replacing them with a lot of habitat that’s mostly agricultural and that’s not very bee friendly, especially for bumblebees. [00:09:00] Another big issue has to do with climate change. So most bumblebees are temperate cold species. And so they tend to be well adapted to specific phenology of plants that depend on weather.

And when you have climate change, you have a change in the time of flowering. And then you have mismatches between the time of flowering of the plants they need and the time they emerge from a hibernation. And so that’s a problem too. But we think the biggest issue at least for this one species has to do with moving around species.

So we move around honeybees and we move around bumblebees, and then we move around a lot of other species, and that also makes a big impact on bee species. So that’s our main issue for the giant Patagonian bumblebee, because with the entrance of European bees that were brought for agricultural purposes, they brought in parasites and diseases that they didn’t know, and that hit them very hard.

But then, in [00:10:00] general for wild bees the problem is that we are basically taking away their natural habitat and replacing with farming fields. And not only that we are also, uh, spraying those farming fields with a lot of pesticides, and that’s very bad for bees. So you have pesticides that just kill the bees and then you have pesticide that don’t kill the bees

but oftentimes it affects a lot of their behavior, their physiology. And so they’re not dead, but they’re performing poorly, and that means that on the run it’s as good as dead. So what can we do? No single action can change the way they’re working these days. We have a strongly capitalistic driven economy. We are just sucking up all of the world’s resources very rapidly and without thinking how we’ll replenish them.

And that needs to [00:11:00] solve that we need a change in mindset. We need a strong change in policy and we need to, you know, try the best, we have to go political into that. We have to go into activism. We have to think when we vote. Individual elections have to affect higher level ways of humanity conducting their business.

We have to change that. But then there is small things we can do to help. We can think of it better about not only environmentally friendly practices, but also if we have a garden, we wanna think about what we do with your garden. Do we want just like a perfectly manicured green herb free, uh, lawn? Or do we wanna have, you know, something more close to what was before?

You know, like a more like a meadow. We have to plant flowers. Try to think about having flowers that are closer to the native flowers rather than just nice garden varieties that might not be very [00:12:00] useful to bees, to think about having a variety of flowers that will be flowering throughout the year if possible.

Keep in mind that a lot of these garden plants tend to be toxic to many insects and even though they have nice flowers then and not be attacked by a lot of people know what you think of as garden pests, they actually might be poisoning the pests, but also the bees that try to visit them. So all those things, and there’s a ton of information around because there’s a ton of, you know, love for bees that’s spreading around last decade or so.

And that helps a lot because it’s much more aware about, you know, being environmental friendly and being bee friendly. And that helps a lot. But that has to go alongside with thinking about higher level policy and, and what we do when we go and put a vote or support one, uh, way of doing things or [00:13:00] the other.

Fantastic. Thank you so much. You are very welcome, Jacy. Bees are in trouble. As Dr. Zattera said, we need to take a serious look at habitat destruction, make sure we’re implementing environmentally friendly practices in agricultural and urban settings, and provide plenty of flowering options for our own native bees.

Thanks so much for listening to today’s episode. I appreciate your time. If you’re enjoying The Bee’s Knees, it would mean a lot if you would follow the show, leave a review, or tell a friend. Don’t forget to visit the website, the bees knees.website for our show notes, transcript, and more details on the fabulous Patagonian bumblebee.

Until next time, keep buzzing.