Abstract: 【Aim】 To examine the generality of existing Drosophila melanogaster axenic and gnotobiotic operation techniques for insects, and to explore the promoting effect of symbiotic bacteria on the growth and development of D. melanogaster and Hermetia illucens based on this technique. 【Methods】 The improved Walch-hypochlorous acid-ethanol axenic operation technique was used to verify the viability of this operation technique with the eggs of H. illucens, Ostrinia furnacalis and Mythimna separata, and to optimize the axenic operation technique on H. illucens. The LB solid medium was used to isolate the bacteria from the intestine of D. melanogaster. 16S rRNA gene sequencing was used to identify the intestinal bacteria of D. melanogaster. In vivo colonization and generation transfer experiments were carried out to examine the commensalism between the intestinal bacteria  of D. melanogaster and D. melanogaster. D. melanogaster- and H. illucens-associated models were established. The developmental duration and growth rate of D. melanogaster were recorded to assess the promoting effects of the intestinal bacteria of D. melanogaster on the growth of D. melanogaster and H. illucens. qRT-PCR was used to examine the expression levels of the ecdysone signaling pathway-associated genes (PTTH and E74B) in the 2nd and 3rd instar larvae of D. melanogaster. 【Results】 Compared to traditional axenic operation techniques, the improved axenic operation technique increased the efficiency of establishing the axenic insects. By optimizing axenic operation technique through changing the treatment time of hypochlorous acid, this technique was applicable to insect eggs with low viscosity and thicker egg shells. The intestinal bacterium isolated from D. melanogaster was identified as Rahnella bruchi which could stably colonize in the intestine of D. melanogaster and delivered to descendants. R. bruchi significantly shortened the developmental duration, and increased the emergence rate and growth rate of D. melanogaster. Intestinal symbiont R. bruchi significantly shortened the developmental duration of H. illucens. At the molecular level, R. brunch significantly increased the expression levels of PTTH and E74B in the 2nd and 3rd instar larvae of D. melanogaster. 【Conclusion】 The optimized axenic operation technique is relatively applicable for insect eggs with thick egg shells and low viscosity. R. bruchi is a beneficial commensal bacterium of D. melanogaster, which can causally promote the growth and development of D. melanogaster. R. bruchi can promote the growth and development of H. illucens.

Key words: Drosophila melanogaster, Hermetia illucens, axenic operation; Rahnella bruchi, symbiotic bacteria, growth and development