The worm has turned… plastic bags into syrup

Biochemists in Madrid and Cambridge have found that caterpillars of the Greater Wax Moth eat carrier bags, leading to a simple biological answer to plastic pollution.

The larva could be used to solve the problem of plastic bag and sheet pollution, or their gut bacteria could be mass produced to destroy polyethylene.

The caterpillars are offspring of the Greater Wax Moth, a moth common across Asia and Europe which is bred for angling bait. The larvae, or Wax Worms, live as parasites in honey bee colonies in the wild, and are the bane of beekeepers as they hatch and grow on beeswax. Both beeswax and organic ethylene are ultimately derivations of palmitic acid, and the similarity of structures allows the caterpillar to produce an agent that breaks the chemical bond.  

Federica Bertocchini, an amateur beekeeper, discovered the effects of the larva by accident after removing them from her hives and placing them in a shopping bag, which was soon riddled with holes. She said: “Wax is a polymer, a sort of ‘natural plastic,’ and has a chemical structure not dissimilar to polyethylene.”

After noticing the caterpillar’s appetite for plastic, she set up an experiment with Paolo Bombelli from the Spanish National Research Council (CSIC) and Christopher Howe at the University of Cambridge’s Department of Biochemistry to conduct a timed experiment.

They placed a hundred wax worms on a plastic bag, and holes started to appear after just 40 minutes, and after 12 hours there was a reduction in plastic mass of 92mg from the bag.

Scientists say that the degradation rate is extremely fast compared to other recent discoveries, such as bacteria reported last year to biodegrade some plastics at a rate of just 0.13mg a day. Polyethylene takes between 100 and 400 years to degrade in landfill sites.

The researchers conducted spectroscopic analysis to show the broken chemical plastic bonds. The larva transformed the polyethylene into ethylene glycol, a monomer, which can be used as raw materials to make PET.

To confirm it wasn’t just the chewing mechanism of the caterpillars degrading the plastic, the team mashed up some of the worms and smeared them on polyethylene bags, with similar results.

Bertocchini concluded: “We are planning to implement this finding into a viable way to get rid of plastic waste, working towards a solution to save our oceans, rivers, and all the environment from the unavoidable consequences of plastic accumulation.”