Wax worm may answer problem of plastic waste

Wax worm may answer problem of plastic waste

And the wax worm discovery is still far from a solution to the world's piles of waste, says Susan Selke, director of the Michigan State University School of Packaging.

The wax caterpillar is the only known insect to be able to break down polyethylene in this way.

The promising discovery centres on the wax worm - the name for the caterpillar larva of Galleria mellonella, or greater wax moth.

A type of parasitic larvae often bred as fishing bait may hold a key to reducing the world's plastic waste, researchers say.

On April 24, the three researchers published their work in the journal Current Biology (http://www.cell.com/current-biology/fulltext/S0960-9822 (17) 30231-2 ), proving that wax worms do not only chew on plastic, but they feed on it. Wax moths deposit their eggs inside bee hives. The scientists propose that digesting beeswax requires the worms to break down chemical bonds in a process similar to breaking down polyethylene. So, no, plastic is not its natural diet!

People use one trillion plastic bags every year and scientists finally think they might have found something to degrade some of this waste - a caterpillar. She put the worms in a plastic bag, tied it closed, and put the bag in a room of her house while she finished cleaning the hive.

She put some worms in a plastic bag and noticed, a few minutes later, holes in the bag, large enough for the worms to crawl out. Less than an hour later, the bag was riddled with holes. A follow-up test using standard shopping bags weighing just under three grams each found that an individual caterpillar took about 12 hours to consume a milligram of such a bag. This resulted in a loss of 92 mg of material, or 13 percent of the sample's polyethylene content, being a faster process in plastic degradation than any other. While the highest density plastic takes up to 400 years to disintegrate.

"Wax is a polymer, a sort of "natural plastic", and has a chemical structure not dissimilar to polythene", Bertocchini suggested.

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However, just because the caterpillar offers a possible way to deal with plastic waste, it's not a reason to continue polluting, Bertocchini said.

The researchers conducted spectroscopic analysis to show the chemical bonds in the plastic were breaking.

However, it wasn't clear whether the caterpillar degraded the plastic simply by eating it, the researchers said.

The scientists also found that what the worms did transformed the plastic into ethylene glycol, which is commonly used in antifreeze.

Once the larval phase is over, the worms wrap themselves in their cocoons.

Bertocchini's team is hoping the worm contains an enzyme that they could then isolate and produce synthetically on an industrial scale.

To rule out munching action from their jaws as the source of degradation, the team applied a soupy blend of recently deceased worms to the plastic and waited. This is problematic because plastic does not break down easily and even when it is broken down into smaller pieces, it can negatively influence various ecosystems.