REPRODUCTIVE CASTE DETERMINATION IN EUSOCIAL WASPS (HYMENOPTERA, VESPIDAE)

Wasps (Vespidae) exhibit a range of social complexity, from solitary l iving to eusocial colonies, and thus are exemplary for studies of the evolutionary origin and maintenance of social behavior in animals. Int egral to the definition of eusociality is the presence of reproductive castes, group members that differ qualitatively in their ability to r eproduce in a social setting. Behavioral and morphological evidence su ggests that caste determination, the developmental process by which di fferences in fecundity are established, occurs to a large extent befor e adult emergence (pre-imaginally) in many species of Vespidae, in bot h basal and advanced taxa within the clade (Vespinae + Polistinae), wh ich includes most eusocial species. Pre-imaginal determination has bee n documented in many taxa (e.g. independent-founding Polistinae) where it was not thought to occur. Correlative and experimental studies ind icate that differences in nutrition during larval development are ofte n the basis of pre-imaginal caste determination pre-imaginal caste det ermination has important implications for the roles of subfertility an d manipulation by nest mates in the evolution of eusocial behavior.