Abstract: 【Aim】 To study the oviposition avoidance of Drosophila melanogaster to high salt, and to explore the biological significance of this phenomenon by the changes of the survival rate and developmental duration of the offspring under high salt. 【Methods】 The oviposition preference of female adults of D. melanogaster and D. yakuba to culture media containing 0.25 and 1 mol/L NaCl was assayed by the twochoice apparatus. The location effect of 1 mol/L NaCl on D. melanogaster adults was detected with oviposition apparatus. The oviposition ability of D. melanogaster adults under salt stress was detected with forced oviposition assay. The feeding behavior of D. melanogaster under salt stress was examined with capillary feeding and mouthpart extension assays. The visional and olfactory perceptions of oviposition selection were carried out in darkness and with Orco² mutant, respectively. The sensory system mediating this behavior was studied by surgically removing the partial taste receptor of D. melanogaster forelegs and using the saline taste mutant Ionotropic Receptor 76b (IR76b). D. melanogaster was cultured on the media containing a serial of concentrations of NaCl (0, 0.25, 0.50, 0.75 and 1 mol/L), and the effects of NaCl on the developmental duration and survival rate of the offspring of D. melanogaster were investigated. 【Results】 The female adults of D. melanogaster avoided to lay eggs on the media containing 0.25 and 1 mol/L NaCl, with the oviposition indexes of -0.45 and -0.59, respectively. D. yakuba adults created similar response to high salt, with the oviposition preference indexes of -0.78 and -0.99, respectively. Both species tested showed oviposition avoidance to high concentration of KCl and CaCl₂. D. melanogaster avoided to stay at the media containing 0.25 and 1 mol/L NaCl, with the location indexes of -0.74 and -0.88, respectively. There were comparable numbers of eggs laid on the media containing 0, 0.25 and 1 mol/L NaCl. D. melanogaster adults rejected 0.25 and 1 mol/L NaCl, with the feeding indexes of -0.37 and -0.41, respectively, and their appetite decreased as the concentration increased. Under darkness, D. melanogaster adults still showed a significant avoidance response to 0.25 and 1 mol/L NaCl, with the oviposition indexes of -0.49 and -0.59, respectively. After the forelegs of D. melanogaster adults were removed, the oviposition avoidance response of flies to 0.25 mol/L NaCl was impaired, with the oviposition index of -0.05. The oviposition avoidance response of IR76b mutant to 0.25 and 1 mol/L NaCl was compromised, with the oviposition indexes of 0.46 and 0.39, respectively. The time to puparium formation of the offspring on the media containing 0.25 mol/L NaCl was significantly prolonged by 0.40 d as compared to the control, and the larval survival rate of the offspring was decreased by 16.5%. The eggs of the offspring completely failed to form pupa and adults on the medium containing 1 mol/L NaCl. 【Conclusion】 Female adults of D. melanogaster display the oviposition avoidance to high salt through salt taste perception, thus promoting the development and larval survival of the offspring.

Key words: Drosophila melanogaster, high salt, oviposition avoidance, gustatory system, developmental duration, survival rate