Circadian mating rhythms, mating frequency, mating duration, and the effect of mating duration on fecundity and fertility in the cabbage beetle, Colaphellus bowringi were investigated in the laboratory. Mating occurred throughout the 24-h cycle but the majority of copulations occurred in the photophase with two apparent peaks, one at 8：00 and another at 16：00. Mating frequency observations for 10 consecutive days indicated that pre-mating period of C. bowringi was about 4 days, and pairs mated an average of 5 times per day and an average of 40 times during the first 10 days. There was a negative correlation between mating frequency and mating duration during the consecutive mating. The mean duration of the first copulation （136.24± 4.62 min） was significantly longer than those of the second （57.87 ± 2.03 min）, third （53.05 ±2.05 min） and fourth copulation （30.86 ± 2.98 min）. Fecundity showed a slight increase with increasing mating duration but no significant difference among treatments. However, fertility was significantly influenced by the mating duration in this species. Mating of 20-min duration did not produce viable eggs. The mean percentage of fertile eggs with completed mating duration （204.43±18.96 min, 56.75% fertile eggs） was significantly higher than those with 60 min （39.55%） and 30 min （17.91%） mating duration, suggesting that the longer mating duration might be associated with transfer of more sperm that are used to increase the fertility of eggs.
Xing-Ping Liu Hai-Min He Xian-Ju Kuang Fang-Sen Xue
