Abstract: 【Aim】 To explore the circadian rhythms of the synthesis and release of sex heromones Z11-16∶Ac and Z11-16∶OH and the calling and mating behaviors of adult Sesamia inferens, and their relationships with sex pheromone trapping in the field. 【Methods】 The sex pheromone titers of Z11-16∶Ac and Z11-16∶OH of female moths of S. inferens were analyzed by solvent extraction and solid phase microextraction (SPME), and the circadian rhythms of sex pheromone biosynthesis and release and the calling and mating behaviours of moths were investigated by behavioral observation and real-time counting of moth catches by sex pheromone trapping in the field in multiple localities. 【Results】 The detectable time of sex pheromone Z11-16∶Ac and Z11-16∶OH in the pheromone glands of female moths of S. inferens started at 1 h before scotophase, and increased rapidly at 4 h into scotophase, reaching the first peak at 8 h into scotophase and the 2nd peak at 1 h into photophase. The sex pheromone compounds were significantly detected at 5 h into photophase. The detectable time for sex pheromone compounds emitted outside of the glands started at 6 h into scotophase and peaked at 10 h into scotophase, and the sex pheromone Z11-16∶Ac titer still remained 96.9±20.9 ng/female even at 1 h into photophase. The ratios of Z11-16∶Ac and Z11-16∶OH obtained by solvent extraction were not significantly different in scotophase and photophase, with averages of 2.8±1.9 and 2.5±0.9, respectively, while the difference in the ratios of Z11-16∶Ac and Z11-16∶OH obtained by SPME was statistically significant in scotophase and photophase, with averages of 8.5±1.2 and 5.7±0.6, respectively. The full extrusion of ovipositor occurred at 6-8 h after scotophase, and lasted 80.8±4.4 min on average. The mating of S. inferens occurred at 4-10 h into scotophase, and lasted 83.4±5.0 min on average. The real-time hourly and daily counting of moth catches in the field by automatic counting of pheromone trapping in the four provinces of Guangdong, Sichuan, Zhejiang and Jiangsu showed that the number of moths trapped was relatively concentrated in time in the overwintering generation, but was relatively scattered in the following generations. The circadian rhythms of male moth trapping in the field were affected by such factors as geographical environment, season and generation. 【Conclusion】 This study reveals that the circadian rhythms of mating and sex pheromone release of S. inferens are inconsistent and the mating time is in the earlier period after scotophase. The range of effective release time of sex pheromone of female moths is shorter than that of response time of male moths to sex pheromone. The extrusion of the ovipositor is associated with the elevated release rate and the disperse range of the sex pheromones released by female moths.

Key words: Sesamia inferens, calling behavior, mating behavior, sex pheromone, circadian rhythm