Plastic Bag Waste in the Oceans
Can simple wax worms cause the decomposition of polyethylene? Over three trillion single-use plastic bags are produced every year. Many of them find their way into our oceans. A large majority of these bags are made of polyethylene (PE). Polyethylene is a strong plastic that takes decades to break down. But it may be that the lowly wax worm can offer a solution to this massive problem.
Wax worms are commercially grown as food for humans in areas where meat is not readily available. The worms are the larvae of the Greater Wax Moth. They are used as well as live food for terrarium pets and some birds. However, most people will recognize them as food for captive reptiles such as bearded dragons, geckos, chameleons, turtles, hedgehogs, etc. Additionally, anglers use them as bait and refer to them as waxies. They are high in fat content, easy to breed, and can survive for weeks at low temperatures.
However, an accidental discovery may help scientists find a remedy for all that PE waste. Scientist and beekeeper, Federica Bertocchini, from the Institute of Bio-medicine and Biotechnology of Cantabria in Spain was tending her bees in her backyard. She had cleaned out a hive that was infested with wax worms and put the debris in a plastic bag. Shortly after she saw that the plastic bag was full of holes. The wax worms had escaped.
So, were the larvae just chewing through the plastic bag, or were they actually eating it and breaking it down chemically in their guts? Bertocchini and her team decided to test the alternatives. They ground up some worms and spread the resulting pulp on a polyethylene bag. The PE bag degraded. Clearly, a chemical reaction was going on and not just a physical breakdown.
Polyethylene Into Glycol
The larvae was actually causing the decomposition of polyethylene and turning it into glycol, a liquid. Glycol is an alcohol. Thus the experiment showed that polyethylene could be broken down by the worms into a different material.
The Enzyme in the Gut of Wax Worms
It is not clear how the larvae chemically break down the plastic. The worms like to live in beehives where they survive on wax and honey. Both beeswax and polyethylene have strong carbon bonds. It is possible it is not the worm itself that biodegrades polyethylene but an enzyme in the gut of the larvae.
Another group of scientists at Brandon University in Manitoba, Canada concluded that the micro-organisms in their guts did allow the wax worms to “ingest and metabolize” polyethylene at an impressive rate. Furthermore, the researchers found that wax worms could survive on a sole diet of polyethylene. The scientists dubbed them “plastivores.”
Releasing the live worms on plastic waste is not a viable solution. Wax worms are pests that like to feed on honeycombs endangering bees and the crops and the plants bees pollinate. And then what will we do with all that glycol they might produce? Researchers are looking for ways to harness gut bacteria to develop products or by-products that can be used to efficiently break down plastics. Therefore whole live larvae would not be required.