No evidence for behavioral or physiological effects of nanoplastics ingestion in the fruit fly Drosophila melanogaster

Plastic pollution increases worldwide, releasing small plastic particles into the environment, such as nanoplastics (NP) that affect living organisms. NP can penetrate biological membranes and interact with cellular components such as mitochondria. However, the effects of NP on terrestrial insects, the most diverse and abundant taxa, remains poorly studied compared to aquatic species. Our study assesses the effect of nanoplastics on the emergence rate, mitochondrial activity, metabolism, body mass, and locomotor activity in Drosophila melanogaster (Meigen, 1830, Diptera: Drosophilidae), a terrestrial insect. Three experimental groups were compared: a control group (C) with flies fed food without NP, a low contamination group (LOW) with flies fed food containing 1 µg/g of NP of different sizes (20, 80 and 200 nm), and a high contamination group (HIGH) with flies fed food containing 500 µg/g of NP of the same classes of sizes. Low and High groups were exposed to polystyrene NP for their entire development cycle. NP ingestion did not affect the number of pupae and adults, emergence rate, mitochondrial activity, metabolism and body mass. The locomotor activity of the flies was also unaffected by ingestion of NP. These results, compared with those reported in the literature, showed that the effect of nanoplastics on living organisms might depend on the species and polymer nature. The absence of detectable effects on flies is positive for the ecology of the species, constantly exposed to plastic pollution. Further studies in this area are still needed to fully determine the effects of NP on Drosophila biology and behavior.