Recruitment behavior, orientation, and the organization of foraging in the carpenter ant Camponotus pennsylvanicus degeer (Hymenoptera: Formicidae)

Abstract

1. The recruitment process of Camponotus pennsylvanicus initiates and regulates foraging activities. Scout ants recruit nestmates to new food sources with alerting motor displays. Workers subsequently leave the nest and follow a recruitment trail that appears to be composed of hindgut material and poison gland secretion (formic acid) to the food. Hindgut material functions as a long-lasting olfactory orientation cue between the food source and the nest, whereas poison gland secretion makes the recruitment trail highly attractive to stimulated ants. Hindgut trails may also have a recruitment effect. 2. Although hindgut material is an important orientation cue during foraging, because ants make repeated foraging runs they may also make use of visual cues. 3. Mass foraging is organized by the behavioral activities of recruiting ants. Starvation intensifies the recruitment displays of scouts, which releases a strong recruitment response in the colony. The behavior of individual recruiters during the organization of foraging facilitates at first a quick mobilization of nestmates to the food; subsequently recruiter behavior changes. These changes the facilitate food transport to the colony. The amount of food brought into the colony along with the decrease in recruitment behaviors may account for the waning and eventual termination of foraging activity. Only ants of a particular age bracket respond to recruitment signals and participate in foraging, and of this group only a small proportion of workers are consistently active in foraging. 4. When compared to other formicine species, the recruitment behavior of Camponotus pennsylvanicus appears to illustrate some features of chemical mass communication while still retaining characteristics of the group recruitment technique.