EFFECT OF FEMALE MOLT STAGE AND SEX-RATIO ION COURTSHIP BEHAVIOR OF THE BLUE-CRAB CALLINECTES-SAPIDUS

In many species, males and females actively participate in courtship, and the outcome of pre-mating interactions influences the mating succe ss of both sexes, Female blue crabs, Callinectes sapidus, mate soon af ter their final molt to maturity. thus female molt stage dictates the timing of mating. In a field experiment, we manipulated female molt st age and sex ratio to test their effects on the courtship behavior of b oth sexes. if female behavior influences the behavior and pairing succ ess of males, and if male courtship influences male pairing-success. E arly-molt-stage females avoided males during courtship, whereas late-m olt-stage females sought out males. As a result, males had to pursue a nd capture early-molt-stage females whereas males displayed to late-mo lt-stage females and more easily physically controlled them, Males som etimes abandoned late-molt-stage females. but this occurred more often when females were abundant. The rate at which females avoided males w as positively correlated with that of males abandoning females. and ma les that were unsuccessful at pairing met with higher rates of female resistance than successful males, suggesting that female behavior infl uences male pairing-success. Unlike unsuccessful males. successful mal es more often made the transition between display and maintaining phys ical control of the female. At high male sex ratios, males initiated c ourtship more readily: thus both sexual competition and female behavio r influence male courtship in this species.