Caste Differences in Polybia emaciata, a Mud-Nesting Eusocial Wasp (Hymenoptera: Vespidae) that Bear on Pre-Imaginal Determination but not Size Differences

摘要

The Epiponini is a group of social wasps living in polygynic societies. The caste dimorphism Varies from incipient to well distinct. Morphometric analyses on twelve body parts and bvarian development of Polybia emaciata Lucas 1879, were used to estimate the level of caste differentiation in seven colonies. Physiologic differences were found. The queens the ovaries were inseminated and presented highly developed; in intermediaries as females, ovaries slightly developed and uninseminated, and for the workers the ovaries were not developed and inseminated. Besides, the coloration of the mesosoma and metasoma were darker in workers and intermediates. Morphometric analysis evidenced slight morphological differences. Even though body proportions were not enough to discriminate castes, the fifth sternite of the gaster had important characters that were able to differentiate queens from workers and intermediates. We propose that P. emaciata presents a case of pre-imaginal caste determination, which is not strictly based on size.