PARENT SESSION
Oral Session #23: Animal Ecology: Behavior and Sociobiology. Presiding: P. Brunkow.
Tuesday, August 7, 2001. 8:00 AM to 11:45 AM. Hall of Ideas E.
Variation in drinking performance among ants: effects on carbohydrate/protein availability and colony ergonomics.
Kay, Adam1, 1
ABSTRACT- The functional design of foragers may affect not only the quantity but also the nutritional composition of available resources. Because the plant and insect exudates collected by ants are rich in carbohydrates, colonies with workers that can collect liquid effectively may have greater access to carbohydrates relative to other nutrients. In the first part of this study, I compared drinking ability among workers of ten species - five that are known to collect exudates and five that are not. Mass-specific drinking rate differed over two orders of magnitude across species and was invariably and substantially higher in exudate feeders. Specific drinking rate was also positively correlated with a measure of carbohydrate:protein availability (determined previously), suggesting a causal link between drinking performance and nutrient availability ratios. In the second part of this study, I compared liquid loading capacity to worker size in seven species. Specific loading capacity was negatively correlated with worker size in three species (Dorymyrmex smithi, Formica perpilosa, and Pogonomyrmex occidentalis) and significantly increased with size in two others (Myrmecocystus mendax, Pheidole diversipilosa). The inconsistency of these patterns suggests that the colony-level advantage of performance differences varies among species. In F. perpilosa, workers foraging for nectar were significantly smaller than scavengers, suggesting that size-based differences in loading capacity increase foraging efficiency. These results indicate that measuring task performance can be an effective tool for understanding ant colony design.
KEY WORDS: ants, performance, drinking, division of labor