VENOM GLAND MORPHOLOGY IN PEPSIS-PALLIDOLIMBATA-PALLIDOLIMBATA AND BIOLOGICAL USE AND ACTIVITY OF PEPSIS VENOM

Spider wasps, i.e., the family Pompilidae, in general, and those belon ging to the genus Pepsis in particular, are acknowledged to possess ve noms that are algogenic to humans and thus have the parsimonious funct ions of causing paralysis and providing defense against predators. The morphological organization of the venom system and its complex convol uted gland closely resembles that in social members of the Vespidae. T hese features distinguish the venom glands of the Pompilidae from thos e of the sibling family Mutillidae as well as those of the family Sphe cidae, which lack convoluted glands. Although the venom glands in Peps is species are very similar in morphology to those of social vespids, the lethality of Pepsis venom to mammals is several times less than th at of the social common wasps. These findings suggest that in terms of the evolution of venom activity and the associated glandular structur es, there was apparently no need for social wasps to develop extra par ts of the venom system for producing toxic, lethal, or powerful algoge nic components. All of the glandular parts of the venom gland of socia l wasps were already present in pompilids (and eumenids) and, presumab ly, in their ancestors.