ECDYSTEROIDS AND JUVENOIDS IN 2 MALE MORPHOTYPES OF LIBINIA-EMARGINATA

Two forms of the large-clawed male spider crab, Libinia emarginata, fr om the same molt stage, were examined to determine possible roles of e cdysteroids and juvenoids (methyl farnesoate) during maturation of the reproductive system and mating behavior. These forms are distinguishe d by the condition of the epicuticle covering the exoskeleton, abraded (worn away) and unabraded (intact), and mating behavior, active and i nactive, respectively. Methyl farnesoate (MF) levels in the blood are high during active reproduction (abraded males)-mating, mate guarding and male competition; but, when the animals are in reproductive diapau se (unabraded males), these levels are low. Ecdysteroids are found pri marily in the testes of both male types. However, the amounts detected are highest in the non-reproductive unabraded males, and lowest in th e actively mating abraded ones. It appears that ecdysteroids may funct ion early in maturation in unabraded animals by making the gonad compe tent, while MF may be functioning in mature males with developed repro ductive systems and exhibiting mating behavior.