Wax worms take a liking to plastic shopping bags

Polyethylene plastic shopping bags are extremely cheap and useful, but they’re also a source of widespread pollution. A team led by biologist Federica Bertocchini of Spain’s Institute of Biomedicine & Biotechnology of Cantabria has discovered a very hungry caterpillar that eats the plastic, a finding that could turn out to be a solution to this dilemma. A hobbyist beekeeper, Bertocchini noticed that wax worm caterpillars had hatched and emerged on the panels of one of her hives. The worms are the larvae of the wax moth Galleria mellonella, which is known to infest beehives. The caterpillars were feeding on beeswax—hence their name. When Bertocchini went to dispose of the wax worms in a polyethylene bag, which is chemically similar to the long alkyl chain compounds that make up beeswax, the wax worms quickly ate through the plastic and escaped. Investigating further, Bertocchini and her colleagues found that enzymes produced by the wax worm or by bacteria in their digestive tract depolymerize polyethylene to produce ethylene glycol (Curr. Biol. 2017, DOI: 10.1016/j.cub.2017.02.060). Researchers previously found that related moth larvae can biodegrade polyethylene,beetle larvae known as mealworms can eat Styrofoam, and soil bacteria can munch on polyethylene terephthalate drink-bottle plastic. Because wax worms are grown commercially to use as fish bait and to feed household pets such as birds and turtles, Bertocchini suggests they could be put to work eating plastic waste, possibly recovering useful amounts of ethylene glycol. Alternatively, she says the responsible enzymes could be mass-produced and drizzled over plastic to degrade it, or the genes coding for the enzymes could be engineered into a bacterium applied to plastics.