Antibiotics ingestion altered the composition of gut microbes and affected the development and reproduction of the fall armyworm

A dynamic homeostasis between gut microbiome and the host is essential for animals. Antibiotics feeding may be a good way to study the function of microbes in insects due to efficiency and a linkage with pest control. Here, by using 16S rDNA sequencing, we show antibiotics feeding significantly altered the composition and diversity of microbes in different stages of Spodoptera frugiperda and showed dose dependent effects. Antibiotics ingestion resulted in a dramatic reduction of Enterococcus in larvae and Klebsiella in adults, but increase of Weissella in larvae and Pseudomonas in pupae and adults. Enterococcus spp in the lepidopteran gut may play a protective role against insect pathogens and Klebsiella spp may have positive effects on insect fecundity. Some strains from Pseudomonas and Weissella are pathogens or opportunistic pathogens. Further biological assay showed that antibiotics treatment significantly affected the fitness of treated insects and their untreated offspring, with treated insects and their offspring having longer developmental period but lower body weight, survival rate, flight capacity and fecundity than those of controls. Lepidopterans may rely on gut microbiome for some digestions and previous study indicated that antibiotics-induced dysbiosis of gut microbes affects many biological processes of S. frugiperda. Therefore, it is possible that antibiotics disrupted the homeostasis of gut microbes and the host, which then negatively affected the survival and reproduction of S. frugiperda. These findings contribute to a better understanding of the role of the microbiota in insects and will aid in the development of environmentally friendly management techniques for this pest.