The Secret Life Of Tiny Bees

10:49 minutes

sweat bee
A sweat bee. Credit: John Flannery

Bumblebees and honeybees are important pollinators that everyone has spotted buzzing out in fields, moving from flower to flower. But you may have missed the smaller bees—some the size of a grain of rice—that also play a big role in pollination.

In a study in journal the  of the Proceedings National Academy of Sciences, researchers found that these bees measuring a millimeter in size could move pollen distances up to a million times their body size.

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Biologist Shalene Jha, an author on that study, discusses how these small bees play a role in pollination and genetic diversity for plants and trees. She also introduces tiny bees like the sweat bee, which drinks the sweat and tears of animals.

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Segment Guests

Shalene Jha

Shalene Jha is an associate professor of integrative biology at the University of Texas at Austin. She’s based in Austin, Texas.

Segment Transcript

IRA FLATOW: You’ve probably sat out in a field somewhere, and a buzzing bumblebee or a honeybee might catch your eye. You watch it carefully, it hovers and inspects each flower. And then it takes off mid-flight onto the next flower. You know, these are fascinating things to watch.

But what you may not have noticed are the smaller cousins of these bees. Some are no bigger than a grain of rice. And they’re just as fascinating as their charismatic cousins, like the bee that drinks the sweat and tears of animals. Did you know about that one? And then other there’s the carpenter bee, the smaller carpenter bee, the hairy belly bee.

The list goes on. There are thousands of these tiny bees. And they also play a big role in pollination. My next guest studies how that works. She’s an author on a study out this week in the proceedings of the National Academy of Sciences. She’s going to take us into the world of these tiny bees.

Shalene Jha is an associate professor of integrative biology at the University of Texas in Austin. Texas Day on Science Friday. Welcome. Welcome to Science Friday.

SHALENE JHA: Thanks, Ira.

IRA FLATOW: When you think of bees, you know, you imagine a colony of bees. But I understand that most of these smaller wild bees, they’re loners?

SHALENE JHA: That’s right. About 90% of all bees are actually solitary. So despite kind of the public impression that all bees are like honeybees and bumblebees, we have a lot of these bees that are living on their own.

IRA FLATOW: So where do they live?

SHALENE JHA: So most bees live underground. So they nest under the soil. We also have a lot of bees that nest in stems of trees or in rotting logs. So there’s a lot of diversity in where these bees live, and also the kind of social versus solitary lifestyle they maintain.

IRA FLATOW: Tell me about something called bee bread.

SHALENE JHA: So bee bread is this mixture of honey and pollen and some other secretions that solitary bees create for their offspring, for their babies. And they create this little ball of resources, and then they’ll lay their eggs on top of this ball of food.

And the exciting thing about this is that there’s a lot of specious interactions going on. There’s actually fungus and bacteria in that bread that adds to the nutritive value of that bread. And so they lay their eggs, and then that egg will hatch into a larvae. And as it grows, it’ll consume that food. And so bees provide this care for their offspring in the form of this bread.

IRA FLATOW: Our number, 844-724-8255 if you’d like to talk about bees. This is fascinating, because I’m sure most of us don’t even know that these bees are out there. Let’s talk about some of the more fascinating ones.

The sweat bee. Does it really drink our tears? Do we know it’s happening?

SHALENE JHA: It does, actually. So it got its nickname because humans noticed it drinking their own perspiration, and also the fluids of other animals. There are some great photos in National Geographic showing butterflies and bees drinking the tears of alligators and turtles. And what we believe is going on is they’re trying to get a limited resource. So things like sodium and other micronutrients can be limiting for these bees, and so they need to get them somewhere. And tears or sweat are often good places.

IRA FLATOW: You know, I’ve seen the big carpenter bees around the house. They’re always drilling holes. I can stick my fingers in in my mailbox post. What’s the difference between these big ones and the tiny carpenter bees?

SHALENE JHA: Yeah, so great question. So these bigger carpenter bees are nesting in large chunks of wood. And they– both the big ones and these little tiny carpenter bees, called the ceratina bees, they tend to nest in little stems of trees. But they’re both really fascinating, and they’re actually pretty closely related.

And they often go back to their old nest sites and kind of refurbish the homes where they were born, so where their mothers actually laid them. And so they have this high level of– we believe– high level of fidelity to these woody materials in which they were born.

