At a Glance
- Researchers discovered that caddisfly larvae have been incorporating microplastics into their protective casings since at least 1971, predating earlier estimates by nearly five decades.
- The study found microplastics in larvae from even pristine streams, indicating that plastic pollution had already reached remote freshwater ecosystems by the early 1970s.
- Analysis of the microplastics revealed man-made additives like titanium, barium, and lead, confirming their synthetic origin and long-standing presence in natural environments.
- The research underscores the value of natural history collections in revealing historical environmental changes through preserved biological specimens.
- The inclusion of microplastics in larval casings may increase their visibility to predators, raising concerns about the ecological impacts of long-term microplastic exposure.
A new study from the Naturalis Biodiversity Center in the Netherlands revealed that caddisfly larvae have been using microplastics to build protective casings for over 50 years. This discovery, published in Science of The Total Environment, pushes back the first known occurrence of this behavior from 2018 to 1971, 47 years earlier than previously thought. The researchers found microplastics in the casings of caddisfly larvae preserved in museum collections, with some specimens dating back to the 1970s.
Caddisflies, a moth-like insect, typically build their casings from materials like plant fragments or grains of sand for protection. However, as plastic pollution grew in the environment, the larvae began incorporating microplastics into their casings. The team discovered that these microplastics were present even in larvae from small, pristine streams, indicating that pollution was already affecting natural ecosystems at their very sources.
The researchers used advanced techniques to analyze the microplastics found in the casings. They found that the particles contained common plastic additives, such as titanium, barium, and lead. These chemicals are often used in plastic products, supporting the conclusion that the microplastics found in the caddisfly casings were man-made. This suggests that pollution has impacted freshwater ecosystems for decades before the issue became widely recognized.
This study emphasizes the importance of preserving long-term data in natural history collections, which can provide valuable insights into the history of environmental changes. The findings also raise concerns about the potential impact of microplastic pollution on wildlife. Microplastics in the caddisfly larvae casings, which are more visible and buoyant than natural materials, could make the larvae more vulnerable to predators, such as birds and fish, further highlighting the risks posed by pollution.
References
- Yirka, B. & Phys.org. (2025, April 18). Microplastics discovered in caddisfly casings from the 1970s suggest long-term contamination. Phys.Org; Phys.org. https://phys.org/news/2025-04-microplastics-caddisfly-casings-1970s-term.html
- Hiemstra, A.-F., van der Velden, I., Ciliberti, P., D’Alba, L., Gravendeel, B., & Schilthuizen, M. (2025). Half a century of caddisfly casings (Trichoptera) with microplastic from natural history collections. Science of The Total Environment, 974, 178947. https://doi.org/10.1016/j.scitotenv.2025.178947
