Because nature always finds a way. Even in a lab.
As noted on Plastics Europe, plastic packaging made of Polyethylene (PE) represents ∼40% of total demand for plastic products with over a trillion plastic bags used every year. Up to 38% of plastic is discarded in landfills (while referring to EU countries, Norway and Switzerland), while 26% is used for recycling and 36% for energy recovery via combustion, which is something that represents a very heavy burden on the environment.
Researchers at Cambridge University tackled the issue, eventually discovering that the larvae of the wax moth Galleria mellonella, which feeds on wax in bee hives, is capable of degrading plastic. As published in the online article at Current Biology, when a PE film was left in direct contact with wax worms, holes started to appear after 40 minutes and made the researchers wonder, what exactly is it that allows the wax worm to degrade a chemical bond that's normally non-bio-degradable.
They wrote: "The answer may lie in the ecology of the wax worm itself. They feed on beeswax, and their natural niche is the honeycomb; the moth lays its eggs inside the beehive, where the worms grow to their pupa stage, eating beeswax. Beeswax is composed of a highly diverse mixture of lipid compounds, including alkanes, alkenes, fatty acids and esters. The most frequent hydrocarbon bond is the CH2–CH2, as in PE (Figure S1B). Although the molecular details of wax biodegradation require further investigation, it seems likely that the C–C single bond of these aliphatic compounds is one of the targets of digestion. The appearance of holes when PE films are left in direct contact with wax worms, and the FTIR analysis of degraded PE, indicate chemical breakdown of the PE, including breakage of C–C bonds."
More research is to be done, but the proof is there - caterpillars of wax moth can, in fact, bio-degrade plastic. Even if this sounds like a magical solution that will make everyhting right again, it doesn't mean we can now stop caring about what happens to our plastic waste. It still needs to be, by all means, avoided altogether or disposed of in a nature-friendly way.