Happy Garbage Meal!

Scientists stumble upon caterpillars that can eat plastic

FEDERICA BERTOCCHINI, a researcher who studies chick embryos, is a beekeeper in her spare time. She was cleaning some hives recently and found they were infested with waxworms, annoying pests for people who keep bees because their larvae chew through hives. “I put the worms in a plastic bag, and after a short while they were all around, and the plastic bag was full of holes,” says Bertocchini, who works at Spain’s Institute of Biomedicine and Biotechnology of Cantabria. Very few organisms are known to break down plastic, so she contacted collaborators Paolo Bombelli and Christopher Howe at the University of Cambridge, who study plastic biodegradation. To their surprise, the team found that the waxworms are capable of breaking down polyethylene, one of the most prevalent plastics in the world.

Their research, published in Current Biology, shows that waxworms can break the long carbon chain that makes up the backbone of the chemical. A few microbes have been found that are able to break down plastic, but they act much more slowly. The waxworms ( Galleria mellonella) produce holes in plastic within 40 minutes and can produce as many as three holes per hour.

The next job for the researchers: figure out how the creatures do it. Marion Brodhagen, a researcher at Western Washington University who wasn’t involved in this study, says the researchers haven’t proved that the “waxworm effect” isn’t merely a result of disintegration in their acidic intestines, or a mechanical process, and thinks they should have cleared this up before publishing. She also notes that a Chinese group has demonstrated that a microbe within meal moths, a distantly related species of waxworms, can digest polyethylene (but, again, slowly).

Identifying the biological mechanism responsible could help researchers attack plastic pollution, a scourge to freshwater sources and oceans. More than a trillion plastic bags are used every year on the planet, and most are not recycled.

Bertocchini says these caterpillars are likely able to break down polyethylene because it is similar to some of the waxy products present in beehives, which they infest.