Abstract: 【Aim】 This study aims to clarify the circadian rhythms of the behavioural activities of Bradysia cellarum adults, and provide basis for indoor breeding, behavioral research and development of accurate and efficient monitoring and novel control technologies. 【Methods】 The circadian rhythms of courtship, mating, oviposition, movement and resting of B. cellarum adults during the emergence peak were observed and recorded, and the time allocation characteristics of their specific behavior were analyzed. 【Results】 The locomotor and resting behaviors of B. cellarum adults occurred both in the daytime and at night, and the frequencies of reproductive behaviors (courtship, mating and oviposition) occurring at night were higher than those in the daytime, and there were significant differences in the proportion of frequencies among movement, resting and reproductive behaviors at various time points. The female and male adults of B. cellarum showed the same courtship rhythm, with two courtship peaks at 3:00 and 7:00, respectively. The mating rhythms of female and male adults of B. cellarum were similar to the oviposition rhythm of female adults, and the proportion of frequencies of movement reached the peak at 3:00 while that of female adults reached the peak at 19:00. There was no obvious circadian rhythm peak in the proportion of frequencies of resting behavior of female and male adults. As for daily time allocation, the resting behaviors of female and male adults accounted for the largest proportion of time, with the proportions of time of females and males of 89.53% and 89.90%, respectively, and the proportions of time of courtship behaviors of female and male adults were the least, being 0.56% and 0.89%, respectively. There was no significant difference in the daily proportion of time of various behaviors between female and male adults. 【Conclusion】 The courtship, mating, oviposition, movement, and resting behaviors of B. cellarum adults show obvious circadian rhythms, and the frequency of occurrence of different behaviors and the time points of activity peaks are different.

Key words: Bradysia cellarum, circadian rhythm, courtship, mating, oviposition