Kenyan lesser mealworm larvae can digest polystyrene, study reveals

A study published in the journal Scientific Reports reveals that the larvae of the Kenyan lesser mealworm, scientifically known as Alphitobius diaperinus, have the ability to consume and degrade polystyrene, offering a promising solution in the fight against plastic pollution. Researchers from the International Centre of Insect Physiology and Ecology (icipe) have discovered that these larvae can chew polystyrene, a common plastic found in Styrofoam containers and packaging materials, and break it down in their guts with the help of intestinal bacteria.

"This is the first recorded instance of lesser mealworms, specifically from Africa, being able to digest plastic," stated study author Dr. Fathiya Khamis. The larvae were able to consume nearly 50% of the polystyrene they were fed during the trial period, a significant finding given the complex and resistant nature of plastic polymers. The efficiency increased when the plastic feed was mixed with bran or grain husks, indicating the importance of a nutritious diet for optimal plastic degradation.

Analysis of the larvae's intestines revealed significant changes in bacterial composition depending on their diet. Larvae fed polystyrene had higher levels of Proteobacteria and Firmicutes, suggesting these bacteria play a fundamental role in the degradation process. A consortium of bacteria in the intestines, including types called Kluyvera, Lactococcus, and Klebsiella, produces enzymes capable of breaking down the long chains of polystyrene. These enzymes transform the plastic into simpler compounds that the mealworms can safely digest without compromising their health.

Evalyne Ndotono, a PhD fellow at icipe, commented on the findings: "Our study has shown that mealworms can ingest nearly 50% of polystyrene. Our goal is to conduct more studies to understand the process through which mealworms consume polystyrene and whether they gain any nutritional benefit from this material." She added, "We will also explore the mechanisms of the lesser mealworm's bacteria in plastic degradation. We want to understand if the bacteria are inherent to the mealworms or if they are a defense strategy acquired after feeding on plastic."

This discovery represents a promising and sustainable alternative for plastic waste management, particularly in Africa, where plastic pollution is critically high due to rapid plastic use and low recycling rates. Despite producing only 5% of global plastic pollution, Africa is the second most plastic-polluted continent, suffering from the increasing use of single-use plastics that are discarded quickly. It is estimated that between 19 to 23 million tons of plastics end up in oceans, rivers, and lakes annually, contributing to a pollution crisis that affects both biodiversity and human health.

Traditional methods to recycle polystyrene, such as chemical, thermal, and mechanical processes, are expensive and produce toxic compounds harmful to humans, the environment, and biodiversity. Polystyrene, also known as Styrofoam, is a pollutant that runs rampant in aquatic ecosystems and is notoriously durable, making it resistant to conventional recycling methods. This has pushed researchers to explore biological solutions to manage polystyrene waste.

By studying these natural "plastic eaters," researchers hope to develop new tools to manage plastic waste more efficiently. Rather than releasing a large number of insects into waste sites, microbiomes and enzymes produced in factories, landfills, and cleanup sites could be used to tackle plastic waste on a large scale. Understanding shifts in bacterial composition is crucial because it reveals which microbes are actively involved in breaking down plastic, supporting the potential for large-scale management of plastic waste.

The potential for implementing this process on a large scale still depends on further research. Scientists will investigate the ability of the lesser mealworm to degrade various types of plastics and convert them into useful and safe products. Additionally, the use of bacteria isolated from the larvae to create customized microbial solutions for plastic degradation is an interesting possibility.

Research on these insects could lead to innovative solutions to address plastic pollution on a large scale, offering hope for a more sustainable future. The study conducted by icipe brings an innovative solution by exploring the digestive capacity of mealworm beetle larvae, which have demonstrated a surprising ability to biodegrade plastics.

The Kenyan lesser mealworm's ability to consume polystyrene suggests it could play a role in natural waste reduction, especially for plastics resistant to conventional recycling methods. Further research could explore new applications for waste management and ensure the safety of the insects and the produced biomass.

Sources: Liputan 6, El Economista, Rio Show, O Globo, El Colombiano, Scienze Notizie

This article was written in collaboration with generative AI company Alchemiq