Pollinators in Peril: How Habitat Loss, Pesticides, and Climate Change Are Threatening Our Ecosystem (Ep. 51)

Native bees are indispensable to our ecosystems, yet they face numerous threats daily. The rise in pesticide use, habitat destruction, and the looming pressures of climate change have made their survival precarious. Today we’re talking with Dr. Johanne Brunet, delving into how these issues, individually and collectively, impact bee populations.

Dr. Brunet explains that the effects of these stressors on bees go beyond the obvious. For example, pesticides not only have the potential to directly kill bees but can also weaken their immune systems, making them more susceptible to diseases. Similarly, climate change can diminish their food supply by affecting plant production, which is crucial for their nutrition.

The intersection of these problems means that the solutions aren’t straightforward. Habitat loss forces bees to travel further between food sources, using more energy and making it harder to meet their nutritional needs. Meanwhile, pollution and climate change compound these issues, further threatening bee populations.

Dr. Brunet’s lab focuses on interactions between plants and their pollinators. Learn more about the stressors causing the global pollinator decline in the paper we discussed. 

Good to know

Climate change is one of the more complicated challenges facing native bees, as increased temperatures and altered precipitation patterns affect plant growth and the availability of resources for bees. The resulting shifts in plant populations can disrupt entire ecosystems, with cascading effects on both bees and the plants reliant on their pollination.

Transcript

[00:00:00] Welcome to the Bee’s Knees, a podcast wild about native bees. Wild and native bees are under threat worldwide. In each episode, we look at actionable things we can do to support these adorable little guys whose pollination work is crucial for maintaining biodiversity. I’m Jacy Meyer, and I thank you for being here.

Is there something stressing you out? What strategies do you use to cope with the inevitable stressors of everyday life? We talk a lot about the stressors that are behind the decline in global pollinator populations. But is there one threat that impacts native bees more than any other? And how do we alleviate these risks to help bees cope?

Today, we’re taking a deep dive into all the stressors bees face with Dr. Johanne Brunet. How does climate change, habitat loss, pesticide use, And more, impact our bees. So what [00:01:00] are the primary drivers of pollinator decline, and how do they both individually but also collectively impact pollinator populations?

Well, the main driver are habitat loss and change in land configuration, and pesticides, pests and pathogens, pollution, and climate change. So each of them individually have an effect, but they’re really all also interconnected, just to give you an example. If you use pesticide, then either kill the bees, depending if that would be a direct effect, but there’s also a minor, more indirect effect about their behavior, but it can also affect their immune system, so they would become more susceptible to pathogens.

With climate change, you can affect the amount of resource that’s available to the bees because it affects the plant and affects the rewards produced by the [00:02:00] plant. And bees get nutrition through pollen and nectar, and if the pollen is not of the quality they need and the nectar is not in high enough quantity, then it affects also their health.

So it will make also them more susceptible to pests and to pathogens. So all the different themes are connected. So for habitat loss and change in land configuration, we are talking about a loss of resource and less connectivity among habitats, which also means the bees have to travel further in order to go to the next source and that costs energy.

So it is less energy efficient for them. And can create a burden on the bees because they’re small and they need high level of. energy intake. Pesticide, we know if you apply pesticide while the bees are active, you can actually just kill the [00:03:00] bees. But there’s also indirect effect. The pesticide can get into the plant and the pollen, and then the bees will collect the pollen to feed their larvae or feed themselves.

And then that indirectly damages them and affects their health. Pests and pathogens. Well, we know the pathogens. The bees are affected by a number of pathogens, different viruses, um, some bacteria, depending on the bee species. We know more about some bacteria for some bee species than others. And, um, So when they have a weakened immune system, just like human, they will be more affected by viruses that may otherwise not affect them as much.

Uh, pollution we know less about, but we know that, like, for example, heavy metals in the soil can affect the bees. And that the light that we create a lot of light with cities also can distract [00:04:00] and disturb them. But overall, I think we know a bit less about the overall effect of pollution on bees, although it does negatively impact them.

Climate change is a big one because it has different impact on the bees. So it affects them at different level. Climate change will in many times increase temperature, decrease water, depending, uh, the models predict different changes depending on where, what kind of habitats and where it is. But an increase in temperature can directly kill the bees and the larvae.

