The researchers showed that the wax worms were not only ingesting the plastic, they were also chemically transforming the polyethylene into ethylene glycol.
The wax worm, the larvae of the common insect Galleria mellonella, or greater wax moth, is a scourge of beehives across Europe, laying their eggs inside hives where the worms hatch and grow on beeswax - hence the name. So when a colleague of Professor Chris Howe, at University of Cambridge, discovered wax moth caterpillars can eat plastic, they wanted to find out whether it could be a useful tool to clear up waste plastic. She temporarily kept the larvae in a typical plastic shopping bag, which then became riddled with holes.
The researchers said the molecular details of wax biodegradation require further investigation, but it is likely that digesting beeswax and polyethylene involves breaking down similar types of chemical bonds.
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. We showed that the polymer chains in polyethylene plastic are actually broken by the wax worms, ' said Bombelli.
As the molecular details of the process become known, the researchers say it could be used to devise a biotechnological solution to managing polyethylene waste.
A commercially bred caterpillar can quickly break down polythene bags and may help get rid of the plastic waste accumulating in landfill sites and oceans, scientists say.
The researchers, publishing their results in the journal "Current Biology", say that the degradation rate is extremely fast compared to other recent discoveries, such as bacteria reported a year ago to biodegrade some plastics at a rate of just 0.13mg a day.
'However, we should not feel justified to dump polyethylene deliberately in our environment just because we now know how to bio-degrade it, ' Bertocchini concludes.