Sucrose acceptance threshold: a way to measure sugar perception in ants

Variation in the perception of sweet taste is a well-known phenomenon in the animal kingdom. Well-established protocols for measuring sucrose responsiveness in non-social insects and honeybees have made it possible to understand many aspects of their biology and behaviour. Ants are also advanced social insects that present a plethora of life histories with diverse strategies and behaviours; however, a universal paradigm possible to measure this response in different ant species has not yet been developed. Here, we present a protocol for measuring the sucrose acceptance threshold (SAT) under controlled conditions in harnessed ants with different feeding habits. By testing the response to antennal and palp sucrose stimulation and using the occurrence of licking as the response, we developed a non-ambiguous evaluation that allowed easy detection of threshold changes. The results showed that the response to both antennal and palp stimulation varied widely among species. Some species licked in response to antennal stimulation while others did so in response to palp stimulation. Using the appropriate kind of stimulation, we tested the SAT protocol in ants of different genera and ants of the same species with different levels of sugar reserve. The differences detected in both cases imply that the protocol is appropriate for measuring and detecting variations in sugar perception in ants.