Host metabolic integration enables superior polystyrene degradation in cockroaches

Plastic pollution is a global crisis, with polystyrene (PS) among the most recalcitrant polymers owing to its stable aromatic structure and resistance to natural degradation. Although insect larvae such as mealworms and wax moth caterpillars can partially biodegrade PS through gut microbiota, reported rates remain low (0.08-0.24 mg per individual per day). The potential of cockroaches-with more stable gut microbiomes, longer lifespans, and greater biomass-for efficient, scalable plastic bioremediation has remained unexplored. Here we show that <i>Blaptica dubia</i> cockroaches rapidly biodegrade PS microplastics via a tightly integrated host-microbiota enzymatic network. Individuals ingested 6.0 ± 0.2 mg PS daily, achieving 54.9 ± 2.3% mass loss over 42 days and a specific biodegradation rate of 3.3 ± 0.1 mg per cockroach per day. Biodegradation was confirmed by substantial molecular-weight reductions (Mn 46.4%, Mw 25.9%) and isotopic mineralization signatures. PS exposure selectively enriched plastic-degrading taxa and enzymes while strongly upregulating host fatty-acid β-oxidation and tricarboxylic acid cycle pathways, enabling the host to directly metabolize microbial cleavage products and reconstruct a complete PS catabolic pathway. These findings reveal that <i>B. dubia</i> can far outperform other insects in plastic biodegradation through evolved metabolic cooperation, expanding the biological repertoire for tackling persistent anthropogenic polymers and offering new insight into insect adaptation to synthetic substrates in the Anthropocene.