Galleria Mellonella Larvae as an Alternative to Low-Density Polyethylene and Polystyrene Biodegradation

The excessive plastics production and its inappropriate disposal contribute to unprecedented pollution. Galleria mellonella larvae were chosen as the object of this work, in order to evaluate its ability to biodegrade two types of plastics most common in everyday life: polystyrene (PS) and low-density polyethylene (LDPE). This research is one of the few that use PS and LDPE as the sole carbon sources in the diet of G. mellonella. We studied how contact with larvae affected both types of plastic, covering morphological, physicochemical and mass loss levels. In this particular work, twenty-five larvae were placed inside glass containers in direct contact with the plastics and incubated in the dark at 28 °C. The results showed that PS had greater biodegradation, indicating 56.12% mass loss, while LDPE was 5.11% degraded. After 7.25 days of testing, the larvae survival rate was 60% for PS and 82% for LDPE. The contact with the larvae changed the material wettability, being more noticeable on the PS surface. The formation of new chemical groups indicated the existence of biodegradation processes in the PS sample, but in LDPE no new bands were observed. After 7.25 days, we evaluated larval survival and pupal formation after contact with PS and LPDE, but no significant differences were observed between the groups. No significant difference on the survival and pupa formation of larvae exposed to both types of plastic was found. We conclude that G. mellonella larvae can be a cost-effective and promising alternative to biodegrade PS and LDPE pieces in plastic waste environments.