Carbohydrate regulation in relation to colony growth in ants

Abstract

SUMMARYAnts and all social insects are faced with a nutritional challenge: the food entering the colony is brought by only a small number of its workers but is shared among all members of the colony. In this study, we investigated how ants maintain carbohydrates supply at both a collective and an individual level in response to changes in the concentration of available sucrose solution, colony demography and larval growth. We manipulated the concentration of sugar solutions available to ant colonies (dilute, medium and concentrated solutions) over extended periods and measured the capacity of colonies to maintain sugar supply through compensatory feeding. First, we demonstrated that ants regulated carbohydrate intake at a collective and individual level. Initially, ants consumed most and recruited fastest in response to more concentrated than to dilute sugar solutions, but over time this pattern reversed, such that the number of ants that fed and the volume ingested by each ant was a negative function of sugar concentration in the diet. Second, we found that ants became better at regulating their carbohydrate intake with the production of larvae in the nest. When the number of larvae was experimentally doubled, the ants regulated their consumption of carbohydrates more accurately than when the number of adult workers was doubled, suggesting that larvae play an important role in providing nutritional feedback to workers. Finally, we showed that ants defended a carbohydrate 'intake target' by allowing them to select among sugar solutions of different concentration.

Resistance to nutritional stress in ants: when being fat is advantageous

“…Carbohydrate scarcity in either the high-protein diet or highly diluted diet has been observed to trigger increased foraging activities in ants in order to achieve a target intake of carbohydrate (Dussutour and Simpson, 2008b, 2009Cook et al, 2010). However, this compensatory feeding behaviour does not occur immediately but is observed after a certain period of carbohydrate deprivation (Dussutour and Simpson, 2008b). In our experiment, foragers regulated carbohydrate intake after only a few days.…”

Nutrition and interference competition have interactive effects on the behavior and performance of Argentine ants

“…Recently, Dussutour and Simpson (2009) found a qualitatively similar result in a species of Rhytidoponera ants. By quantifying food intake, they showed that colonies on high P:C diets increased food gathering to maintain carbohydrate levels (see also Dussutour and Simpson 2008b), but greater food intake resulted in excess protein accumulation that was in turn associated with increased worker mortality. It remains unclear how high P:C diets increase mortality rates, although it could be related to costs associated with eliminating nitrogenous waste products (Lee et al 2008).…”

The nature of nutrition: a unifying framework

“…To answer this question, Dussutour and Simpson (2008) set about posing nutritional conundrums for an Australian species, the green-headed ant, Rhytidoponera metallica. Results indicated that ant colonies compensate over time by increasing their collection of dilute over concentrated sugar solutions.…”