Social organization and foraging success in Lasius neoniger (Hymenoptera: Formicidae): behavioral and ecological aspects of recruitment communication.

Live, moribund, or dead arthropods are gathered by Lasius neoniger through individual and social retrieval. 85% of the total biomass of prey (fresh weight) in the diet is cooperatively retrieved by groups of workers. Short-and long-range chemical recruitment signals coordinate cooperative foraging. Stort-range recruitment of workers to assist in the retrieval or defense of prey is achieved by simultaneous discharge of hindgut material and poison gland secretion. In long-range recruitment, workers discovering prey deposit a trail of hindgut material while returning to the nest. Hindgut pheromone both stimulates nestmates to leave the nest and orients them to the food source. Colony response is adjusted according to prey weight. Group retrieval of prey follows after a sufficient number of foragers have been recruited to move the prey. Rapid prey movement decreases the exposure of food sources to neighboring conspecific and interspecific competitors. The ability to move prey rapidly is limited to prey on the order of 130 mg or less in weight. The probability of interference during foraging and resource loss to competitors increases with increasing prey size, but the probability of loss is significantly less than the probability of interference for intermediate size prey (∼20 mg), which can be moved quickly. The foraging and recruitment behaviors of Lasius neoniger appear to have a prey size-dependent effectiveness which results in greater foraging success on prey of a relatively narrow size range above those prey that can be retrieved by solitary foragers.