Abstract: 【Aim】 To investigate the courtship and mating behavior rhythm of the jackfruit borer, Glyphodes caesalis, so as to provide a theoretical basis for the extraction and identification of sex pheromones of this insect, the mechanism of hermaphroditic communication and the cluster trapping technology. 【Methods】 The sex ratio of female to male pupae of G. caesalis was counted, the adult eclosion rates of G. caesalis during the light and dark periods were determined and its courtship and mating behaviors were observed. Moreover, the effects of host (Artocarpus heterophyllus), day-old age of adults and dark period on the mating rate, mating duration and mating frequency of this insect were also determined by proportional pairing test. 【Results】 The average sex ratio of female to male pupae of G. caesalis was 1.06∶1, and the proportion of female pupae was significantly greater than that of male pupae. The peak of eclosion of G. caesalis adults was concentrated in the 2 h before and after the light-dark transition period. The mating of G. caesalis occurred only in the dark period and was facilitated by the presence of the host A. heterophyllus, with the mating rate of 93.33%±2.89% in the fruiting group, significantly higher than that in the fruitless group (71.67%±14.43%). The mating age of adults in the fruiting group and fruitless group ranged from 3-5-day-old and 3-7-day-old, respectively. The mating rate of the 3-day-old adults in the fruiting group was 53.33%±11.55%, which was significantly higher than that in the fruitless group (31.67%±5.77%), while the mating rate of adults in the fruiting and fruitless groups gradually decreased with the increasing of adult age. In the fruiting group, the mating period of adults was mainly concentrated between 0-2 h into the dark period, the peak of mating occurred at 0-0.5 h of the dark period, earlier than that in the fruitless group, and the mating rate was 36.67%±17.56%. However, in the fruitless group, the mating period of adults was mainly concentrated between 0-3.5 h into the dark period, the peak of mating occurred at 1.0-1.5 h of the dark period, and the mating rate was 16.67%±11.55%. The female adults of G. caesalis mated up to 2 times, and the male adults mated up to 4 times, but the proportion of mating female and male adults decreased with the increasing of the mating frequency. The earlier the first mating, the higher the probability of multiple mating. When the first mating of female and male adults occurred at the 3-day-old, they could mate 2 and 4 times, respectively. When the first mating of female and male adults occurred at the 5-day-old, the two sexes had no multiple mating behaviors. 【Conclusion】 G. caesalis can mate multiple times, and the host A. heterophyllus has a facilitating effect on the mating. The mating behavior of this insect is rhythmic, and only occurs in the dark period. The peak of mating occurs at the 3-4-day-old, mostly within 0-2 h of the dark period.

Key words: Glyphodes caesalis, sex ratio, eclosion, courtship behavior, mating