Nest architecture of group-living wasps <i>Microstigmus</i> (Hymenoptera: Sphecidae): role of the pedicel as a defense against ants

The nest pedicel of a social sphecid wasp Microstigmus nr. thripoctenuslplays an important role in protecting the brood against ant predators, as inferred froqi data on artificial nests.. A pair of artificial nests with or without pedicels was suspended Cromihe undersides of leaves ( Carludovica palmata ) for 30 rnin to assess rates of discovery and removal of food (tuna bait) by ants (N = 36 pairs). Three-hundred lmd forty-thlee individuals of five ant species removed food at a higher frequency from nests wihout pedicels (83.3% oC 36 nests) than from nests with pedicels (11.1 % of 36 nests).