Recruitment and food-retrieving behavior in Novomessor (Formicidae, Hymenoptera)

Abstract

1. Novomessor cockerelli and N. albisetosus have been considered by previous authors to be individual foragers. This investigation, however, has demonstrated that workers of both species employ recruitment techniques when they encounter large prey. 2. Novomessor workers usually carry large food items in a cooperative action directly to the nest. 3. The chemical communication system employed during foraging was investigated in laboratory and field experiments. Secretions released from the poison gland proved to be the most effective recruitment signal. 4. In order to summon nestmates to large food objects, Novomessor employs the following two different recruitment techniques. Short-range recruitment: After discovering the prey, the scout releases poison gland secretion into the air. Nestmates already in the vicinity are attracted from as far away as 2 m and move upwind toward the prey. Long-range recruitment: If short-range recruitment does not attract enough foragers, a scout lays a chemical trail with poison gland secretion from the prey to the nest. Nestmates are stimulated by the pheromone alone to leave the nest and follow the trail toward the prey. 5. The trail pheromone is short-lived, and trail laying consequently does not lead to mass communication. Instead, the pheromone releases a short pulse of outrushing ants, usually numerous enough to subdue the prey and to carry it home when the ants act jointly. 6. In several field experiments, we demonstrated that these recruitment and prey-retrieving techniques enable Novomessor to counteract interference competition by mass-recruiting ant species.