Abstract: 【Aim】 To investigate the effects of lactic acid bacteria Weisellas paramesenteroides on the growth and development of Drosophila melanogaster. 【Methods】 Bacterium was isolated from the gut of D.melanogaster adults with selective medium and identified by BLAST analysis of 16S rRNA gene. The developmeantal duration of D. melanogaster was quantified by counting the time to puparium formation and adult eclosion, and the growth rate was calculated as the body surface area of larvae. The expression levels of genes involved in hormoral (dib, E74B and PTTH) and insulin signaling（DILP2, DILP3 and InR）of D. melanogaster at different time after egg deposition were assayed by quantitative real-time PCR. The glucose level in the hemolymph of the 3rd instar larvae was measured by glucose oxidase assay. 【Results】 W. paramesenteroides was isoloated and efficiently colonized in the gut of D. melanogaster adults. W. paramesenteroides shortened the time to puparium formation and adult eclosion of D. melanogaster by enhancing the growth rate of flies. W. paramesenteroides increased the expression levels of dib, E74B and PTTH, as well as the expression of DILP2 and DILP3, while decreased the expression levels of InR and the glucose level in larval hemolymph.【Conclusion】 W. paramesenteroides is the symbiotic bacterium of D. melanogaster, and promotes its development by activting the ecdysone and insulin signaling pathways.

Key words: Weissella paramesenteroides, Drosophila melanogaster, development, ecdysone signaling pathway, insulin signaling pathway