| This investigation examines morphological, behavioral, and electrophysiological aspects of foraging in carpenter ants. Foragers exhibit discrimination, orientation, and fidelity to learned food cues. Chemically-mediated behaviors may involve the newly-described tarsal sensilla.; Camponotus floridanus and C. pennsylvanicus foragers discriminate between sucrose solutions tainted with various phytochemicals. Individuals sample multiple sources, and often favor resources containing moderate phytochemical concentrations to solutions devoid of such stimuli. Strong phagodeterrents include caffeine and oxalic acid. Bitter Apple TM and salicin deter feeding only at relatively high concentrations. Foragers become increasingly active upon discovery of 5--10mM sinigrin in combination with sucrose, but not without sucrose. Higher sinigrin concentrations are acceptable or mildly deterrent. Foragers accept or prefer inositol at or below 100mM in sucrose, and usually prefer higher concentrations.; Field studies confirm that C. pennsylvanicus foragers learn and remember chemical cues associated with food. In two-choice tests, experienced ants orient selectively to learned cues in the absence of food. Naive ants prefer orange to basil, but feeding experience with basil reverses this preference. Trained ants generally switch preferences within 24 hours of training to a new food. Ants trained to basil, however, retain a preference for it even after three days of experience with orange, Possible mechanisms, implications of rapid associative learning, fidelity to whole-plant cues, and foraging strategy are discussed in terms of proximal colony fitness.; Tarsal sensilla are described for the first time from ants and from additional representative hymenopterans. Long, socketed sensilla chaetica (SC) are scattered across the cuticular surface. Minute, dorsolateral sensilla basiconica (SB) occur as distal transverse pairs on all tarsomeres. These sensilla occur on workers of the ant subfamilies Formicinae, Ponerinae, and Myrmicinae. Proposed homologous sensilla occur in representatives of eight additional aculeate families.; Morphological, histological, and electrophysiological evidence suggests contact chemosensory functions for the SB and mechanosensitivity of both the SB and the SC. Electrophysiological and overt behavioral evidence suggests thermosensitivity of the tarsal sensilla. No evidence has been found for olfaction or for anemotropism. The potential adaptive significance of tarsal sensilla is discussed. The SB are discussed with respect to the hypothetical ubiquity of contact chemoreceptors on insect appendages. |
