Helicoverpa armigera (Lepidoptera, Noctuidae) as a reservoir of potential polystyrene-degrading fungi

A substantial portion of plastic waste is composed of polystyrene (PS). The polymer's end-of-life disposal is a concern due to its recalcitrant structure, which makes biodegradation difficult. Studies have shown that certain insect larvae are capable of ingesting, degrading, and mineralizing this material. This process is actively mediated by the intestinal larval microbiota, which comprises bacteria and fungi. The role of fungi is scarcely investigated, despite the extensive research conducted on the involvement of bacteria in the process.

The cotton bollworm (Helicoverpa armigera) was fed with expanded polystyrene (EPS), and the changes in the gut mycobiota were investigated. The ITS metabarcoding revealed that the yeast Diutina sp. was the most representative taxon in the samples, surpassing other taxa. Conversely, the feeding with EPS resulted in a decrease in the presence of Diutina sp. Additionally, four cultivable fungi (i.e., Aspergillus sp., Talaromyces sp., and two Penicillium species) isolated from the larvae's intestine were evaluated for their capacity to degrade PS. The fungi were cultured in low-carbon PDA and then covered with a PS film for 60 days. Scanning electron microscopy (SEM) analysis revealed that the fungi interacted with and altered the polymer's surface, resulting in the formation of cavities within the PS film.

These findings indicate that Helicoverpa armigera has the potential to serve as a reservoir for polystyrene-degrading fungi.