Nest site selection by two polistine wasps: The influence of Acacia-Pseudomyrmex associations against predation by army ants (Hymenoptera)

Nest site selection by two neotropical polistine wasps, Parachartergus apic alis and Polybia rejecta was studied in Quintana Roo, Mexico, to assess whe ther they nest in association with arboreal ants that protect them against army ants. Pa. apicalis nest mostly on Acacia occupied by the ant Pseudomyr mex ferruginea or Ps. peperi while Po. rejecta nest on these Acacia or on o ther trees occupied by large colonies of dolichoderine ants of the genera A zteca and Dolichoderus; Intraspecific nesting associations (nests on the sa me tree), also a possible anti-predator strategy, concerned only 13 out of 129 Pa. apicalis nests, whereas nesting associations were frequent and inde pendent of the associated ant species in Po. rejecta and concerned 58 wasp nests out of 92 (significant difference with Pa. apicalis). Interspecific a ssociations between wasps occurred only twice. The trees supporting wasp ne sts were grouped. We then tested the reaction of columns of Eciton burchell i, the most frequent army ant species noted, when confronted with Ps. ferru ginea located on branches of Acacia. Army ants avoided Ps. ferruginea, perm itting us to verify that the association with Pseudomyrmex could provide th e wasp nests protection against army ants (as known for associations with a rboreal Dolichoderinae).