Ambush predation by the neotropical ant Ectatomma ruidum (Hymenoptera, Formicidae, Ponerinae).

An ambush predation is individually used by hunters of the ponerine ant Ectatomma ruidum to capture halictid bees (Lasioglossum umbripenne) in the Panamanian mountains. Workers which use this strategy and originate from a colony A situated within a nest aggregation of halicitid bees, capture four times more prey than workers from a colony B with a foraging area which does not include this type of nests. Up to 48% of prey of colony A are halictid bees, demonstrating the local importance of this predatory strategy in E. ruidum, which is usually more eclectic in its diet. A close examination of the behavioral sequence of predation shows that amb;sh is successful in only 4.8% of cases (i.e. in 76 cases of 1591), a very low success rate in comparison to other predatory strategies described in this species. Nevertheless, due to the high repetition (16.1 +/- 5.9 times on average) of very short waiting phases, the real success rare (i.e. according to the number of individual trips) can reach up to 80%. A review of ambush predation among ant species allowed to distinguish approaches before jumping, long stealth approaches and real ambushes. Implications of learning and "expectation" processes are also discussed.