Abstract:Plastic pollution is an environmental problem that has aroused global concern, and plastics degradation by insect gut microbiota is a new initiative to solve this problem. Despite the important role of insect gut microbiota in the degradation of plastics, little is known about the composition and dynamics of insect gut microbiota. [Objective] To study the effects of feeding plastics on the physiological indices and the composition and dynamics of gut microbiota in the larvae of four insect species. [Methods] Polystyrene (PS), polyethylene (PE), and wheat bran (control) were used as the sole carbon source respectively to feed the larvae of Zophobas atratus Fab., Tenebrio molitor L., Tenebrio obscurus F., and Galleria mellonella L. The dynamics of gut microbiota in the larvae of the four insect species were investigated by fluorescence in situ hybridization, and the correlations between the physiological indices and gut microbiota were analyzed. [Results] All four insect species fed with PS and PE had significantly lower body weight gain and body length increase than those in the control. The survival rates of Z. atratus and T. molitor larvae fed with PS were 25.33% and 11.75%, respectively, higher than those fed with PE. The dominant microbial taxa of the gut microbiota in the four insect species were Firmicutes (relative abundance of 16.98%-54.93%), Betaproteobacteria (5.91%-39.34%), Gammaproteobacteria (4.62%-30.86%) of Proteobacteria, and Euryarchaeota (9.99%-58.05%). [Conclusion] In addition to Firmicutes and Proteobacteria, archaea were also dominant in the gut microbiota in the larvae of the four species fed with PE and PS. The relative abundance of the main microbial taxa in the insect gut varied dynamically over time and was influenced by the types of plastics as well as the insect species. The body weights and body lengths of Z. atratus and T. molitor were correlated with their gut microbiota.
