Abstract

Laboratory experiments showed that females Eogammarus oclairi molted during the night, mostly between 00:00-04:00 and were mated immediately. This molt synchrony may increase male-male competition for females, but it may also reduce the mortality of females from predation and cannibalism. When males were not present, females delayed molting for an average of 4 hours and did not ovulate. Both the mean proportion of females fertilized and fecundity rate (number of eggs per unit of female's weight) decreased as time in encountering a male increased. No female was fertilized when males were encountered 28 h after molting. These results suggest that molting behavior and physiological responses' of adult females increase their chances of successful reproduction. On the basis of the male's ability to mate more than one female in a short time, and the delay in the molting of females, we suggest that only a low proportion of females may lose a reproductive molt.