Prey capture behavior of Psalidomyrmex procerus (Formicidae : Ponerinae), a specialist predator of earthworms (Annelida)

Foraging workers of Psalidomyrmex procerus, which specialize in earthworm p redation, have a hunting behavior well adapted to this kind of prey. For a total of 106 tested earthworms, they captured entire individuals or a piece of prey in 105 cases from the first encounter (99.9%). Small earthworms we re detected by contact, long individuals from a distance. The seizure of sm all prey by their anterior section permitted the ants to capture them whole , after stinging limited prey movements. Long individuals were seized at an y point along their bodies and were not always stung. When seized by their anterior part these prey contracted their muscles and/or wiggled, triggerin g stinging. When seized by the middle or the distal part of their bodies, t he prey autotomized. Workers therefore obtained immobile pieces of prey and did not sting, As a result, the antipredator strategy of the earthworms is advantageous for both predator and prey: the ants easily retrieve prey pie ces, while autotomy permits the regeneration of the earthworms. These resul ts are discussed with reference to other predatory ants confronted with tub ular shaped prey, such as Tenebrio larvae, with large individuals being sei zed by the anterior part of their bodies and stung at this level, preventin g them from struggling.