The most common form of plastic in use today is polyethylene. Whenever you use a plastic bag, plastic film or drink from a plastic cup or bottles, it’s probably made from polyethylene. And while it’s very useful, it also takes a very long time to degrade, with estimates ranging from 100 to 400 years if left in landfill.
Being able to degrade polyethylene quickly is a challenge, and one that so far scientists haven’t been able to overcome. However, an accidental discovery may be about to change that.
Federica Bertocchini is an amateur beekeeper and member of the Spanish National Research Council (CSIC). One of the beekeeper’s enemies is the wax worm caterpillar, which is the larvae of the greater wax moth. They take up residence inside beehives and live on the beeswax (they also make for great fishing bait). Beekeepers need to go in and remove them from their hives.
Bertocchini decided to temporarily store the wax worms she was removing from a hive in a plastic bag. But the bag did not stay secure for long as holes started appearing in it. Bertocchini reported her finding and began working with the University of Cambridge’s Department of Biochemistry to experiment with the plastic eating caterpillars.
What they discovered is wax worms are great at breaking down plastic. Where as bacteria can biodegrade plastic at a rate of about 0.13mg per day, 100 wax worms chomp through as much as 184mg per day. As to why they can do this, it’s thought to be related to their beeswax diet.
Wax is, according to Bertocchini, “a sort of natural plastic,” so the caterpillars are already setup to breakdown similar structures to our man-made plastics. And they don’t just eat it, they break the polymer chains in the plastic, allowing for true biodegradation.
Rather than throwing millions of caterpillars at the plastic pollution problem, the next step is to identify how the wax worms achieve this feat. It could be something in their saliva or gut, but whatever it is, identifying it means scientists could extract and reproduce it at scale so as to start quickly biodegrading waste plastic.