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Insect larvae contribute to microplastic pollution

According to a recent study led by the University of York, the larvae of Caddisflies – a common insect inhabiting freshwater environments such as lakes, rivers, and ponds – could be inadvertently contributing to microplastic pollution in rivers and waterways by chewing up plastic litter.

The scientists were amazed to find that these larvae used their sharp teeth to bite plastic into smaller pieces, which they then used to build the protective casing they live in until they reach adulthood. Despite presenting the larvae with a variety of alternative natural building material, they frequently chose to gnaw through plastic film, generating hundreds of microplastic particles in just a few days.

“Given the increasing concern for the effects of plastic pollution on our environment, we wanted to understand whether caddisfly larvae would interact with items of plastic litter which commonly pollute the environment, and determine what the consequences of these interactions might be,” said study lead author Katey Valentine, a doctoral student in Biology at York.

Valentine and her colleagues presented larvae with pieces of plastic film cut from a commercially available biodegradable plastic bag, along with pieces of oak leaf. Although the larvae often chose the oak leaf material, many of them seemed to prefer the pieces of plastic for building their new case.

“As well as demonstrating microplastic production, our work also shows how these organisms can exploit plastics to construct their homes. This could make the larvae more prone to predation and result in increased exposure to things like additives that will slowly leach from the plastic,” explained study senior author Alistair Boxall, a professor of Environmental Science at York.

“The active use of plastic litter by freshwater animals that our study uncovered could contribute to the formation of microplastics within these habitats. Further work is now needed to determine the extent to which these animals could be utilizing plastic litter and creating microplastics throughout natural freshwater environments globally, and whether other common freshwater species exhibit similar behavior,” Valentine concluded.

The study is published in the journal Environmental Toxicology and Chemistry.

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By Andrei Ionescu, Staff Writer

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