Plastic eating worms could help deal with the plastic waste menace

Plastic has always been a good driver of industrialization and business, but it was not such a good idea when you see and think of the waste problem it causes. Plastic found its popularity in shopping and packaging arenas because it produced the cheapest packaging solution -- the plastic bag -- that is also very lightweight and manageable, and the combination of its good factors have made it difficult to replace -- even though there have been many attempts to ban its use in various jurisdictions around the world.

Shoppers across the world are now using about 500 billion single-use plastic bags per year, which is a huge amount. In other words, an average person now uses more than 200 plastic bags each year and these bags take between 100 and 400 years to degrade in landfills. Plastic bags are now in our faces everywhere we go: oceans, trees are adorned with tattered ribbons of shopping bags, in landfills, on roadsides and in waterways. They are non-biodegradable and very difficult to recycle -- especially in regard to collecting and sorting.

But the problem of plastic waste now has a potential solution if the news about discovery of plastic eating waxworms materializes. Scientists have discovered that the caterpillars residing in hives and that eat the wax from which bees make honey combs, could actually eat away polyethylene plastic! To be precise, 100 worms can devour 92 milligrams of polyethylene in only 12 hours according to the research. To explain further, each of the caterpillars ate an average of 2.2 holes, three milligrams across, every hour, in the plastic film. 

If you are wondering how many worms it would take to deal with the enormous amount of plastic that the whole world generates, let's take the example of the U.K., which alone generates 2 million tons of plastic waste every year. It would still take billions of waxworm caterpillars to eat the plastic away, even if they are eating constantly all year round.

The discovery of plastic eating worms was made by Federica Bertocchini, an amateur beekeeper who is also a biologist at Cantabria University.  She found that some worms were chewing holes through beeswax and then put those worms inside a plastic bag to carry them home for identification. She later found that the worms had made holes all over the plastic bag. This inspired her and her fellow scientists from Cambridge University (Paolo Bombelli and Christopher Howe), to start researching the feeding habits of the centimetre-long Galleria Mellonella grubs (waxworms): They found that the worms could help deal with a global crisis for which a lasting solution has not yet been found. 

The waxworms, which usually eat beeswax, are bred as fishing bait and their larvae sold as delicious snacks for chub, carp and catfish; eat plastic using the same enzymes they use to digest beeswax.

During the experiment, holes still appeared on the plastic paper bags even after the scientists mashed some worms and smeared the paste on the plastic paper bags, confirming that the worms were not simply cutting the paper bag into smaller pieces.

The research is now published in the journal  Current Biology.

Polyethylene and propropylene are the major constituents in plastic waste today. The scientists will now look into what type of enzymes the worms use to degrade these types of plastic.

The worms could be bred in large numbers in order to deal with what is now called the plastic menace, as long as these worms have a real viable appetite for plastic as food and not just in order to escape, said Paolo Bombelli, a biochemist at Cambridge who took part in the study.

“We want to know if they’re munching the plastic to use as a food, or just because they want to escape,” said Bombelli. “If they just want to escape, they are going to get fed up very soon. But if they’re munching it to use as an energy source it’s a completely different ball game. We are not yet able to answer this, but we’re working on it.”

But there are other questions that are yet to be ironed out, for instance whether the larvae actually derives any nutrient value from the plastic and if they are able to digest it, then what is the constituent in the feces; do they produce toxic waste after eating plastic or other constituents that might require scientists to pursue the matter? There is also another problem to deal with: these worms are airborne enemies of bees and can destroy bee populations by eating beeswax, meaning growing them in large numbers would present another difficulty for farmers who rely on bees for crop pollination. Again, how you would distribute these worms in order to devour plastic waste only is something that would need to be looked into through research.

But breeding those worms in large numbers in order to deal with the problem is not the only option scientists may have when deploying the solution. The genes could also be put into bacteria and marine organisms that would be dispersed to help degrade plastics, for instance. Scientists could, alternatively, look into extracting the enzymes and using them to degrade plastics separately or brewing up the bacteria in fermentation vats that would be used to dissolve plastics.

Previous research in using living organisms to get rid of plastic waste hasn't been very successful to say the least, with the closest thing to breakthrough being a bacterium -- Nocardia asteroides -- discovered recently, that can eat away a film of plastic but takes a long time to drill through even a mere half millimeter thick plastic film. In other words, waxworms could do a much better job. It takes the wax-moth caterpillars, or Galleria Mellonella, only 40 minutes to eat away the kind of film that Nocardia Asteroides would take half a year to deal with.

The Indian Mealmoth is another wax-eater  first studied in 2014 for similar properties - it has bacteria in its digestive tract responsible for breaking down polyethylene. Japanese scientists also last year found a bacterium that can feed on another common plastic, polyethylene terephthalate, which is used to make bottles for soft drinks and water.

Creatures like the humble waxworm could have a bright future as one solution to the plastic menace if current advances in research are confirmed.