African mealworms may hold the key to plastic pollution

By studying these natural "plastic eaters", scientists hope to create new tools that will help get rid of plastic waste more quickly and efficiently

Researchers are hailing it as a fantastic discovery in the war against plastic waste: mealworm larvae that can eat polystyrene, also known as Styrofoam. The tiny insects join an elite group of bugs that had previously been discovered, which could help provide a solution to plastic waste.

This is the first insect species from Africa that has demonstrated this capability.

The problem with polystyrene

Polystyrene is a plastic that is commonly used in food packaging, electronics, and industrial materials and does not break down easily; its life, so to say, is measured by decades. Traditional methods of recycling by chemical or heat treatments are prohibitively expensive and often result in additional pollutants.

This level of complexity has led researchers to seek biological approaches to cope with such obdurate waste materials.

The study

Recently, a team of scientists from the International Centre of Insect Physiology and Ecology has found that Kenyan lesser mealworm larvae can chew through polystyrene. These larvae also harbor gut bacteria to help them break down the material.

The lesser mealworm is the larval form of the darkling beetle Alphitobius, having a larva for 8–10 weeks. These insects are common in poultry farming environments.

While lesser mealworms are thought to have originated in Africa, they can now be found everywhere in the world. The species found in our research could be a subspecies of Alphitobius. Further research is underway to confirm this hypothesis, said the researchers.

Their study also explored the insect’s gut bacteria, focusing on microbial communities that could support such a plastic degradation process.
A solution to Africa’s plastic crisis?

Plastic pollution is critically high in some African countries. Although the problem of plastic waste is global, Africa has taken a particularly hard hit, not least because of the high volume of imported waste.

“By studying these natural ‘plastic eaters,’ we hope to develop tools for faster and more efficient waste management,” said the researchers.Instead of dumping millions of these insects into waste disposal sites-which would be highly impracticable-scientists foresee the microbes and enzymes produced by these insects being used in an industrial process, landfill, and cleanup efforts that could make large-scale plastic waste management possible.

Bacteria behind the magic

The authors indeed found that the guts of larvae fed polystyrene were rich in the Proteobacteria and Firmicutes, bacteria able both to settle down in all kinds of environments and degrade almost any complex material. This apart, there were Kluyvera, Lactococcus, Citrobacter, and Klebsiella-all known to produce enzymes capable of digesting synthetic plastics.

“These bacteria are not harmful for this insect or for the environment if applied on a big scale,” the authors underline.

These bacteria may indicate a vital role in plastic decomposition. Intriguingly, it seems that the larvae do not inherently have the capability of digesting plastic. Rather, their gut bacteria seem to modify in response to plastic exposure, allowing breakdown to occur.

These findings support our hypothesis that the gut microbiome of certain insects facilitates plastic degradation. This likely occurs because their gut bacteria can produce enzymes that break down plastic polymers, the researchers said.

The potential to isolate these bacteria and their enzymes could pave the way for microbial solutions to plastic waste on a larger scale. The Kenyan mealworm’s ability to consume polystyrene suggests it could play a role in naturally reducing plastic waste, particularly for materials resistant to conventional recycling methods.

Future research could isolate and identify specific bacterial types that take part in the degradation of polystyrene and analyze their enzymes. On the other hand, such research could be long-term.