The Buzz On Native Bees In Your Neighborhood
When you think ‘bees,’ you probably think of a neat stack of white hive boxes and the jars of honey on the store shelves. But there’s a lot more to bees than the agricultural staple, the European honey bee. Around the world there are over 20,000 known bee species, and around 4,000 of them are native to the United States. While these native bees play a key role in pollinating our plants and ensuring the health of ecosystems, they don’t get a ton of recognition or support.
Around three-quarters of flowering plant species rely on insects for pollination, and some native plants have evolved a partnership with specific native bee pollinators. Squashes, pumpkins, gourds, and the annual sunflower all have specific species of native bees as part of their life cycles. Native plants such as blueberries, cherries, and cranberries all developed without the European honeybee, which arrived in North America in 1622.
Dr. Neal Williams, a professor of entomology at the University of California, Davis, joins Ira to talk about native bees, bee behavior and pollination.
Dr. Neal Williams is a professor of entomology at the University of California, Davis in Davis, California.
IRA FLATOW: This is Science Friday. I’m Ira Flatow.
When I say “bees,” you probably think of a neat stack of white hive boxes and the jars of honey on the store shelves, right? But there’s a lot more to bees than that. Because around the world, there are over 20,000 known bee species, and 4,000 of them are native to the U.S.
And while these native bees that live in the wild play a key role in pollinating our plants, they don’t get a ton of recognition or support like the ones that live in a box.
Well, joining me now to talk about our native bees is Dr. Neal Williams. He’s a professor of entomology at the University of California, Davis, where he studies bee behavior and pollination.
Welcome to Science Friday.
NEAL WILLIAMS: Thank you, Ira. It’s great to be here today.
IRA FLATOW: Nice to have you. Let’s get this straight from the beginning. There are bees that live in the colonies in the white boxes and bees that don’t live in the boxes, but in the wild, right?
NEAL WILLIAMS: That’s certainly one good way of thinking about it. There are other bees that live in colonies as well, in addition to honey bees, which are wild or native bees in the U.S. But they are, again, different from what most of us think of, which is the European honeybee. Which is an introduced species that we manage for our own purposes.
IRA FLATOW: So the honey bees we have, they’re not native bees. We brought them here from Europe.
NEAL WILLIAMS: That’s right. The bees that we use for producing honey or for assisting with pollination and agriculture, they were brought over in Colonial times and have been in the U.S. ever since.
IRA FLATOW: OK. So let’s talk about the native bees. How many of them do what people might call normal bee things like visiting flowers for nectar and pollen?
NEAL WILLIAMS: So really, all of those species do that sort of normal bee thing. And in some ways, to visit a flower is part of what’s defining a bee. Because bees are insects that essentially get their food resources from flowers, either the pollen that flowers produce or the nectar they produce, and in a few cases things like oils as well.
If we think about where they fit in the grand scheme of the insect world, they’re basically a branch of the wasp that have switched from being meat eating, from being carnivores, to being herbivores that feed on these particular parts of flowers.
IRA FLATOW: OK. So introduce us to some of them. What bees would we be seeing around us– bumble bees, things like that?
NEAL WILLIAMS: Absolutely. So bumblebees are probably among the most familiar non-honeybee bees that we have in the U.S. There are some others that our listeners in the East will be very familiar, the carpenter bees. They’re large bees, the same size as bumblebees, more or less, and often are living in existing wood.
We have dwarf carpenter bees that are tiny varieties of the same group of bees. We have mining bees, which are bees that burrow into the ground in the soil. The science-y name is Andrena. There are a lot of spring bees in that group, but they’re ground nesters.
We have the mason bees and the leafcutter bees. Those are bees that generally nest in existing tunnels, either above ground in wood or sometimes below ground. And as their name suggests, the mason bees are building their nests partly out of mud, which then dries.
And the leafcutter bees are chewing pieces of leaves and making their nests out of those leaf pieces, either as whole chunks of leaves or as chewed up bits of leaves. We have a series of other small to large bees that nest on the ground or nest above ground that fall into other families. But probably those are the most familiar for most people.
IRA FLATOW: Interesting. You said they all visit plants. Are they any better or worse at pollinating than the honey bees?
NEAL WILLIAMS: Yeah, that’s an interesting question. And we just recently now have a very large summary of that comparison that compares the quality of honey bees at pollinating flowers versus the quality of other bees. And in general, we find that honey bees are sort of equal or slightly less good than many other bees.
And the old adage, the jack of all trades is the master of none– the honeybee is really that jack of all trades. It’s very wide in the number of flowers that it will visit, but doesn’t tend to be particularly effective on any one flower visit relative to some of the other bees we have.
IRA FLATOW: Some farmers bring their hives of honey bees to their fields or their orchards to help with pollination. Are there specific crops that the native bees are better at pollinating?
