Abstract: 【Aim】This study aims to elucidate the circadian rhythms of the behavioral activities of Phyllotreta striolata adults and the staying positions at different time under different light intensities， so as to provide a basis for indoor breeding, behavioral research, and the development of innovative control technologies. 【Methods】The circadian rhythms of movement, mating, feeding and resting of P. striolata adults were observed and recorded under the artificial light-dark conditions (light intensity: 5 000 lx; photoperiod: 16L∶8D), the time allocation characteristics and staying positions of their specific behaviors were analyzed, and the differences in their behavior activities under three light intensities (500, 5 000 and 10 000 lx) were compared. 【Results】The most prevalent behavioral activity observed in P. striolata adults during day and night was resting, which peaked from 22:00 to 6:00. Feeding of P. striolata adults was only observed during daylight hours, from 8:00 to 18:00, with a peak at 8:00. Mating of P. striolata adults occurred exclusively at night, from 0:00 to 2:00. From 6:00 to 18:00, P. striolata adults demonstrated a preference for the backside and heart of leaves, as well as the sides of insect rearing cages, with the proportions of frequency staying on these positions significantly higher than those at night. The proportion of frequency of adults remaining in the soil or on the leaf surface at night was significantly higher than that at daytime. Light intensity was shown to significantly influence the behavioral activities of P. striolata adults. Under the light intensity of 500 lx, there was a significant reduction in the proportion of frequency of feeding behavior of P. striolata adults. However, when the light intensity increased to 5 000 lx and above, the proportion of frequency of the resting behavior of P. striolata adults was significantly reduced. Under the light intensity of 5 000 lx, feeding behavior of P. striolata adults was most prevalent, and compared to the light intensity of 10 000 lx, the light intensity of 5 000 lx caused a notable decrease in the proportion of frequency of movement behavior of P. striolata adults. Additionally, under the light intensity of 500 lx, the proportion of frequency of P. striolata adults remaining on the backside and heart of leaves was significantly less than those under the other two light intensities, whereas under the light intensity of 5 000 lx, P. striolata adults tended to prefer staying on the surface of leaves. 【Conclusion】The behaviors of P. striolata adults, including movement, feeding, mating and resting, as well as their staying positions, exhibit distinct circadian rhythms. The frequencies of different behaviors and time points of activity peaks differ, and various behavioral activities and staying positions are subject to the effects of light intensity.

Key words: Phyllotreta striolata, circadian rhythms, light intensity, behavior, staying position