Scientists Discover Caterpillar That Actually Eats Plastic

About 500 billion plastic bags are used worldwide every year, and it takes between 500 and 1,000 years for plastic to degrade. Spencer Platt/Getty Images

Plastic bags — people use trillions of them every year, and they wreak a nasty toll on the environment. That's because the plastic they're made from is derived from fossil fuel oil that is difficult to break down, and they often end up polluting landfills and other ecosystems around the world. But scientists in Europe might have stumbled on how to rid the world of this pesky pollution problem — give the cleanup job to a tiny plastic-eating caterpillar

How the researchers made the discovery is one of those lucky accidents of science. Federica Bertocchini, an amateur beekeeper who also works at the Institute of Biomedicine and Biotechnology of Cantabria in Spain, was removing wax worms, the larvae of the wax moth (Galleria mellonella), from some hives. Wax moths commonly use the beeswax in the hives to lay their eggs.

Bertocchini put the parasitic pests from the honeycombs into a plastic bag, and a few hours later noticed the bag was full of holes. She enlisted colleagues at the University of Cambridge's Department of Biochemistry to investigate further, and put about 100 wax worms into a plastic bag from the supermarket. In less than an hour, they noted several holes, and after 12 hours, a significant amount of the plastic was gone. The results of their findings were published in the April 2017 issue of Current Biology.

But they also found that the worm, which is commercially bred for fishing bait, was not simply chewing holes in the bag and leaving tiny bits of plastic in its wake. Instead the team suspected something in the worms' systems was breaking down the chemical bonds in polyethylene, the synthetic polymer used to make the plastic bags. To confirm these findings, the researchers crushed some worms and smeared a worm paste on plastic bags and achieved similar results.

A wax worm is seen next to biodegraded holes in a polyethylene plastic shopping bag from a supermarket used by the researchers.
Paolo Bombelli

Just exactly how the worm breaks down the polymers in plastic remains a mystery, but scientists suspect an enzyme is involved. Beeswax is also a polymer, a type of "natural plastic" with a similar chemical make up as polyurethane. Researchers discovered that the enzyme changes polyurethane into ethylene glycol, a chemical used in antifreeze. Still, they haven't figured out whether the worm is producing the enzyme itself or whether it is produced by bacteria in the insect's gut.

Regardless, the implications of their findings could be enormous. If scientists can pinpoint the exact enzyme responsible for the chemical process, they might be able to reproduce it on a large enough scale to begin ridding the world of one of its major pollutants — plastic.