Both the adults and the larvae, but too high a temperature is detrimental for the bees. And also, climate change will, as I mentioned before, affect the amount of rewards produced by plants. And by doing that, it will affect how much nutrition the bees get, it will affect their health [00:05:00] and it will affect their reproduction.

So it will over time decrease the population size and the size of the hives. So these kind of are the individual effect and I’ve mentioned a little bit how they interact with each other at the beginning. Can you expand a little bit on climate change and the impacts that it has on native bees? Sure.

Well, climate change, we mentioned before, can alter temperature and water availability in different parts of the world. So, higher temperature, for example, can have a very negative impact on larval survival. So the larvae can die if it’s too warm, and so can the adults. So temperature itself can have a direct effect on the bees.

But they will have, climate change will have a lot of indirect effect. We know more and more that climate change impacts the plants. So [00:06:00] the change in temperature and the change in water, especially higher temperature and lower water availability, tends to decrease the size of the flowers, for example, and the plants often produce fewer flowers or more of smaller flowers, but overall they tend to that tends to reduce how much rewards may become available to the bees.

And if that’s the case, as we mentioned, It won’t sustain as many bees if it kills some plants over other. What climate change and these changing climate does too is it affects which plants are healthy. Because if you have low water availability, the drought resistant plant will be favored. And these will tend to reproduce and increase in frequency, while the one that are less water, they need more water, will not do as well.

So you [00:07:00] will change what becomes available to the bees. You may change the overall diversity of plants that are available to the bees. That will modify what kind of amino acid may be present, because some plants. produce more of one amino acid than another plant species. So that may affect the bee health also.

So all these things changing the distribution of plants over time, you may actually, you know, see a big shift if things continue in the plant. And by affecting the bees, if there’s fewer bees, then the plants that don’t need bees will do better. So you will could change the whole ecosystem. And. You know, it’s more than just the bees, but it’s related and it affects the bees and the bees affect the plants and everything could change in ways that I think I’ve mentioned in the article that Our [00:08:00] diet would change because most fruits that we eat depend on bees.

So if you like apples, you definitely need bees to pollinate the apple flowers. And even plants that we eat like, um, Carrots or squash that, you know, well squash you require the flower to be pollinated, but carrots or celeries, you need to maintain those cultivars. So you need to create seeds in order to have the next generation.

And the seed production of all these vegetables do require bees. So, without the bees, it would strongly modify the diet. They would go to mostly grasses, so like, uh, wheat and oat, and they’re all wind pollinated, so they don’t require bees. So, the diet we have, what’s available to us in agriculture would really change, and if you’re like me, I’m a big fan of fruits and vegetables, so I would be very sad.[00:09:00]

I would be very sad, too. So they, it would affect so many things. And then the changing climate too, you know, could affect where you can grow certain crops and who can grow certain crops and self pollinated crop may not be as wildly available in some parts of the world. So it would have a, you know, given we all need food in order to survive, it would have major consequences on human and what they call food security.

Another aspect that your paper mentioned was the negative impact of managed bees on wild bee species, right? So, what strategies would you recommend to strike a balance between agricultural demands, But with, uh, going along with the conservation of wild bee populations. Well, one thing I think that would be important is one of the problem with managed bees that we’re [00:10:00] finding more is that they do carry more diseases.

It’s kind of a humans living in aggregation when bees are close together and hives are close together. It’s easier to transmit diseases from hive to hive. So if we could try to better understand this and control the disease in the managed bees, then it would limit the spillover, we call, of disease from managed bees to wild bees.

So that would be one thing we could do to try to help wild bees. Another thing is definitely in agriculture, if we use pesticide, we should always spray in the evening. And for years, there’s been methods for trying to control pests with minimizing chemical use. And now this is also happening for pollinators.

So they call it integrated pollinator management strategies. And one of them, [00:11:00] and a major one, is to spray. During the evening, because bees are never active during the evening. Another thing we should do is to make sure the bees have enough food. One of the big problem with agriculture, especially when you have huge fields, is they have a lot of one type of food for a period of time, and then they don’t have much around.

