Sleepyheads: The Effects of Insecticides on Bee Sleep (Ep. 20)

How do you feel after a poor night’s sleep? Sluggish? Not really motivated to work? Today, we’re talking about a study that looked closely at the effects of pesticides on bumblebee behavior. Our guest, Kiah Tasman, gave bumblebees nectar sugar infused with neonicotinoids, a commonly used pesticide. She then observed the bees in a foraging arena, and the results were alarming. The pesticide appeared to disrupt the bumblebees’ body clocks, causing them to forage less and primarily at night. They also slept more during the daytime, leading to a significant disruption in their normal patterns of behavior. 

Read Kiah’s complete study here and learn more about her work here. In case you missed it, Episode 19 also discusses pesticide use and bees. Dr. Clara Stuilgross and I discussed her study, which looks at the carryover effects of pesticide exposure. 

Good to know

In our discussion, Kiah mentioned how she used radio frequency identification tracking to monitor the habits of individual bees exposed to neonicotinoids. You can read more about how that was done in this article.

Transcript

[00:00:00] Bumblebees are vital pollinators for crops and wildflowers. In Europe, three of the five most important crop pollinators are bumblebees. Without them, many crops would suffer, and crop pollination in Europe, which is worth over 22 billion euros per year, would be significantly impacted. However, despite their ecological and economic value, bumblebees are facing significant population losses.

In Europe, 46 percent of bumblebee species are experiencing decline, and 24 percent are at risk of extinction. This is a concerning trend, as bumblebees play an important role in maintaining food security. In our previous episode, we talked about the carryover effect pesticides can have in bees. [00:01:00] Even one instance of exposure can affect them and their offspring for years to come.
Today, we’re looking more closely at one specific insecticide and the notable effects exposure has on bumblebees. Kiah Tasman, lecturer at the University of Bristol, found that bees sleeping and foraging habits are severely impacted by exposure to the insecticide neonicotinoid. Kiah is joining us to explain more.

Kiah, great to have you. Can you tell me a bit more about neonicotinoids and, given their harmful effects to pollinators, why are they still in use? Neonicotinoids are a group of pesticides that were developed in the 1990s. They’re based on nicotine, so nicotine or tobacco plants have been used as a pesticide for hundreds and hundreds of years.

And this is the kind of newer version using the same mechanism. And they’re used because they’re systemic, which means that when they’re sprayed onto the plants or onto the [00:02:00] seeds, they grow into all of the tissues of the plant, so they’ll grow into the stem and the leaves and things, and so that makes them very efficient pesticides.

But it also means they grow into the flowers. So they’re present in all of the nectar and the pollen of the plants as well. And so that means they’re very harmful to pollinators. And they’re still used, I guess, because they are very efficient pesticides. And also because they act on a set of receptors that are found throughout the kind of central nervous system in the brain in insects.

But aren’t really found in the central nervous system of mammals. So they’re seen as fairly safe compared to kind of older pesticides. So your study found some particularly concerning effects of this insecticide on bumblebees, including sleep disruptions and how they forage. How do these impact the bees daily lives? Yeah, so I found that, as I said, there’s these kind of receptors in, in insect brains that these pesticides work on.[00:03:00]

And these receptors are also found in the part of the brain that kind of manages the daily rhythms of the insect. So bumblebees, like us, are diurnal, so they’re most active during the day. They go out and forage during the day. Obviously, this is when flowers are kind of open and the pollen and nectar is available. So that’s when they’re active, and then at nighttime they sleep, like we do.
But it seems like these pesticides were kind of activating this bit of the brain, which kind of sets the rhythm, and is usually just activated by daylight. And so it was making them kind of active at different times. So they were going out and trying to forage at night time, they were sleeping during the day, and it was kind of messing up all these different rhythms so they were kind of less active than normal, but also active at the wrong times of day, and sleeping at the wrong times of day.
And so they were kind of foraging less, foraging when flowers weren’t available, they weren’t kind of bringing back as much forage. So yeah, it was impacting their kind of ability [00:04:00] to do what they need to do for the colony to grow and survive. And how did you conduct the study? So I looked at the whole kind of colony level.

So we had a bunch of different colonies in the lab in a kind of controlled environment attached to foraging arenas. And then in the foraging arenas, they had access to sugar water with different kind of concentrations of these neonicotinoids. And then the foragers had little radio frequency ID tags attached to them.

So these all different, have a different identification on them. And that can be scanned as they come in and come out of the colony. So we were able to monitor them and we knew who was coming out of the colony and who was going in and what time they were doing that and how long they were out foraging for.
So that gave us a nice measure of kind of each forager’s, activity levels, when they were going out at different times of day, and how long they were spending foraging as well. And then I also looked at them on an individual [00:05:00] level, because obviously you can’t see into the colonies, so you can’t see as much detail.

So I also isolated a bunch of foragers and put them into little glass tubes. And then we looked at them with different concentrations of neonicotinoids, looked at how often they were kind of walking around and active, what time of day they were active, when they were sleeping. So this kind of gave us a more in depth look as well at their individual activity levels.

