Whatever happened to the Bee Apocalypse?

[This is a transcript of the video embedded below. Some of the explanations may not make sense without the animations in the video.]

15 years ago, dying bees were all over the news. Scientists called it the “colony collapse disorder”, headlines were warning of honey bees going extinct. Some suspected a virus, some pesticides, parasites, or a fungus. They spoke of a “honeybee apocalypse”, a “beepocalypse”, a “bee murder mystery” and the “head scratching case of the vanishing bees”, which are all names of movies I wouldn’t watch, and in any case the boring truth is that the honey bees are doing fine. It’s the wild bees that are in danger. Whatever happened to the bees and how much of a problem is it? That’s what we’ll talk about today.

The honeybees started dying in 2006. Beekeepers began to report unusually high losses, in some cases as high as 30 to 90 percent of their hives. In most of those cases the symptoms were inconsistent with known causes of honey bee death. The colonies had no shortage of honey or pollen, but the worker bees suddenly largely disappeared. Only a few of the bees were found dead, most of them just never returned to the hive. The queen and her brood remained, but without worker bees, they could not sustain themselves.

Scientists called it the Colony Collapse Disorder and they had many hypotheses for its cause. Some suspected mites, some a new type of virus, some blamed pesticides. Or maybe stress due to mismanagement or habitat changes or poor nutrition. And some suspected… the US government.

In the past years, the number of bees which have been dying from Colony Collapse Disorder has decreased, but we still don’t know what caused it. A 2009 paper that looked at 61 possible explanations concluded that “no single factor was found with enough consistency to suggest one causal agent.”

Quite possibly the issue is that there’s no single reason the bees are dying but rather it’s a combination of many different stressors that amplify each other. It’s parasites and pesticides and disease and a decreasing diversity of plants and loss of habitat. I know this may be controversial to some of you, but not all of your meals should be cheese. It’s not good for you. And it isn’t good for bees either – they should have more than one source of nutrition. Bees also probably shouldn’t eat cheese, so as human we’re a little better off. But much like for us, variety in nutrition is necessary for the bees to stay healthy and if they are faced with large areas of monocultures, diverse nutrition is hard to come by. Doesn’t help if those monocultures are full of pesticides. 

The issue with pesticides alone is far worse than originally recognized because if several of them are used together the effects on the bees can amplify. Just a few months ago, a group of researchers from the US and the UK published a paper in Nature in which they present a meta-analysis of 90 studies in which bees were exposed to combinations of chemicals used in agriculture. They found that if you expose bees to one pesticide that kills 10 percent and another pesticide that kills another 10 percent it’s possible that both together kill as much as 40 percent. The reason for this isn’t that bees are bad at maths, but that effects of chemicals on living creatures don’t add linearly. 

Pesticides and infections still plague honey bees, though they make fewer headlines these days. For example, in 2020 (1 April 2020 – 1 April 2021), beekeepers in the United States lost almost half (45.5%) of their managed honey bee colonies. The major reason that beekeepers reported was a parasitic mite.

However, the numbers may sound more alarming than they really are because honey bees are efficiently bred and managed by humans. Even if they die in large fractions each year, they repopulate quickly and the overall decline of population is small.

In fact, honey bees were brought to most places by humans in the first place. They are a native species to Europe and northern Africa and from there were introduced by salesmen to every other continent except Antarctica. Today there are over 90 million beehives in the world. The typical population of a hive is 20 thousand to 80 thousand. This means that all together there are a few trillion honeybees in the world today.

And while the number of colony losses in the United States is around 40-45 percent each year, which sounds like a lot, the total number of honey bees has been reasonably stable for the past twenty years or so, though it was higher in the 1940s.  Globally the number of honeybees has in fact increased about 45% in the last 50 years. 

The reason that you still read about bee keepers who are sounding the alarm has nothing to do with honey, but that the demand for pollinators in agriculture has increased faster than the supply. The fraction of agriculture that depends on animal pollination has tripled during the last half century whereas the number of honeybees hasn’t even doubled. How big of a problem that is depends strongly on the type of crops a country grows. And it depends on the wild bees.

And that brings us to the actual problem. The honey bee (Apis mellifera) is only one of about 20 thousand different bee species. The non-honey bees are usually referred to as wild bees, and each location has its native species. According to an estimate from researchers at Cornell University in 2006, wild bees contribute to the pollination of 85 percent of crops in agriculture.

