Science Articles

The Caterpillar That Eats Plastic

The plastic eating caterpillar is not a means to an end. Hopefully it will lead to an end in itself.

In an exciting new development in the field of environmental science, Cambridge University researchers have discovered that the waxworm, found in beehives, can biodegrade polyethylene within hours. The discovery is ground-breaking, to say the least, as it offers a natural, viable solution to the unrelenting problem of plastic pollution facing the world today.

Around 80 million tonnes of polyethylene is used annually around the world. It is what your thin shopping bags and food packaging is made of, apart from being widely used in various industries. A single plastic bag can take at least a hundred years to decompose completely, going up to 400 years for the more resistant varieties.

Waxworms (scientific name- G. mellonella) is a common caterpillar found all over the world. It inhabits beehives, as beeswax and honeycombs are its primary source of food. After six-eight weeks of having hatched, the caterpillar spins a silky cocoon around itself, to emerge as a moth some weeks later.

The study’s senior researcher, Federica Bertocchini, a research scientist at the Spanish National Research Council (CSIC), who also works at the Institute of Biomedicine and Biotechnology of Cantabria, in Santander, Spain, stumbled upon the discovery by chance. An amateur beekeeper, she was cleaning out the honeycomb panels in her beehive when she came across these worms and put them into a plastic bag for discarding. Surprisingly, the waxworms ate their way out of the bag in under an hour, leaving the bag peppered with holes.

“This project began there and then,” Bertocchini said.

Further research into the discovery revealed that the worms could break down the chemical bonds of plastic during digestion, much in the same way they could digest beeswax. During the process of digestion, the caterpillars chemically converted the polyethylene into ethylene glycol. Ethylene glycol is used as an anti-freeze and coolant in various industries.

One hundred wax worms can biodegrade 92 milligrams of polyethylene in 12 hours, which is quite fast when seen in the context of the difficulty in decomposing plastic. Delving further into the discovery, they then put the chrysalis of the caterpillar against a piece of plastic. Amazingly, they found that the chrysalis also biodegraded the polyethylene.

These findings made the researchers hypothesize that the caterpillars produce an enzyme that can degrade the plastic when they eat it, or when it rubs against them or their chrysalis.

The next step in taking this discovery to its logical end will be to identify that enzyme, isolate it and produce it on an industrial scale, so that it can be put to use as soon as possible to successfully eliminate the scourge of plastic pollution.

And even if this discovery results in a sustainable solution that can be implemented widely across the world, it does not give us the license to start using plastic even more indiscriminately and irresponsibly and deliberately.

The plastic eating caterpillar is not a means to an end. Hopefully it will lead to an end in itself.