Pollination Overload: Why More Honey Bees Don’t Always Mean Better Crops (Ep. 67)

We’ve long been told that honeybees are the backbone of agriculture; and the more, the better. But what if that’s not the whole story? In this episode, Dr. Ainhoa Magrach joins us to explore how too much of a good thing can backfire. Her research reveals that high densities of managed honeybee hives, often deployed with the best intentions, can actually harm the very ecosystems they’re meant to support. From crowding out wild pollinators to reducing fruit set and biodiversity, the unintended consequences are both surprising and significant.

Drawing from a synthesis of studies, Ainhoa makes the case for a more balanced approach to pollination. She encourages farmers and land managers to look beyond hive numbers and invest in floral diversity and habitat restoration to support wild pollinators. With climate change adding stress to already fragile systems, fostering resilient, diverse pollinator communities is key to sustainable agriculture. 

Dr. Ainhoa Magrach is a Research Professor at the Basque Centre for Climate Change (BC3) and Principal Investigator for the GorBEEa project that explores links between biodiversity, as well as ecosystem functioning and stability by using plant and pollinator communities as model systems. Learn more about the study we discussed here.

Good to know

Dr. Lucas Garibaldi, the researcher Ainhoa mentioned who inspired her study, was a guest on The Bee’s Knees, talking about the importance of wild bees in farming. We’ve also discussed how non-native bees impact native ecosystems.

Transcript

Jacy: [00:00:00] Welcome to the Bees 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.

Today we’re talking about the hidden costs of too many honeybee hives in our landscapes. Ainhoa Magrach led a major review that digs into how the density of managed honeybee hives affects wild pollinators, plant reproduction, and even crop yields. Most studies have looked at whether honeybees are present or not, but this one zooms in on how the number of hives, how densely they’re packed into a landscape can shift the entire ecosystem.

The team behind this review pulled together data from dozens of studies across different crops and regions, [00:01:00] looking at things like fruit set, seed count, and wild pollinator visits. And what they found is eye-opening. Higher hive densities often mean fewer wild pollinators and less biodiversity with surprisingly little benefit to fruit production.

Let’s learn more. We often hear that honeybees bees are essential for farming and food production, but your research suggests that there’s a bit more to the story. What made you want to look deeper into how they might be affecting the environment?

Ainhoa: Well, I guess there were two things that really led me here.

One was that there was a study by Lucas Garabaldi from Argentina where he looked at the productivity of different crops and how both managed and wild pollinators affected this productivity, and they found that it was really a lot of these wild pollinators that were. Increasing the yields of a lot of the crops worldwide, and then you needed to have both the [00:02:00] managed and the wild pollinators to keep this productivity.

A couple years later I was working in a European project and we were analyzing data across different European countries. Looking at different populations of pollinators, and I was in charge of analyzing a lot of this data. And the Spanish dataset was very different because we had a lot of honeybees. And that’s because the areas we were working on, they had all these, uh, managed hives that were close by.

And so we had this huge inflation of honeybees in the area. And so I decided to look more into the detail of data of this increase in honeybees, and we actually found that. Increasingly this honeybee densities in the landscapes, uh, was leading to a decline in the abundance of some other wild pollinator species.

They were competing with them for the resources and increasing this honeybees. It also led to a. Decline in the productivity of seeds of some wild plants. So all of this together really led me to try to understand a little bit more [00:03:00] about what the impact of honeybees are in landscapes because they’re so widely used, um, everywhere, and we really are just starting to, to understand what their impacts are.

Jacy: So let’s talk about those impacts. One of the things that you found was that more honeybee hives don’t necessarily mean better crop yields. Why do you think the assumption that honeybees are the kind of the main and best crop pollinators has stuck around for so long?

Ainhoa: Well, there’s several things, right?

When I tell people that I am a pollinator ecologist, they’re like, oh, I have, I know someone who’s a beekeeper, and that’s the main, uh, thing they tell me, right? Because most of the people associate pollination with just this one species, and a lot of the general population is not aware that actually. When you say bees, there’s actually 20,000 species of bees.

There’s this huge diversity of different sizes, uh, body shapes, et cetera, but they only know about the honeybee, and that’s because it’s a very visible species, very easy to [00:04:00] manage. It’s been used for centuries, not just for pollination, but also for honey production. There’s, uh, for example, in the, in the Basque country where I live, there’s like a social connection with these honeybees.

And for example, in the rural estates, back in the time they used to have, um, the, the hives in the walls of the houses. And so, for example, when someone in the family died. They would go to the hives and they would communicate, you know, the master has died or, or someone has died in the family because they were like part of the, the family.

So there’s also this social connection and they become some kind of a symbol of pollination. But really wild pollinators are way more effective on a per visit basis, and many crops depend on this mix of having both managed and wild pollinators. And the assumption has just stuck because honeybees are convenient and they are familiar, and it kind of overlooks all the invisible work that is being done by other wild pollinators.

