MATE GUARDING AND MATE CHOICE IN 2 COPEPODS, LERNAEOCERA-BRANCHIALIS (L) (PENNELLIDAE) AND LEPEOPHTHEIRUS-PECTORALIS (MULLER) (CALIGIDAE), PARASITIC ON FLOUNDER

Males of Lernaeocera branchialis (L.) establish precopula with conspecific mates of all parasitic developmental stages, but seem to prefer mature females or females close to maturation. However, male L. branchialis discriminate against females already inseminated once. They also prefer copepodites as mates to chalimus IV females already occupied by other males. In L. branchialis, sex-specific signals seem to develop during the copepodite and chalimus I stage, and the sexual signals seem to increase in strength or quality as the female larvae develop. In males, however, sexual signals probably remain unchanged after the chalimus I stage. This may account for the typical gregarious behavior of adult males. In contrast to males of L. branchialis, males of Lepeophtheirus pectoralis (Muller) establish precopula with postchalimus larvae only. Males of both species are, however, probably selected to minimize the time invested in each female. Thus, males of L. pectoralis preferentially choose recently matured females. Males of L. pectoralis seem to be reluctant to recopulate with a female if other categories of mates are present on the host, and the males also discriminate against older virgin females with an expanded genital complex. This suggests that the size (or shape) of the genital complex in L. pectoralis is important for recognizing the female state, whereas the size (or shape) of the cephalothorax seems to be of less importance, since males do not discriminate between preadult I and preadult II females.