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Biodegradation of Pristine and Post-Consumer Extruded Expanded Polystyrene Packaging by Zophobas atratus Larvae: Influence of the Larval Stage and Physiological Response

Journal of Materials Science 2025
Juraci Duarte Pereira, Jamille Santos Santana, Paulo Vitor França Lemos, Denílson de Jesus Assis, Carolina Oliveira de Souza, Lucas Guimarães Cardoso, Alessandra A. Lucas, Lívia Maria Garcia Gonçalves, Rita C. O. Sebastião, Bárbara Darós de Lelis Ferreira, Maria Betânia de Freitas Marques, Andrea Rebouças Rocha, Renata Quartieri Nascimento, Jania Betânia Alves da Silva

Summary

Researchers evaluated Zophobas atratus larvae (superworm beetles) as biodegraders of expanded polystyrene packaging, finding that larger larvae consumed more material while smaller larvae showed greater enzymatic activity, with both life stages reducing molecular weight and causing oxidative chemical changes. The study demonstrates that Z. atratus can biodegrade both pristine and post-consumer polystyrene, with degradation efficiency depending on larval developmental stage and substrate type.

Polymers

Plastics are inexpensive and widely used but persist in the environment due to improper disposal. Insect-mediated biodegradation has gained attention, notably involving Tenebrio molitor larvae. Despite morphological similarities and larger size, Zophobas atratus larvae remain less studied. This work evaluated the impact of larval stage on the biodegradation of pristine and post-consumer extruded polystyrene (XPS) and the physiological effects of an XPS-based diet. Smaller (L1) and larger (L2) larvae were tested. L2 showed higher XPS consumption, weight gain, and survival, while XPS-fed larvae overall exhibited reduced lipid content and increased moisture, flavonoids, and phenolics compared to wheat bran-fed controls. Scanning electron microscopy revealed surface fragmentation in frass, more pronounced in L1, suggesting greater mechanical or enzymatic action. High-performance size exclusion chromatography indicated molecular weight reduction, with L1 more effective on pristine XPS and L2 on post-consumer XPS, likely due to nutritional residues. FTIR analysis showed oxidative changes in both groups, more prominent in L1. Thermogravimetric analysis revealed earlier degradation onset in L1 frass, supporting the presence of oxidized oligomers. Overall, Z. atratus larvae can biodegrade XPS, with degradation influenced by developmental stage and substrate type. These findings inform biotechnological strategies for sustainable plastic waste management.

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