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Honeybees and Monoculture: Nothing to Dance About

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Beehives stacked and secured on a truck for transportation (Photo: Mark Lehigh)

Beehives stacked and secured on a truck for transportation (Photo: Mark Lehigh)

With all the talk of honey bee decline in the news, you may already know that honey bees don’t just make honey. They also give us almonds, cherries, avocados, raspberries, apples…pretty much everything delicious. Of course, there are plenty of native pollinators that can also do that job. But domestic honey bees (first brought to the American continent in the 1600s) are great for large-scale agriculture for a couple of reasons. First, they live in huge colonies of tens of thousands of bees: one colony can visit 50,000 blossoms in a single day. Second, those colonies can easily be picked up and moved around to wherever they’re most needed. So the same bees that are used in February to pollinate almonds in California can be moved in April to pollinate cherries and apples in Washington state. Over a million honey bee colonies are moved around the US, going from crop to crop as they come into bloom.

The honey bees in a single colony can actually move among crops in a similar way, but on a much smaller scale. When a bee comes back to the hive with a full load of sweet nectar or nutritious pollen (food for bees), she’ll do what’s known as a “waggle dance”—pointing other bees in the direction of the flowers she found.

It’s been more than 50 years since Karl von Frisch first figured out what bees were saying with the waggle dance, but we still don’t know much about why. What does the colony as a whole gain from dancing—can they collect more food faster, or with less effort? When is the ability to dance most useful? To figure this out, I decided to mess with the bees a bit, and make it so that when they danced, it came out gibberish. Then I asked how this affected how much food the whole colony could collect. What I found was that dancing was much more important for large colonies than it was for small ones [1]. This is because a large colony can send out hundreds or even thousands of bees to search the landscape in parallel, getting lots of information very quickly. If any one of those searchers finds a lush patch of flowers, she can do a dance back at the nest and recruit plenty of other bees to help her collect pollen and nectar from those flowers. I also found that dancing was most important when a wide variety of flowers were in bloom [2]. So, particularly when there is a nice mix of different types of flowers available, the bees in one big colony can actually move themselves around among different flower patches as they come into bloom.

Almond flowers as far as the eye can see (Photo: David Gallagher)

Almond flowers as far as the eye can see (Photo: David Gallagher)

But the way agriculture is done these days, there doesn’t seem much point to dancing. Why bother telling your hivemates about a great patch of almond flowers, when there are only almond flowers as far as the eye can see? By planting crops in monoculture, we’ve increased the scale of flower patches so much that a honey bee colony can’t effectively search across many patches: they’re stuck in just one. That patch blooms for a short period of time, and then the bees have nothing else to eat. So instead of letting the honey bees move themselves around on a scale of several miles, we’re forced to truck ailing colonies across states. This is terrible for the bees: too much stress and poor nutrition make them more vulnerable to pesticides and diseases. As a result, we’re losing around 30% of our bee colonies each year, and we may soon be at the point where there aren’t enough bees to go around.

How can we fix this problem? A recent report released by the USDA and the EPA suggests we need to approach it from a number of angles, including better control of diseases and parasites and more research on the effects of potentially harmful pesticides. And—I think, crucially—we need to figure out how to quit moving so many bee colonies over such long distances. Instead, we should let the bees make the most of their amazing capacity to search the landscape and go where the flowers are. That means making a broader diversity of flowers available to bees on a scale where they can really take advantage of them. We’ve got to convince farmers to plant a wider variety of crops and let weeds grow on crop margins, and persuade landowners to maintain wild habitat near agricultural land. That’s going to be hard. But if it means that beekeepers can maintain big, healthy colonies of honey bees—and that farmers can attract native bees to pollinate their crops as well—wouldn’t it be worth it?

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For more information on honey bees and native pollinators, and how you can get involved, see:

Pollinator Partnership – promoting pollinator health through public involvement and education, e.g. through National Pollinator Week and regional planting guides

The Xerces Society – conservation of native pollinators; see the Bring Back the Pollinators campaign and their book Attracting Native Pollinators

Project Apis m. – enhancing honey bee health; work directly with farmers and beekeepers, and support scientific research

References:

[1] Matina C. Donaldson-Matasci, Gloria DeGrandi-Hoffman, Anna Dornhaus, Bigger is better: honeybee colonies as distributed information-gathering systems

Animal Behaviour, Volume 85, Issue 3, March 2013, Pages 585-592

[2] Matina C. Donaldson-Matasci and Anna Dornhaus, How habitat affects the benefits of communication in collectively foraging honey bees

Behavioral Ecology & Sociobiology, Volume 66, Issue 4, April 2012, Pages 583-592.

The views expressed are those of the author and are not necessarily those of Scientific American.

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