Can animals help us solve our plastic problem?
March. 10, 2020
The larvae of the greater wax moth can eat polyethylene. This is the primary plastic found in single-use grocery bags. Scientists studying insect’s gut mechanism to help develop a tool to biodegrade plastic waste.
Scientists looking to find ways to tackle the world’s mounting plastic waste problem are hoping a caterpillar with an unusual diet can help.
More than 50 species of plastivore – small organisms that consume plastic – have been discovered, which are mostly bacteria and fungi but include some insects capable of turning plastic waste into energy.
Of particular interest to scientists at Brandon University in Manitoba, Canada, is the waxworm – the larval form of the greater wax moth. Its gut can digest plastic, and researchers are trying to understand why and how this happens.
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Approximately 9 billion tonnes of plastic has been produced since 1950 , but only 9% of this has ever been recycled, leaving many landfill sites overflowing, rivers polluted and huge patches of debris floating in our oceans .
Scientists think studying how waxworms break down plastic could help them create a natural solution to this problem.
Waxworms are pests that invade beehives and eat the honeycomb. And while the larvae are bad news for bees, they could be good news for us. The molecular makeup of honeycomb wax consists of long chains of carbon and hydrogen, which are similar to polyethylene – the primary plastic in items such as single-use grocery bags.
“The waxworm and its gut bacteria must break down these long chains (in honeycomb),” study author Christophe LeMoine told Discover Magazine . “And presumably, because plastics are similar in structure, they can also co-opt this machinery to use polyethylene plastics as a nutrient source.”
It takes about 60 waxworms an entire week to munch through a small square of thin plastic from a grocery bag, however, so unleashing billions of wriggling larvae on the world’s waste plastic is unlikely to be the answer.
If scientists can discover how eating plastic enhances waxworms’ gut bacteria, though, LeMoine says they may be able to design “the perfect plastic biodegradation system”.
Waxworms aren’t the only plastic-eaters researchers are observing. It’s been found that mealworms, for example, can digest plastic and still be nutritious food for other animals.
And scientists have discovered a species of coral that cleans microplastics from the ocean too.
Mushroom corals are common in the shallow waters around the Maldives . Researchers studied one species in an area in which they described the amount of plastic pollution as staggering – and discovered the corals could ingest tiny fragments of plastic.
Even more particles get stuck to the coral’s rough surface, helping to further sequester microplastics from the water. The researchers say this could, in part, help explain why, despite millions of tonnes of plastic ending up in the ocean, microplastics measuring under 1mm are found in much lower concentrations than expected in surface waters.
But the corals could pay a heavy price for this cleaning, with the researchers noting that both this ingestion and adhesion could have a negative impact – further threatening a species that, by helping protect coastlines and providing a habitat for other animals, is vital to marine ecosystems.
The economic damage plastic pollution causes to marine ecosystems is estimated to reach around $13 billion every year, according to the United Nations.
Plastic accounts for 80% of all ocean debris but only about 1% of this waste floats in surface waters. The majority sinks, breaking down into microplastics , where it is ingested by marine animals, entering the food chain and potentially threatening food security.
Greater understanding of how waxworms and other organisms are able to break down plastics could help provide a solution to reduce plastic waste. But resolving the issue on a global scale must involve a rethink of how we produce, use and manage plastics, so less is made, less is used and any waste is better managed.
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