Polyester Bees

Life with plastic, it’s fantastic. If humans don’t tell you so, just ask these bees.

We often look to see what makes us human; what separates us from the rest of the animal kingdom. There are almost countless quick answers—language, tool use, philosophy. These have a tendency to fall apart fairly quickly, though: Alex the parrot could famously use language, and chimpanzees use tools too. An ape Aristotle or Socrates among the sealions may be a step too far, but don’t count on it.

One answer to this question that surely, no one will dispute, is plastic. Of course we’re the only ones who make, use, and then discard plastic. Right?

Not quite.

While the blame for pollution and the terrible state of the world’s oceans might be completely on us, we aren’t the only ones living life in plastic.

Enter Colletes bees. These tiny, enterprising creatures are ground nesters. They spend their lives creating burrows for their offspring to grow to adulthood: a seemingly endless graft. This is a tedious enough task on its own—these burrows can be up to burrows can go down as deep as half a metre, or fifty times the length of a bee. But take a closer look at what they’re working with. They aren’t simply digging out homes using earth and intricate craftsmanship. Once done, they’re sealing those tunnels with a form of—you guessed it—our own supposedly unique invention, plastic.

Plastics have become the ‘bogey materials’ of our age: rarely a day goes by without some horror story on the latest potential environmental catastrophe that may be brought about by human addiction to their favourite polymer-based creations.

Putting the horrors of human excess aside for a second, though, it’s worth remembering that plastics have become ubiquitous for a reason. They have so many useful qualities, the main two being that they’re tough and extremely mouldable. Because they have so few additional features, we can shape them to form literally anything we want—be it thin cellophane wrapping or a sturdy pipe for water transportation.

Colletes also grasp the intrinsic value of plastics.

In a sense, our subjects, aptly known as polyester or plasterer bees, are rather like the vast majority of bees, which is solitary – building nests or individual egg chambers for their brood alone, then provisioning them with pollen and nectar to give their larvae the best chances of making it to adulthood. The term ‘bees’ usually brings to mind beehives, but that’s because most people are thinking of honeybees. In reality 90% of bee species follow an independent lifestyle—although the formidably well-sealed nests of Colletes certainly set this genus apart.

A lot of effort goes into making Colletes nests structurally solid, which makes sense because most of them are ground-nesters. They follow a pattern of burrowing, tamping the surface of the burrow down, and sealing it with their plastic film.

And then doing it again, and again.

Female Colletes lay one egg per cell, which makes this a very elaborate process that must be repeated. Demanding work, one must admit. (Male polyester bees, as per the insect world in general, broadly-speaking, are only good for one thing: genes). Securing the walls with plastic like this keeps young Colletes safely sealed away from the harsh outside world, and gives them greater protection against any unexpected sub-surface movements. Ultimately, a cellophane-like seal provides more of an insurance policy than leaving bare earth as the barrier around growing juveniles.

So how do these bees come up with such an idiosyncratic construction material? Part of the story lies in a part of the female bee known as the Dufour’s gland. This gland is found in several other kinds of insect as well, and is associated with sting apparatus. In bees, it can represent 20-50% of their abdominal cavities, accounting for 10% of their weight. Apart from venom production, the Dufour’s gland also secretes chemicals used for communication—such as to signal the presence of a queen bee, or, in the case of ants, to mark down a victim.

But while the Dufour’s gland is an organ of pivotal significance to the life cycle of these bees, research shows that the smooth, hardened nature of the nest linings isn’t entirely down to what is produced here. Salivary secretions, and the chemical reaction between the two, are what make for some of the more impressive insect constructions even among the master builders of the Apidae.

It should be noted that bioplastic isn’t the only ingredient of Colletes nests. Scientists have found that the nest-making process starts with laying down silk fibre. The polyester is then added on top, making a material not unlike fiberglass.

Perhaps “polyester-silk bees” is just a bit too much of a mouthful.

Just how tough are the egg cells produced by this process? To find out, scientists tried dissolving them down in a lab...and found that they couldn’t.

No aqueous or organic solvents could render the eggs into their constituent parts, while basic and acid hydrolysis wouldn’t do the job either. As Debbie Chachra, the associate professor who found out about the silk-polyester approach, attested, “We found ourselves in this catch-22: anything nasty enough to break them down was too nasty to put into our equipment and anything we could put into our equipment wouldn’t break them down.”

That’s one way to put humans off the case of turning your evolutionary innovation into intellectual property – if only for a while. The hardcore nature of these bees’ handiwork has inevitably led to speculation about whether these might be biologically-derived materials we could make use of.

The nest-liner does, eventually, biodegrade, though it takes about five years to do so. This means there is some potential here for a Tupperware we can feel better about using. The bad news is, this won’t be for some time, as bioplastics are still a fair way from the mainstream, and what bees have evolved to produce naturally is proving to be rather more difficult to simulate in laboratories.

Coming up with perfect plastic alternatives is far from simple. So far, there have been as many misguided ideas and marketing gimmicks as there have been truly viable options, and bioplastics certainly haven’t escaped rightful criticism.

Biodegradable materials still need the right conditions to be able to do what they say on the tin, and many current facilities just aren’t up to the job. Bioplastics, to date, have tended to be produced from plants, which has also led to questions about the overall impact of their production process, especially around sustainable land use. If polyester bees do ultimately give up their secrets, and a way is found for their techniques to be mass-produced, how exactly the material is synthesised will need to be closely scrutinised.

Let’s end where we started. The irony is that the ‘alien’ qualities of arthropods, those wildcards that don’t lend themselves to anthropomorphism, are often those of most interest for commercial exploitation. Colletes are certainly not the only strand of the insect world with a commitment to better living through chemistry – and also not the only hymenopteran which will likely come under increased scrutiny from the scientific community.

Insect organs are multi-functional things, producing and utilising a cornucopia of compounds. We, the so-called masters of invention, have much to learn.