NEAL WILLIAMS: The honey bee is particularly useful because it can be moved around and it lives in these very large colonies. So it’s a highly valuable agricultural pollinator. But there are a number of crops for which, if we look on the basis of an individual bee, the native bees are actually quite a bit better.
A really great example of that would be alfalfa. And although we don’t feed alfalfa seed to animals– I mean, that’s a main forage for cows that we get milk from, et cetera– and the alfalfa leafcutter bee, one of these leafcutters, is a really effective pollinator relative to the honeybees at pollinating alfalfa.
We see certain bees that are specialized on squash. So for squash and pumpkin pollination, we see bumblebees and some other of the native squash bees that are really, really effective, relative to honeybees at pollinating squash. So those are a couple of examples. And there are others as well.
IRA FLATOW: Do these wild bees compete with the honey bees?
NEAL WILLIAMS: Yeah. And this is a really interesting question that’s been an ongoing one over the years and in recent years has gotten a lot more attention– again, whether all these honey bees that we are managing are having a competitive or some sort of negative impact on native bees. And it’s a question that’s really difficult to answer. And so I think there are a lot of different positions on it.
What we can say is that when we have honey bees in large densities in an area, there’s pretty good evidence that they are going to have a negative impact on the level of flower resources that are available for other bees in that area. And so it’s a question of numbers, and being very mindful of the way that we’re managing this really abundant social foraging organism in the context of those other bees. But we do see evidence for competition, for sure.
IRA FLATOW: I understand that you published a paper last year about what happens when honey bees are introduced to an area, and the effect on native bees. Tell us about that.
NEAL WILLIAMS: Yeah. So we have a couple of papers that are on this. And I should point out that this work is really work that was led by Maureen Page, who was a grad student at the time. Really, a fantastic piece of work that Maureen led, looking at the impacts of honey bees on the native bees.
And one of the papers that she led, really, we were looking at what the impacts on the pollination of native plants was. So rather than directly at the impact on the bees themselves, looking at what the effect was on the native plants.
And in that case, because the honey bees were numerous and very good at using resources from the flowers, and also because they were not quite as effective, or not as effective at all, on a per-visit basis in terms of pollinating the flowers, they took resources, didn’t do as good a job at pollinating, and so the native bees tended to visit less. And so we saw a decrease in the overall pollination of that native plant.
IRA FLATOW: Now, I know your lab has a special interest in bumble bees. Why is that?
NEAL WILLIAMS: Well, we have an interest in bumblebees. We have an interest in other bees, too. But, yeah, bumblebees, we’ve done quite a bit of work on over the years. And mostly, they have characteristics that allows us to work on them in a range of different questions.
So like the honey bees, in a funny way, we can raise wild queen bumblebees that will make their own little nests– sort of like mini hives– and those hives we can then put at different places in the landscape to explore how the amount of floral resources, maybe the level of pesticides or something like that, will impact the performance of the individual hives. So they’re very amenable.
We also find them to work really well in lab situations. Some bees really do not like to fly in confinement, in cages or in the lab. Bumblebees are pretty good about that.
IRA FLATOW: So your bumblebee is sort of the lab animal, then. It’s not a white mouse. It’s a bumblebee.
NEAL WILLIAMS: Yeah, that’s right. It’s become a pretty useful organism for studying things in the lab. I should say the other group that we work a lot with are mason bees and leafcutter bees. And because of the way they nest, they have been really useful for studying other sorts of questions. So there are a couple of groups that we work well with.
IRA FLATOW: Could you domesticate a bumblebee like we have the honeybee?
NEAL WILLIAMS: Yeah. So people have certainly worked on that question, you can imagine. The really great thing about honeybees, in terms of a pollinator for agricultural systems, is this mobility. You can pick those boxes up and put them in different places. They’re also super generalized. They have large numbers of workers and they’re perennial. So they’re active early and late in the season.
And so bumblebees, although they don’t share all those characteristics, they can be placed into boxes. They can be reared. And so there’s been a lot of work trying to figure out where they’re best usable.
I’d say one of the most interesting places that we use them a lot is in greenhouse pollination. So honey bees really don’t like to be confined to small greenhouse spaces. But bumblebees, again, have this characteristic, where they’re pretty happy to forage.
And so for things like greenhouse-reared peppers or tomatoes that require bee pollination, then bumblebees are a go-to species, and have been really useful. And we increasingly see them in areas where they’re out in field situations, too.
IRA FLATOW: How much do we know about the health of the native bees? Is anyone keeping track?
NEAL WILLIAMS: There are people, for sure, who are increasingly keeping track. There are people who are carefully studying interactions between wild bees and certain kinds of prevalent diseases that we see, and, I’d say, overall broader initiatives that are underway to do monitoring of populations and communities of native bees in different places, both by the government within, say, the national park system on various agency lands, but then also by a lot of citizen groups.
One of the really interesting ones that’s ongoing is work that’s by the Xerces Society. And Xerces has got the Pacific Northwest bumblebee monitoring, and now down into California. And there are similar efforts in the East Coast as well.
