Plastic Bees


There has been a flurry of excitement in the media over a recently-published observational study describing the “behavioural flexibility and adaptation” of solitary bees to our “plastic-rich environments”. In a nutshell, during the course of a larger field study looking at wild bees in urban landscapes, researchers in Toronto discovered that some urban Megachile bee species in the city had lined their nest cells with plastic materials.

Megachilid ‘leafcutter’ bees are solitary bee species that build their nests as rows of sealed cells inside natural cavities, like wood hollows or plant stems. To protect the developing larvae inside, the cells are lined with natural materials, like bits of leaves, flower petals, or plant resins.

A cross-section of an alfalfa leafcutter bee nest, showing the individual nest cells. (Source: New Brunswick Department of Agriculture, Aquaculture & Fisheries)

A cross-section of an alfalfa leafcutter bee nest, showing the individual nest cells. (Source: New Brunswick Department of Agriculture, Aquaculture & Fisheries)

Leafcutter bee nest (Source: Queensland Museum)

Leafcutter bee nest (Source: Queensland Museum)

So what do these bees do when they live in a city where the natural world is in short supply? Use the most available alternative material…ubiquitous plastics. The researchers found that one species (Megachile rotundata, the alfalfa leafcutter bee), which normally uses snippets of plant leaves to line their nests, had incorporated tiny pieces of plastic shopping bag into nest cells. The other species (Megachile campanulae), which normally collects resins from plants or trees to build the nest cell, had made do with a type of polyurethane-based sealant usually used to seal window frames.

Media coverage has been extensive, from science media to tabloid dailies, but the general theme appears to be the same: no need to feel bad about our impacts on the environment, animals are learning to cope just fine. Is this a “a rare piece of good news for bees“? Could it be optimistic evidence that bees are learning to adapt to a world increasingly dominated by humans, giving hope to the future of global food security?

Most newsy versions of the story focused on the study’s apparently remarkable finding that all the bee larvae in plastic-lined nests survived and were parasite-free. Apparently Plastic was no longer consorting with the Grim Reaper and had regained its crown as the patron of modern society…here was an ethical paracetamol for our collective headache of trying to live lightly in a consumerist world!

It’s true, plastic can prevent parasites from getting to bee larvae, as this USDA factsheet from 1970 discusses – nest cells constructed in plastic drinking straws will produce parasite-free bees, because the parasite cannot get through the plastic straw wall…but as we all know, plastic doesn’t breathe, and up to 90% of the larval brood can be lost to mould infestation in solid plastic nests, parasites or no parasites.

There is a bit more to the Toronto study that the newsy versions didn’t mention. Firstly, the urban bee nests did not have hermetically-sealed plastic linings – they were made up of mixed pieces of plastic and leaves. Therefore, their survival cannot be compared to survival inside solid plastic walls. Secondly, some of the bees emerging from the sealant-lined cells were parasitised by a generalist brood parasite, Monodontomerus obscurus. Thirdly, although the information in this observational study is important and useful, the sample size was too tiny to be considered evidence of any real effect.

The authors were simply reporting an ecological observation that occurred as part of a larger replicated study looking at other factors. In total, the number of trap nest cavities set out around Toronto for bees to settle into was 5700 (190 sets of 30 cardboard tubes). Out of 5700 possible nest cavities, this observational article is talking about 2 cavities, in which 5 individual brood cells were found to be plastic-lined. This is definitely not proof that wild bees can survive in plastic nest cells!

In their discussion, the researchers note the potential for plastic linings to stop parasites, but they also remind us that there are “many other examples of plastics inhibiting essential functions including mobility, foraging, and respiration in other animals”. Sadly, the newsy versions will be read more than the original article, and very few of these versions (briefly) acknowledge the other side of the story (e.g. here and here).

It is comforting to think that wildlife can adapt to changing environments, especially when we are responsible for that change. But we are already aware of the negative effects plastic exposure can have on foetal development, hormone functionskin health and even the results of scientific laboratory studies. Sometimes the effects aren’t seen immediately. What will we see in a few years, after multiple generations of bees have built and emerged from plastic-lined nests?  Is this a cause for celebration that wildlife can survive human domination, or more incentive to start cutting the plastic umbilical cord?

© Manu Saunders 2014

13 thoughts on “Plastic Bees

    • “only interested in a story”…I agree, especially sensational or dramatic ones! The line between ‘tabloid’ and ‘broadsheet’ news has certainly become increasingly blurred in the last couple of decades…

  1. It is actually nothing knew that journalists engage in heavy cherry-picking when they report scientific findings. Which does not make it less sad, of course. In this case, the striking point is that the hurrah-reactions on this study are absurd even without knowing that crucial aspects have been ignored by newspapers. Even if plastics would do any good to this one species of bees, I do not see any reason to be optimistic that you could generalize this in any way and say “hey, plastics are OK for nature!”. That’s just silly. Knowing in addition that the study has been misrepresented makes these optimistic self-assertions even more ludicrous.

    • You’re right, it is not new for some journalists to cherry-pick when writing science stories. But I think this practice is having a lot more impact on public attitudes to scientific and environmental issues today than it might have previously, because more and more people are using popular media as their main, or even only, source of information and education. It is easy for trained scientists to find the holes in the Media’s version of a scientific study, but often the non-scientific public won’t be able to access the original study, or won’t have the skills to critically assess the study even if they did get to read it – so how will they ever know that the media has misrepresented it? I also agree with you that the “hurrah reactions” on this particular study are a bit desperate – especially the “good news for bees” article that I linked to above!

      • I am not sure whether the situation has really worsened in recent time. Earlier, people just didn’t care about science (partly because media didn’t). Now they get a piece of information now and then, but in the vast flood of news every day, I think they rarely notice science-related stories. So, in the end, the broad public didn’t care earlier and still doesn’t. It may well be that we overestimate the impact of those newspaper stories because we care about their message. Most other people don’t. Why should they?

        • You could be right, I haven’t been around long enough to truly claim that things are better or worse than yesteryear! :) Although I don’t think it helps for us scientists to believe that most other people don’t care about what we do – it just encourages us to give up on public engagement, which simply broadens the gap.
          Maybe the situation is also different in different countries – here in Australia, it seems that there are a lot of ‘non-scientist’ public who are interested in science/environment stories, but perhaps don’t have the time, skills or the depth of interest to follow the story through to find out the rest, so they just go with the media report they first come across. Regardless, a journalist’s job objective is to report the unbiased truth, so that should be happening, whether people are interested in hearing it or not.

          • I don’t want us scientists to give up on communicating our work. I just wish for more realism in the expectations.

            With regard to differences between countries: that may well be. Although I don’t think that Germans are exceptionally science-averse, I would rather expect it otherwise (especially when comparing it with Poland, where I actually come from).

  2. Interesting post…as you say, it’s good that (some) wildlife can adapt to human detritus, but that shouldn’t stop us from attempting to clean up our act.

  3. Exemptionalists will claim this is just another example of how nature bends to our will, but it seems more sinister than that to me, we’re obviously doing an incredible amount of harm to this planet. Thanks for sharing

  4. Pingback: Plastic Bees | Honey Naturally

  5. There’s always a thirst for ‘positive’ news when it comes to environmental issues – but I think reporting like this is also the result of some news ‘content-providers’ simply having neither the time nor the understanding/willingness to put these stories in a genuine ecological context, or to discuss boring trivia like sample size.

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