Nematodes Exhibit Learned Preference for Contaminated Food from Microplastics

In a groundbreaking study conducted by researchers at the Hong Kong Polytechnic University, it has been demonstrated that nematodes can develop a preference for food contaminated with microplastics after multigenerational exposure. This phenomenon, which reverses their natural food preferences, raises significant concerns about the implications of microplastic pollution on ecological and food web dynamics. The findings were published in the journal *Environmental Science & Technology Letters* on July 22, 2025, under the title "Microplastics Alter Predator Preferences of Prey through Associative Learning" (Yang et al., 2025).

The study highlights how organisms, particularly nematodes, assess food based on various sensory cues, including taste, odor, and texture. These cues are critical for avoiding harmful substances. However, the prevalence of pollutants like microplastics in ecosystems has complicated these natural evaluation processes. Microplastics, due to their small size, are often mistakenly ingested by small organisms, leading to unintended consequences. The research focused on *Caenorhabditis elegans*, a model organism in biological studies, to test whether these nematodes could distinguish between contaminated and uncontaminated prey.

During the experiments, nematodes raised on a diet including polystyrene microplastics were conditioned over successive generations. Although initially, they showed a preference for uncontaminated food sources, this behavior shifted as they adapted to their altered diet. After three generations of exposure to contaminated prey, the nematodes began to prefer the food that was previously deemed harmful. This behavioral adaptation requires functional olfactory learning, indicating the involvement of specific genes such as lrn-1, which is associated with olfactory associative learning, and odr-10, critical for detecting odors.

According to Dr. Amber Huizi Yang, lead author of the study and a researcher at the Hong Kong Polytechnic University, the implications of these findings are profound. "These conditioned preferences could disrupt normal predator-prey interactions and nutrient flow within ecosystems," she stated. The study's authors expressed concern that such changes might lead to altered food web structures, as predators trained to consume contaminated food may significantly shift prey distribution and abundance.

The research contributes to a growing body of evidence indicating that microplastics not only pose direct health risks to wildlife but also influence ecological dynamics through learned behaviors. The genetic basis for these behavioral changes underscores the critical need for further research into the long-term ecological effects of microplastics on various organisms and ecosystems.

In conclusion, the study sheds light on the adaptability of nematodes in the face of environmental stressors like microplastics, revealing how pollution can reshape natural behaviors and food preferences. As microplastic pollution continues to infiltrate ecosystems worldwide, understanding its impact on biodiversity and ecological relations becomes increasingly urgent. Future research should focus on the broader implications of these findings, particularly in terms of conservation strategies and ecosystem management in polluted environments.