Preliminary Observations on the Use of Microplastics by Aquatic Larvae of the Moth Cataclysta lemnata (Linnaeus, 1758)

The interaction between freshwater biota and microplastics (MPs) has recently been described, mostly focusing on indoor experiments using fish, crustaceans, and chironomids. Among aquatic invertebrates, although having an important ecological role, aquatic butterfly larvae have not yet been investigated concerning plastics. We examined the interaction between aquatic larvae of the moth Cataclysta lemnata (Linnaeus, 1758) and MPs. We verified if (i) larvae could use MPs to build their protective cases, (ii) they could chew PVC, and (iii) there were effects on the pupae emergence to adult moths after larvae exposure to PVC. By performing two indoor experiments, (i) we exposed larvae to different MPs polymers, aquatic plant Lemna minuta, and a mix of MPs with L. minuta, and (ii) exposed larvae to a PVC layer. For the first time, we observed that C. lemnata larvae use MPs to build their cases and chewed the PVC layer. About half of the larvae (48.0%) pupated of which 43.7% emerged as adults. Our findings suggest that MPs are used by C. lemnata larvae, potentially affecting their life cycle. Future studies should explore whether MPs are transported by adult moths, linking aquatic and terrestrial ecosystems.