IRA FLATOW: And I know you recently published a study that you did in Panama that looked at the role these rice-sized bees play in pollination. Tell us what you found.

SHALENE JHA: Yeah. So in the study, we were investigating basically how these trees were engaging in sexual reproduction. And the way we did this was through a paternity analysis. And it’s very similar to the way humans conduct paternity analysis. So you look at the DNA of an offspring, or a child, to figure out who the parents are.

And we did the same thing with plants, where we looked at the DNA in a seed to figure out where pollen was coming from. And what this allowed us to do was create kind of a little roadmap of where pollinators had been traveling before they landed on a receptive flower. And this was important for us to understand because, although most global crop species depend on animal pollination and most flowering plants in general depend on pollination, we actually knew very little about how they move.

So what we found were these tiny bees were traveling more than a mile. And it’s basically a million times their body size in terms of distance. So you know, to put it in human context, it would be like traveling from Chicago to LA based on just the energy that you produced.

IRA FLATOW: Wow. Our number, 844-724-8255. Talking about bees on Science Friday from PRI, Public Radio International. Let me go to the phones, because people love to talk about bees. And let’s go to Max in La Crosse, Wisconsin. Hi, Max.

MAX: Hey, Ira.

IRA FLATOW: Hey there.

MAX: This is Max. Right now, I go to UW La Crosse. I’m a microbio major. And I’m trying to isolate yeast from the guts of bees. And I was just curious how the gut microbiomes vary between these solitary wheat bees and the bees that are commonly found in colonies.

IRA FLATOW: Our favorite topic.

SHALENE JHA: Yeah, that is a fantastic question. So work on the microbiomes of bees is actually something else that we do here at the University of Texas in Austin in Nancy Moran’s lab. And what we’re seeing is that there is quite a lot of variation in microbiomes. And it depends very much on environmental drivers, histories of these bees, but very likely social interactions. Because we know that colonies can engage in trophallaxis, so this exchange of fluids through their mouth parts, can actually alter these microbiomes. But that’s still a research direction that we’re moving in. And I think it’s a really interesting and hot topic.

IRA FLATOW: If these tiny bees don’t live in hives, I know over the winter, the regular honeybee hives, they generate, like, over 90-degree temperature inside while it’s freezing outside. How do these solitary bees stay alive?

SHALENE JHA: That’s a great question. So most solitary bees actually live for pretty short time periods, so just a few weeks at a time. So they’re out foraging for food for their offspring, that next generation. And they carry out that work in oftentimes these very short periods where, you know, their floral resources or their flowers of interest are blooming.

And so most of them don’t survive the winter. They actually just live for that short summer, spring, late fall period, and then lay their eggs, and then the next generation emerges the following year.

IRA FLATOW: Let me go to Linda in Sacramento. A quick question, Linda. Hi, there. Linda, are you there?

LINDA: Can you hear me?

IRA FLATOW: Yes, go ahead.

LINDA: Yes, I’m here. I’m just wondering if some of these bees that you’re talking about, some of the solitary bees that nest underground, if they’re subject to insect problems like the honeybees have. For example, varroa mite?

IRA FLATOW: Hm. Good question, yeah.

SHALENE JHA: Absolutely. And you know, there’s a lot of interesting research into parasites and pathogens, including varroa mites, including diseases like nosema and crithidia parasites. So there’s lots of sort of potential threats to these wild solitary bees. The reality is we just know less about them because we’ve spent a bit more of our energy on honeybees and bumblebees. And so this is a new area of research which we’re starting to investigate.

IRA FLATOW: Can we see– I know you do your studying down in the tropics. Can we see these tiny bees everywhere? Up here, northern latitudes?

SHALENE JHA: Absolutely. So, all over. So some of these small bees that we talked about a little earlier like sweat bees exist all over the world in terrestrial landscapes, so in plant communities where they provide pollination services. And in the tropics, we tend to have a lot of these what we call stingless bees. These are bees that are closely related to honeybees, but they’re much smaller in size.


SHALENE JHA: And are really important for native plant reproduction, as well.

IRA FLATOW: Well, Dr. Jha, thank you very much for taking the time to be with us today. It was fascinating.

SHALENE JHA: Thanks so much for having me, Ira.

IRA FLATOW: You’re welcome. Shalene Jha is associate professor of integrative biology at the University of Texas in Austin. That’s about the– oh, run out of time. But before we go, one last thing.

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