So with the bumblebees foraging habits being impacted by the neonicotinoids, what impact does that end up having not only on their lives and the colony, but their ability to pollinate? So at the colony level, it has a really big impact because obviously foraging for pollen and foraging for nectar is really important for the colony to grow.

And if the colony doesn’t grow, then it struggles to reproduce. So all of the workers in the colony kind of growing the colony so they can produce the sexuals, so the males and the queens. But [00:06:00] only the biggest colonies will produce queens. So if colonies are struggling to grow, then they can’t produce queens. And there was one really good research paper that found that kind of pesticide exposure, neonicotinoid exposure, reduces queen production by 85 percent in bumblebee colonies.

And so they’re not producing the queens that kind of will start and form the next bunch of colonies. And so it really impacts bumblebee survival and reproduction. So that’s a big factor. And then bumblebees are kind of huge source of pollinators. So insect pollination, I think in Europe, at least is important for around 80 percent of wildflowers and 75 percent of crops.

So it’s really, really important. And bumblebees do a lot of this, so they’ve got quite specialized long tongues, so there’s a lot of crops, things like tomatoes and a lot of kind of stone fruits that honeybees struggle to pollinate, and so they’re really dependent on bumblebees, and so it’s really important for our food security that we [00:07:00] kind of protect these species and make sure that they’re able to pollinate the food that we eat, but also to kind of protect biodiversity of other wild plants as well. You identified two pretty big problems this insecticide causes in bees, plus the stat you just mentioned about the inability of a colony to produce a queen.

What other problems do these insecticides cause? So, because they activate these receptors that are found all the way through the central nervous system, they have a huge amount of impacts. So they can impact things like learning and memory, so they reduce learning, which makes it harder for bees to remember where there’s good patches of flowers, and to kind of navigate to these.
They impact things like reproduction, so not only on the colony level, but on the individual level. So it reduces sperm count in males, and also kind of egg production by queens. And it really interferes with their kind of behaviour with each other as well, so things like grooming behaviours and stuff are reduced as well by these pesticides.[00:08:00]

So, a huge amount of different things. Where would you like to see the research go in this area? I’d like to see it kind of look at, so things like soil exposure. So obviously bumblebee queens, the whole of the winter they spend kind of hibernating underground. And there’s also a lot of wild bee species that will build their nests underground as well, things like mining bees.

And one of the problems with these pesticides, with the neonicotinoids, is that they can wash off into the soil and into the water, and then they have a really long half life. So they can keep building up in the soil and the water, and, uh, kind of growing into other wild plants and stuff, but also just staying there in that soil.

And so it’s quite possible that when these… queens are hibernating, they’re kind of experiencing quite high levels of neonicotinoids just from soil exposure as well, and the same for kind of nesting bees. And so I think this is possibly a big route of exposure that’s not had as [00:09:00] much research, and it’d be great to look into that.

Do you see insecticides like these being banned, or at least severely restricted, anytime soon? Well, what’s great is that in the EU they have been banned. Or at least the kind of major neonicotinoids have been banned, which is brilliant. Unfortunately, that’s not happened kind of elsewhere in the world, and I’m not sure how likely that is to happen.

And we’re also seeing some rowing back of this ban as well. So in the UK, we keep having kind of special measures granted, which allow neonicotinoid use for specific crops or in specific areas. And those are becoming very common, which is a problem. So we’ll see. But it’s also… an issue that there’s not a huge amount of research into kind of safe alternatives.

So when we ban these neonicotinoids, we just end up using the kind of older, equally unsafe pesticides, things like organophosphates. So we really need to be looking into kind of safe alternatives [00:10:00] or different ways of farming that reduce the need for these pesticides. Do you have a favorite bee? I really like the long horned bee.

So this is found in kind of southwest of England. They’re very sweet, very small and fluffy. And the males have really long antennae, which they use to stroke the antennae of the females when they’re mating. So they’re very sweet. That is the sweetest bee I’ve ever heard of. What in your opinion is something that we all can kind of do to support bees?

So definitely things like… planting kind of bee friendly plants in our gardens. So yeah, as we found earlier on, kind of, bees are quite dependent on gardens, especially in maybe kind of late July, August, when there’s not many crop flowers around and wildflowers aren’t kind of flowering anymore. So kind of bee friendly plants during that time of year is great.

Also things like bee hotels. And also just [00:11:00] contacting local politicians to try and reduce, kind of, the use of pesticides. If you’re in the UK, trying to get them to stop giving these special uses for pest, for neonicotinoids.

And also trying to get them, like, councils and stuff to plant wild plants in verges or roundabouts or any bits of land that aren’t currently being used. What bees suffer from insecticide exposure is something we can all relate to. Lack of sleep, trouble focusing, struggles at work. Sadly, while we can usually fix many of these issues for ourselves, bees are being affected through the very food that they eat.

And, as Kaih mentioned, perhaps in the ground they nest in. If you live somewhere where neonicotinoids are legal, please consider contacting your local government or environmental charity to see if there’s any legislation in the works to have these invasive insecticides banned. Thank you so much for listening, and don’t forget to review and [00:12:00] follow the show, and of course, tell a friend.

More information, as always, is available on the website, thebeesknees. website. See you in two weeks, and until then, keep buzzing.