Sperm displacement by two libellulid dragonflies with disparate copulation durations (Anisoptera)

The possibility that dragonflies with frequent, brief copulations differ from those with less frequent, longer copulations in the degree of sperm precedence by the last male to mate or in the mechanism by which sperm precedence is attained is examined.The reproductive behavior, sperm displacement ability and genitalic morphology of Celithemis elisa and Erythemis (Lepthemis) simplicicollis were studied, Celithemis have infrequent copulations of about 5 min in duration and oviposition is in tandem, while in Erythemis copulation durations last about 20 sec, males mate more frequently and mates are guarded for shorter periods of time. Both spp. are primarily sperm removers, despite their differences in copulation duration and penis morphology. In C. elisa about 68% of the sperm in a female’s bursa belongs to the last of 2 or more males to mate with her. For E. simplicicollis 54% of the sperm in the bursa belongs to the last male. Estimates of volume displacement for £ simplicicollis agree closely with data on sperm precedence for the same sp. (cf. M.E. McVEY & B.J. SMITTLE, 1984, J. Insect Physiol. 30: 619-628).