IRA FLATOW: Amazing. In recent years, we’ve seen lots of stories about honeybees on the decline, hives collapsing. Are native bees having similar problems or are they not?
NEAL WILLIAMS: Yeah, this is really one of those questions that is a hot area of debate even among bee researchers. So there’s pretty good evidence– I’d say strong evidence, even– that certain species are declining. And we can tell that when we use methods where we look at what we call occupancy.
So we look at places where they have been found in the past and where they’re found now. And that allows us to understand changes both in the distribution– where they’re located across a region– as well as estimate changes in their overall broad abundance.
And so we see, for some groups that we have good data for, there’s evidence of substantial decreases in that metric. For other species, they seem to be doing OK. And so it’s kind of a mixture. And so I think that’s where real caution in trying to draw broad conclusions. But definitely reasons to be concerned among a wide set of different species as well.
So some alarm bells, really, I think, are going off. And so we need to be thinking about this very carefully.
IRA FLATOW: When you talk about alarm bells, what are the threats then to these native bees?
NEAL WILLIAMS: Yeah. So there are a variety of threats that native bees face that are shared with a lot of other organisms, in general, and certainly insects. So some of them will be very familiar to people that are interested in other groups as well.
So bees are threatened by the use of pesticides– insecticides, fungicides, and herbicides– that have negative impacts on bees. They’re threatened by the loss of reliable foraging floral resources. They are threatened by a set of emerging diseases. And this is, again, where the honeybee gets a lot of attention, right? This colony collapse may be resulting from certain viruses, but wild bees, native bees, also have some substantial problems with certain viruses and also other kinds of pathogens.
And then a really big one is climate change. So we have to fully recognize that changes in rainfall and also changes in temperature patterns seem to be stressing bees in different parts of the U.S., for sure.
IRA FLATOW: I’m Ira Flatow, and this is Science Friday, from WNYC Studios.
Can I plant a little patch of wild flowers in a pot or in the yard and really help out?
NEAL WILLIAMS: This is also one of these questions that’s a complex one, but we’ll try not to make it too complex. I mean, in general, planting flowers for bees is a useful thing. The one thing we’d want to be careful about if we were planting flowers in the yard is that we were also being careful about the use of some of these chemical pesticides.
But I think also recognizing the importance of natural areas and broader stewardship of habitat for bees across the landscape is really important. And this tricky one with climate change, too– what are we going to do? We don’t solve climate change with the sorts of things that we would do– small-scale actions– to help bees.
But we can do some things probably– providing shady spots, where they have what we call microclimates that are maybe protecting them from times where there are heat waves that are particularly problematic– things like that that could be useful.
IRA FLATOW: Well, Neal, we could talk about bees all day– which I’m sure is what you do where you live. But have run out of time. I want to thank you for taking time to “bee” with us today.
NEAL WILLIAMS: It’s a pleasure. I really appreciate you giving me the opportunity to talk. So thank you.
IRA FLATOW: Dr. Neal Williams, professor of entomology at the University of California, Davis.
Before we go, we want to say goodbye to two former guests on this show, who were pioneers in their respective fields and who have recently passed away. Ferid Murad won a Nobel Prize in physiology or medicine in 1998 for his work studying nitric oxide’s effects on tissue and blood flow.
Now, at that time, nitric oxide was known simply for being an air pollutant. But as he told me just after his Nobel win, he and his colleagues had discovered its many uses as a therapeutic tool.
FERID MURAD: Nitric oxide is very permeable. It’s very lipid soluble. Therefore, it can almost move anywhere it wants to undisturbed. And it can come back out of the cell if it likes and regulate the biology of a neighboring cell. It may be produced in an endothelial cell lining a blood vessel, but it can also influence the smooth muscle cell adjacent to it, and therefore dilate blood vessels.
IRA FLATOW: And that made it a great way to treat heart disease, respiratory distress, and even erectile dysfunction. Ferid Murad was 86.
Ian Wilmut was an embryologist, who was a member of the team at Scotland’s Roslin Institute that gained fame and startled the world by cloning Dolly, the sheep. Remember, back in 1996? This breakthrough led to a global discussion of the ethics of cloning animals and even people.
Wilmut said many times that cloning human babies was a step too far. As he told me back in 2006, he feared research like his could be frightening at first and then maybe taken for granted over time.
IAN WILMUT: I believe more opportunities still to come from biomedical research than all of the advances that we’ve had so far. And just think how many of those there are. But what we need is basic research to ask as many fundamental questions as we can in order to maximize the number of opportunities that we have available.
And I’m at least as afraid of the fact that people take for granted the opportunities each generation have and do not look forward to the future.
IRA FLATOW: Wilmut’s work extended into stem cell research and an initiative to combat Parkinson’s disease, which eventually took his life this week at the age of 79.