WHY DO MALE CRAB SPIDERS DRINK NECTAR

Misumenoides formosipes is a protandrous, semelparous crab spider comm on on flowers in North America. Females are 20-50 times heavier than m ales, which seldom feed on prey as adults, but search for and guard po tential mates. Nectivory, previously unproven for spiders, was observe d in male M. formosipes. Males were studied on Queen Anne's lace, Dauc us cai ota, to determine the importance of nectar as an energy and wat er source and its effect on male longevity. Because of their low mass and large surface-to-volume ratio males were more prone to dehydration than females. Drinking nectar replaced fluid that males lost through evaporation, although dew and rainwater were more efficient sources of fluid because the volume per nectary was very small. Males preferred drinking a simulated nectar source (30% sucrose solution) to water, an d even when satiated with water would still drink the sucrose solution , suggesting nectar was used as an energy source. Males offered nectar for an hour a day lived longer than males given only water. Nectar fe eding may have evolved because of the selective advantage of increased longevity for male reproductive success.