Wax Worm Eats Plastic: New Waste Management Method?

The wax worm (caterpillar) has been found to eat plastic. The discovery, documented in a paper published in Current Biology, might pave the way to a fast and effective method to get rid of polluting plastic.

A wax worm eating plastic whose debris (polyethylene debris) can be seen on the creature. Photo credits: Federica Bertocchini, Paolo Bombelli, and Chris Howe.

Plastic: Food for Worm

Turns out there is a type of plastic that can be easily biodegraded. New scientific findings reveal that the wax worm can consume one of the toughest, and also most-commonly-used, plastic called polyethylene; this is what we usually use as shopping bags which often end up in ecosytems, polluting the environment. The researchers behind the new paper believe this larva could help them curb plastic pollution.

Let us learn more about the wax worm

It is the caterpillar to the greater wax moth known as Galleria mellonella. It is commercially bred to be used as fish bait. In the wild, the worm functions as a parasite living among bees. The wax moths lay their eggs in beehives which become the birthplace of their young. Upon hatching, the wax worms remain in the hive, feeding on honey and beeswax, which earns them their name. So, no, plastic is not its natural diet!

Holes in Plastic Bags

How did the scientists find it eating plastic, then?
It all started when amateur beekeeper, Federica Bertocchini, got rid of the parasitic worm from her beehives into a plastic shopping bag. She later spotted holes in the bag. Bertocchini, who works at the Institute of Biomedicine and Biotechnology of Cantabria (CSIC), Spain, then, conducted experiments, working in collaboration with a team from the University of Cambridge.

The scientists, led by Bertocchini, exposed a group of around 100 wax worms to a plastic shopping bag. Merely 40 minutes later, holes began appearing in the bag. It took only 100 wax worms to biodegrade 92 milligrams of polyethylene in 12 hours. The degradation of the material is deemed to be relatively extremely fast; bacteria biodegrading plastic are reported to do it at a much slower pace: 0.13 mg per day. To better appreciate the worms biodegrading the plastic at this speed, consider this: polyethylene plastic bags take around 100 years to disappear completely through decomposition. The toughest form might even take 400 years to be broken down. The existing methods, involving corrosive liquids, take several months, and are very painstaking.

Plastic is like Beeswax

The molecular pathways through which the biodegradation happens have not been deciphered yet; the researchers have not identified the molecules involved. The researchers are of the opinion that the worms might be feeding on the plastic in the same way they feed on the beeswax; according to them, the digestion of both might entail the breaking of similar chemical bonds. As lead author Bertocchini says, wax is a form of “natural plastic”, with a chemical structure not different from that of polyethylene.

Spectroscopic analysis showed the breaking of the chemical bonds that hold the plastic together. The worms would turn polyethylene into ethylene glycol.

“The caterpillars are not just eating the plastic without modifying its chemical make-up. We showed that the polymer chains in polyethylene plastic are actually broken by the wax worms,” says
study first author Paolo Bombelli.

In other words, the wax worms are not just ingesting the plastic, but also digesting it. Bombelli explains that the chemical bonds of the plastic could possibly be broken down by a substance either present in the salivary glands of the insect or secreted by the worm’s gut bacteria.

Cocoon of Wax Worm

The wax worm also works wonders as a cocoon. After the larval phase is over, it surrounds itself in a cocoon or chrysalis, which can also biodegrade plastic when in contact with it.

Bertocchini also talked about their plans to apply the knowledge they gleaned by producing a viable method to get rid of plastic. Plastic is notorious for its great resistance against degradation. Even when it is broken down into smaller pieces, it still harms ecosystems. Preivous biotechnological attempts to degrade it are inadequate. So, the unprecedented findings are deemed very promising. Polyethylene plastic waste clogging landfill sites might be removed using a method based on the wax-worm-biodegradation. This should be feasible by reproducing the enzyme (which, however, remains unknown) behind the chemical process on a large scale.

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