Abstract: [Objective] Basilepta melanopus is a defoliator of Camellia oleifera in southern China. The sexual selection, mating, and fecundity of B. melanopus (Coleoptera:Chrysomelidae) were studied to determine the pest occurrence mechanisms. It may help in the development of sex pheromone used in trapping method for controlling the pest.[Method] Mature overwintered larvae were collected from the soil under the trees of Camellia oleifera in Yongan (Changsha, Hunan), and reared in the laboratory to obtain adults for this experiment. Mating pairs of newly eclosed adults were placed in a plastic box, where their mating behavior was observed (pre-copulation, copulation and post-copulation), along with the mating and oviposition circadian rhythms (counting the number of eggs laid and the matings during the day and at night). The influences on these behaviors of prior mating experience and long-term pairing were also explored.[Result]Adults of B. melanopus began to mate in 5-6 days after eclosion, and mated on average (5±4.2) times per day. Mating period lasted from 1-40 min, for an average of (18.9±9.3)min.In six to seven days after their last mating, females began to lay eggs, mean egg-production was (275.5±131.4). Mating behavior occurred most frequently at 10:00, accounting for about 40% of total mating,followed by at 16:00 and 18:00 and a low level mating was observed only at the rest time. Oviposition activity peaked two times at 16:00, 18:00, besides, at 14:00 and 22:00, to less at 2:00 oviposition also had smaller peaks. Females tended to choose smaller males to mate with, while males tended to mate with non-virgin females.[Conclusion] Female and male adults of B. melanopus mated multiple times, and both body size and mating experience of adults had significant effects on sexual selection.

Key words: Basilepta melanopus, sexual selection, mating behavior, fecundity behavior