While their contribution is in most cases small, with about 20% on the average, in some cases they do most of the work, for example for lemons, grapes, olives, strawberries, pumpkins and peanuts, for which 90 percent of the pollination comes from wild bees. So it’s not that we’d die without them, but according to the Food and Agriculture Organization of the United Nations, losing the wild bees would be a major threat to human food security, and without doubt a serious let down to those who enjoy eating lemon grape olive strawberry pumpkin peanut sandwiches.

Wild bees differ from honey bees in a number of ways. Honeybees live in colonies of several tens of thousands. They are social bees which means they like hanging out together at bee malls and have little bee block parties. No need to look that up, I'm a physicist, you can trust me on these things.

The majority of wild bees, on the contrary, live solitary lifestyles. They get together to mate and then separate again. The female lays her eggs, collects enough food for the larvae, and then leaves her offspring alone, which finally proves that anti-authoritarian parenting does work. If you’re a wild bee.   

Honeybees aren’t the only bees that produce honey, but they are by far the ones who produce most of it. Most wild bees don’t produce honey. But they are important pollinators. Since wild bees have been around for so long they’ve become very specialized at pollinating certain plants. And for those plants replacing them with honey bees is very difficult. For example, squash flowers are open only until the early morning, a time at which many honeybees are still sleeping because they were partying a little too hard at their block party the night before. But a type of wild bees aptly named squash bees (Peponapis and Xenoglossa genera) wake up very early to do that job.

Maybe the biggest difference between honey bees and wild bees is that wild bees receive very little attention because no one sees them dying. They are struggling with the same problems as the honey bees, but don’t have beekeepers who weep over them, and data for their decline have been hard to come by.

But last year the magazine Cell published the results of a study with a global estimate for the situation of wild bees. The authors looked at the numbers of bee species that were collected or observed over time using data publicly available at the Global Biodiversity Information Facility. They found that even though the number of records has been increasing, the number of different species in the records has been sharply decreasing in the past decades.

The decline rates differ between the continents, but the species numbers are dropping steeply everywhere except for Oceania. The researchers say there’s a number of factors in play here, such as the expansion of monocultures, loss of native habitat, pesticides, climate change, and bee trade that also trades around pathogens.

So the problems that wild bees face are similar to those of honey bees, but they have an additional problem which is… honeybees. Honey bees compete with wild bees for food and habitat and they also pass on viruses. Now, a big honey bee colony can deal with viruses by throwing out the infected bees. But this doesn’t work for wild bees because they don’t live in large colonies. And worse, when honey bees and wild bees fight for food they seem to both lose out.

In 2018 researchers from France published a paper in Nature which reported that in areas with high-density beekeeping the success of wild bees to find nectar dropped 50 percent and that of honeybees was reduced by about 40 percent. Something similar had been observed three years before by German researchers.

How bad is the situation for the wild bees? Hard to say. While we have estimates for the number of wild bee species, we don’t know how many wild bees there even are. We contacted almost a dozen experts and the brief summary is that it’s a really difficult question. Most of them just said they didn’t know, and a few said probably about as many as there are honey bees but that’s just an educated guess. So we don’t even know what we are doing to the environment.   

If all this sounds really complicated, that’s indeed the major message. Forget about quantum gravity: ecological systems are way more complex. There’s so many things going on that we never had a chance to properly study in the first place, so we have no idea what’s happening now.

What we do know is that we’ve been changing the ecosystems around us a lot. That has reduced and continues to reduce biodiversity significantly. And the decrease in biodiversity decreases the resilience of the ecosystems, which means that sooner or later parts of them will break down.

It’s really just a matter of time until there’ll be too few bees to pollinate some of the flowers or too few insects to support some of the birds, or too few birds to spread seeds and so on. And we may be able to fix a few of these problems with technology, but not all of them. So, while it is important to talk to your kids about the birds and the bees, it really is important to talk to your kids about the birds and the bees.

We simply don’t know what’s going to happen in response to what we do, and I’m afraid we’re not paying attention which is why I’m standing here recording this video. Because if we don’t pay attention, one day we’ll be surprised to be remembered that in the end we, too, are just part of the ecosystem.

So if you want to help the bees, don’t buy a bee hive. The honeybees are not at risk exactly because you can buy them. What’s at risk are natural resources that we exploit but that we haven’t put a price on. Like clean air, rain, or wild bees. If you have a garden, you can help the wild bees by preserving the variety of native flowers. Quite literally, let a thousand flowers bloom.