Male mating success in a natural population of Ischnura elegans (Vander Linden) (Odonata: Coenagrionidae)

A natural population of I. elegans was studied by mark-recapture techniques in Rome (Italy) during 25 days in June-August 1994. We marked 1043 male and 957 female and recaptured one third of them. Recaptured males were similar to unrecaptured ones in age at marking, date of marking and body size. Recaptured females were similar to unrecaptured ones in age and size, but were marked earlier. 53% of mature recaptured males and 34% of females were never observed to mate. The maximum number of matings obtained by a male was 3, but 1 female mated 7 times. The best predictor of male lifetime mating success (LMS) was mature lifespan. Mated males were smaller than unmated ones but body length was not correlated with LMS. The probability that males marked in copula obtained a second copulation was 7% higher than for males marked alone. We conclude that I. elegans females are clearly not monogamous in central Italy.