From sprawling landfills to garbage flotillas, environmental pollution due to plastics is higher today than ever before. In response, Fraunhofer UMSICHT is performing research on environmentally-friendly processes for the decomposition of plastics, and has found that the humble mealworm’s unusual penchant for plastic could make it an unexpected ally in the fight against such waste material.

 

Global plastics consumption has risen 20-fold over the past half-century, and is expected to double again in the next 20 years. With low-cost and unrivalled functionality, the advantages of plastic are obvious, especially when it comes to protecting goods. Yet a report last year for the World Economic Forum claimed that a staggering 32 per cent of plastic packaging escapes collection systems. And be it plastic bottles, bags or cartons, many industrially utilised plastics are not decomposable in the environment, resulting in long-term pollution to our landscapes and bodies of water worldwide. 

 

Due to this sizeable and growing challenge, the decomposition of plastics in an environmentally friendly manner is seen as a topic of huge relevance amongst the research community. And in the fight against plastics waste, researchers are – in addition to micro-organisms, fungi, or isolated enzymes – now also increasingly utilising insects. Indeed, Spanish researchers were recently able to show that the larvae of the greater wax moth can decompose polyethylene (PE) plastics in a relatively short time – at least faster than bacteria in past tests. The combination of a mechanical disintegration by the insect's chewing tools and a subsequent microbial disintegration in the intestine is apparently particularly powerful.

 

Similar results have been demonstrated in the research of biology student Elma Mehovic, whose thesis at the Fraunhofer Institute for Environmental, Safety, and Energy Technology UMSICHT in Oberhausen (Germany) is focused on investigating the decomposition of polystyrene by mealworms. The plastics that are generated via the polymerisation of styrene find a wide variety of uses in the context of not only the thermal refurbishment of old buildings through thermal insulation, but also in the packaging industry, yet the humble mealworm in its immature form finds all formats equally delicious. “Mealworm larvae have different bacteria on their biofilm in the intestine that decompose the polystyrene,” pointed out Ms Mehovic, adding that, as a result, the mealworms can consume polystyrene without much effort and in the process decompose the plastics in a natural way.

 

From plastics to fish food

 

In the context of her thesis, Ms Mehovic is now trying to find out under which framework conditions the mealworm larvae optimally utilise the polystyrene. In this, the young researcher is predominanly interested in investigating the impact of ambient temperature and humidity on the feeding behaviour of the larvae. In a next step it is then to be checked whether the results from polystyrene can also be applied to other mass plastics. In a last step, Ms Mehovic will inspect and check the intestinal bacteria of the mealworm larvae to see to what extent it is possible to multiply them subsequent to an extraction and to utilise them in decomposition processes in the industry, in landfills, or in sewage treatment plants.

 

Such a prospect could be a game-changer for waste management, especially given that the impact of mealworm larvae is not only limited to the biological decomposition of plastics: “The larvae convert the polystyrene into biomass for their own organism. The mealworms can then, for example, subsequently be utilised further as high-quality fish food,” advised Ms Mehovic. Even if there are still numerous unanswered questions regarding the overall environmental balance or regarding a conceivable technical implementation, insects therefore appear to outline a promising and surprising new path in dealing with plastics waste.