Exposure to microplastic makes animals want to eat it more
NEMATODS worms can learn to prefer contaminated plastic prey to cleaner foods
Heiti Paves / Alamy
Predators can learn to prefer to eat prey contaminated by microplastics, even when clean foods are available. This behavior could have implications for eating habits and the health of whole ecosystems, including humans.
The researchers discovered this preference for plastic after studying the eating habits of small rounds called nematodes (Caenorhabditis Elegans) over several generations. When they offered them their usual food diet, as well as the same microbes contaminated by microplastics, the first generation of nematodes opted for the cleaner alternative. However, exposure to plastic lace -up foods over several generations has changed their preferences.
“They actually begin to prefer contaminated food,” explains the song Lin Chua at Polytechnique University in Hong Kong.
Why have worms develop a taste for plastic? As creatures without real vision, nematodes are counting on other senses to locate their food, such as smell. “Plastics can be one of these odors,” says Chua. After prolonged exposure, they can recognize microplastics as “more like food” and choose to eat them, he said. He speculates that other small animals that count on the smell to locate prey could “be confused” in the same way.
Chua stresses that behavior looks more like a learned response “than a genetic mutation, and therefore potentially reversible.” It is more like a question of taste, “he says, compare conditioning to human affinity for sugar. He says that in theory, this could be reversed in future generations, but that it always deserves a more in-depth study.
As one of the most common types of animals in the world, the food preferences of nematodes could have much more important implications for the health of their ecosystems. “These interactions of something that eat something else are really important to recycle and transform different forms of matter and energy,” explains Lee Demi to Allegheny College in Pennsylvania, which calls for “alarming” discovery.
“This will pass in the food chain,” explains Chua, who notes that behavior could create a kind of “training effect” that will also affect human food. “Finally, that will always come back to us,” he says.
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