Abstract: 【Aim】 To study the oviposition selection of Drosophila in the presence of allicin, and to elucidate the underlying mechanism and biological significance of the oviposition avoidance of Drosophila. 【Methods】 The oviposition preference of female adults of Drosophila melanogaster to allicin at different concentrations (0.01%, 0.015% and 0.02%) was assayed by using the two-choice apparatus. The position effect of allicin on D. melanogaster was detected by oviposition apparatus. The feeding behavior of D. melanogaster was detected by capillary feeding method, and the sensory modality mediating this behavior was studied by using dark conditions, surgically removing forelegs, surgically removing antennae, and olfactory mutants. The effects of allicin on the developmental duration and survival rate of D. melanogaster offspring were investigated. The effects of 0.02%, 0.05% and 0.1% allicin on adult life span of D. melanogaster and the running speed and climbing speed of adult D. melanogaster after exposure to 0.1% allicin for 48 h were examined. The reactive oxygen species (ROS) level in intestine of D. melanogaster adults exposed to 0.02% allicin for 3 d was detected by using fluorescent dyes. 【Results】 Allicin caused oviposition avoidance in female adults of D. melanogaster. In response to 001%, 0.015% and 0.02% allicin, the oviposition indexes of female adults of D. melanogaster were -0.53, -0.77 and -0.88, respectively. D. melanogaster adults showed obvious location avoidance to allicin, with the position indexes of -0.09 and -0.22 to 0.01% and 0.015% allicin, respectively. In darkness and with foreleg removed, the female adults of D. melanogaster showed no significant oviposition avoidance to allicin. However, the female adults of D. melanogaster with antennae removed had significantly decreased oviposition avoidance to allicin, with the oviposition indexes of -0.01, -0.04 and -0.11 to 0.01%, 0.015% and 0.02% allicin, respectively. The oviposition avoidance of the mutant transient receptor potential ankyrin 1 (TrpA¹) to allicin disappeared, with the oviposition indexes of -0.09, -0.06 and 0.13 to 0.01%, 0.015% and 0.02% allicin, respectively. After the eggs laid by female adults of D. melanogaster were exposed to 0.02% allicin, the time to puparium formation and time to adult eclosion of offspring were prolonged by 1.85 and 1.88 d, and the pupal and adult survival rates were decreased by 26.01% and 31.28%, respectively. Allicin at the concentrations of 0.02%, 0.05% and 0.1% shortened the life span of adult D. melanogaster and the climbing speed of adults was significantly reduced by 0.1% allicin at 48 h after treatment. Treatment of 0.02% allicin for 3 d increased the ROS level in the intestine of adult D. melanogaster. 【Conclusion】 Allicin induces oviposition avoidance in adult D. melanogaster, which is mediated mainly by olfaction system, and causes midgut damage in adult, thus reducing the growth and development of offspring and the survival rate of adults.

Key words: Drosophila melanogaster; allicin, oviposition avoidance, olfactory system, developmental duration, survival rate