So, to make sure that the fields Are surrounded by natural habitats that provide flowers and food for bees to make sure that maybe if you grow crops, you grow crop throughout the year with different type of crops that can feed the bees throughout the year, we bring a lot of honeybees to a field in agriculture, not because they’re the best pollinator on the per visit basis, but because they have such huge colonies.

By sheer numbers, they are able to pollinate a [00:12:00] field. So, but understanding that, that other wild bees are often, per visit, much better pollinators. And understanding that wild bees play a big role in agriculture. And I know as an example, in the United States, now alfalfa fields are huge. But Pre 1950s, the fields were much smaller and they mostly rely on bumblebees and natural bumblebees to pollinate the fields, but now it’s impossible with the size of the field.

So making sure, like sometimes also agricultural scheme are used, like flower strips to try to help provide food for bees in agriculture. So they have different variety of food because diversity is important because different plant species provide different amino acids in through their pollen, and it’s needed for the bees to remain healthy.

So [00:13:00] all these things could be done, I think, to, you know, have more sustainable agriculture and understand that the native bees play a big role in agriculture. You know, sometimes it’s us because of the way we actually plant that makes them less important, but it’s been shown when fields are smaller, they actually play a fairly big role and they can help increase the crop.

Even sometimes self pollinated plants, crops, benefit from presence of native bees. Because they still outcross, I think, when the bees are present some, so, you know, balance and trying to not just think about honeybees, but think about bees as a whole. Not just think about agriculture, but things as a managed system of both agriculture and wild [00:14:00] population is very important, I think, for us to really, you Maintain the bees and maintain, you know, a system that we can keep for years to come.

So all the drivers of pollinator decline that you’ve identified, which do you think is the most critical to address immediately? And how will we address it? Well, I hate to say, but I think that they all very important to address immediately. I don’t think one should be prioritized. I think the pesticides we are Using and starting, you know, people are, farmers are applying more at night, so they are doing that and they should keep doing this.

Habitat loss is something that affects not just bees, but a lot of other, you know, even the plants that are where we limit their habitat. [00:15:00] Climate change is a hard one because it’s a complicated one to control. So it’s much easier to spray at night than it is to try to reduce climate change. But yet, it has a major impact on bees, and it has a major impact on crops, so it’s not just the bees that will be affected, but the reproduction of the crops are also at stake, and so many things are involved in the climate change, so personally, I feel like we should attack them all up front.

And they’re all things that will help not just the bees, but humans too, because we depend on bees enormously for our food production, but we also depend on plants and because we would like to eat the food that the bees are pollinating. And, um, you know, so it is quite important, I think, to attack, in my opinion, all of them up front.

So if you [00:16:00] could encourage people to do just one thing to help support native bees, what would it be? It would be to plant gardens. I know a lot of people do not like dirt, and they do not like to play into the dirt, but dirt is very important. Plants are very important. There’s nothing more fascinating in many ways for a child or a human to plant a seed and see a plant grow.

Out of it. And to watch the plant grow. So I think if you think about planting a garden like it, I love raspberries. So I planted raspberries and the variety I plant flowers late until September. So all the bumblebees come to my raspberry. In September, and it’s a mutual benefit because I get beautiful raspberries and the bees get their food so everybody’s happy.

So if you think about it this way about planting a [00:17:00] garden, you can offer plants throughout the year to the bees and different type of bees and you will get something in return. So, I really encourage people to try to plant. If you just want to plant a garden without, you know, just flowers, it would be good.

But then think about the type of flowers because some flowers don’t attract bees that much. The other thing, if you plant a garden, leave bare ground so that the bees can nest. A lot of bees nest on the ground and you can put also twigs. of different sizes, hollow stems that will attract other type of bees.

So, and it’s not hard. So if we all did this, we would help in some ways provide food to the bees. Pollinator decline seriously impacts biodiversity conservation, reduces crop yield, and threatens food security. As Johanne said, we need to understand how each threat impacts bees, [00:18:00] both individually and collectively, in order to create strategies to protect them.

And what’s the actionable advice from Johanne to alleviate one stressor? Grow vegetables for mutual bee and human love. Thanks for listening, and until next time, get dirty.