Copulation duration and probability of insemination in Anthocoris whitei (Hemiptera : Anthocoridae) as a function of male body size

The influence of male and female body size on copulation duration and proba bility of insemination was determined for Anthocoris whitei Reuter allowed to mate at two temperatures. Copulation duration decreased significantly wi th increasing male length or increasing relative size (male length divided by female length). Female length had no effect on copulation duration. We i nterrupted copulation at 20 or 40 min at both 25 and 15 degreesC to determi ne the interacting effects of male size, temperature, and copulation durati on on probability of insemination. Insemination probabilities increased wit h increasing male size, increasing temperature, and increased duration of c opulation. Large males were more successful than small males at inseminatin g females at cool temperatures and for severely shortened copulations. Resu lts are consistent with the hypothesis that males of this species experienc e physical difficulties either in achieving intromission or in forcing sper m through the aedeagus, and that larger body size in males lessens these di fficulties.