Abstract: 【Aim】 Gut microbes play very important roles in various life processes of host. This study aims to further clarify the mechanism of interaction between gut microbes and host by exploring the effects of three microbes, Lactobacillus plantarum, Acetobacter malorum, and Saccharomyces cerevisiae, on the foraging, oviposition and development of Drosophila melanogaster. 【Methods】 Attraction assays were performed to detect the attractiveness of L. plantarum, A. malorum or S. cerevisiae in the culture to the unmated and mated adults of D. melanogaster, and the attractiveness of the single microbe or the mixture of the two or three microbes to the non-virgin D. melanogaster. Oviposition assays were performed to detect the oviposition preference of non-virgin D. melanogaster to the single microbe or the mixture of the two or three microbes. The eggs of D. melanogaster were transferred to the media inoculated with L. plantarum, A. malorum and S. cerevisiae, respectively, and the normal medium (control), and the larval body weight was measured; meanwhile, the eggs of D. melanogaster were transferred to the media inoculated with live and inactivated single microbe of the three microbes, respectively, and the normal medium, and the number of pupae was counted to ascertain the effects of different microbes on the development of larvae of D. melanogaster. The relative expression levels of InR, a key gene of insulin signaling pathway, in D. melanogaster larvae raised in the media containing L. plantarum, A. malorum and S. cerevisiae, respectively, and the normal medium for 72 h were detected by qRT-PCR. 【Results】 A. malorum mainly affected the oviposition of D. melanogaster, while L. plantarum and S. cerevisiae could affect both its foraging and oviposition. Compared with single microbe, the mixture of the two or three microbes had stronger attractiveness to non-virgin D. melanogaster. The oviposition preference assays showed that L. plantarum, A. malorum, S. cerevisiae and the mixture of the two or three microbes had significant attractiveness to D. melanogaster for oviposition in the order of mixture>A. malorum>S. cerevisiae>L. plantarum. In addition, L. plantarum, A. malorum and S. cerevisiae could promote the development of D. melanogaster larvae. The live microbes accelerated the development of D. melanogaster from larvae to pupae in the early stage of inoculation, but the promotion effect of the inactivated microbes lagged behind. The expression level of InR in the larvae of D. melanogaster cultured on the medium inoculated with A. malorum decreased significantly as compared to that in the control, while those in the larvae cultured on the media inoculated with L. plantarum and S. cerevisiae, respectively, significantly increased. 【Conclusion】 A. malorum can induce D. melanogaster to lay eggs, and L. plantarum and S. cerevisiae are attractive to D. melanogaster for foraging and oviposition. Meanwhile, microbial diversity can increase the foraging and oviposition preference of D. melanogaster. L. plantarum, A. malorum and S. cerevisiae may affect the growth and development of D. melanogaster larvae via different regulatory mechanisms.

Key words: Drosophila melanogaster, gut microbes, Lactobacillus plantarum; Acetobacter malorum, Saccharomyces cerevisiae, attractiveness, oviposition