Jacy: So another issue you found with too many honeybee [00:05:00] hives was that it can actually reduce the number of wild pollinators visiting the flowers. So what’s going on here? Are honeybees crowding them out or is there something else at play? Well, there’s, uh, multiple

Ainhoa: things that are happening at the same time, so it’s partly competition.

So when you introduce a honeybee hive into a landscape, you suddenly have thousands of managed species, a real large number. They forge very efficiently. They’re able to communicate between each other, the location of the resources, and they can deplete these resources very quickly, and they tend to focus on the most abundant and nutritious resources and these, uh, fewer resources for those wild species that were there.

Also, one of the things that a lot of people are not aware of is that when we think of bees, again, we think of honeybees and we think of the hive, the queen, the workers, but actually a lot of the wild bee species they’re solitary species, so it’s just a female, [00:06:00] uh, laying uh, five to six eggs in the ground and in wood or other nesting structures and trying to feed this five, six babies that she has.

And she’s competing against this really large hives that have hundreds of thousands of individuals. So it’s kind of uneven battle there. Also, it’s not just the crowdiness the sometimes. While planters, they just avoid the flowers that have been visited by honeybees when their numbers are high because there’s also fighting going on.

They fight each other in the flowers and so they directly avoid these flowers. Um, what happens also is that when honeybees. Visit a lot of these flowers, sometimes they deposit too much pollen or they’re visiting the plant too many times, and sometimes they are clogging the styles of the flower. And so this sometimes decreases the reproductive success of plants because they’re putting in too much pollen that the plant cannot deal with.

So it has an impact both for the wild pollinators but also for the [00:07:00] wild plants.

Jacy: So it seems like farmers struggle to figure out a balance when using hives. Why do you think it’s so hard to figure out the right number? And what would you like farmers who are thinking about supporting their crop yields with honeybee hives do differently.

Ainhoa: Well, it’s hard because finding this right number depends on the crop. It depends on the landscape and depends on the season, and it depends also on the wild pollinators that are already present there. So you need to have a lot of information to really have that right number. And there’s no one size.

Fits all formula in this case, right? What happens with other inputs that we have in agricultural settings like the use of, uh, pesticides or herbicides, is that normally those, uh, depend on a company that goes there. Uh, they send an agent of the company to tell the farmer all about their product, when they should use it, how much of it should be used, and we don’t tend to [00:08:00] have this for honeybees, right?

So most people. Try to have an insurance against the losses of their yields, and so sometimes they just say, I’m just gonna stock more honeybees. then I think that I should just, because I don’t wanna have any losses. And that makes sense, right? It’s their livelihood and it makes sense. But what I’d love farmers to do is to consider not just bringing in more hives, but also how to support the wild pollinators that they surely have in their landscape by maintaining floral diversity, semi-natural habitats they have there.

Or. Or hedgerows or other nesting and floral resources that they might have in the landscape because that way they can benefit from a stable and resilient pollinator community, not just from the short term boost of having more honeybees in the landscape that they have with the hives.

Jacy: So your research touches on a bigger idea that even well-intentioned practices can have unintended consequences.

What do you hope people take away from this when it comes to [00:09:00] balancing productivity and nature?

Ainhoa: I guess that the key message is that solutions need to be holistic, that adding honeybee hives can seem like an easy fix and something that’s, uh, easy to do, easy to buy off the shelf, but it undermines wild pollinators in the long run.

And we may be worse off because of this. So I hope that people and farmers and people in agricultural landscapes in particular, see that protecting biodiversity isn’t a luxury. It’s essential for having resilient farming systems, especially in times like now where we are experiencing all these changes in the climate, in land use.

Having these more resilient farming systems and this, uh, more diverse settings is really going to be good. For their productivity as well. So productivity and nature don’t have to be in conflict. They have to find this balance where they can both coexist.

Jacy: So if you could [00:10:00] recommend people do just one thing to support wild bees, what would it be?

Ainhoa: I would say an easy and and straightforward thing to do is plant and protect flowering habitats. Whether you’re a farmer and you leave some space for wildflower strips, or if you live in a city and you’re an urban planner, you can have some green spaces in urban areas as well. Or just, um, yourself in your garden or in your balcony, you can have flowers and offer a diverse, um, set of flowers that are pesticide free throughout the year is one of the simplest and most powerful things that we can all do for wild pollinators.

Jacy: It’s easy to think of honeybees as a universal good, but this research reminds us that more isn’t always better. When hive densities get too high, we start to see real ecological costs, fewer wild pollinators, disrupted, plant pollinator relationships, and ripple effects [00:11:00] across the landscape. What’s powerful about this research is that it doesn’t just raise concerns.

It offers a path forward. By identifying density thresholds and highlighting where the tipping points are, it gives farmers and land managers the tools to make smarter, more sustainable decisions. Thanks to Ainhoa for taking the time to discuss this and to you for taking the time to listen. Lucas Garibaldi.

The researcher Ainhoa mentioned was a previous guest on The Bee’s Knees, and there’s a link to his episode in the article on our website, the Bees Knees website. Until next time, make space for the wild ones.