You smell different! Temperature interferes with intracolonial recognition in Odontomachus brunneus

Abstract

Intracolonial recognition among social insects is performed mainly by means of cuticular hydrocarbons (CHCs) that provide chemical communication, although their primary function is the avoidance of desiccation. Therefore, the ability to adjust to climatic variation may be related to the composition of CHCs. The hypothesis adopted in this work was that workers of the ant Odontomachus brunneus, when exposed to higher or lower average temperatures, change the CHCs composition, as a readjustment to the new conditions, and that this, in turn, leads to a change in intraspecific recognition capacity. To test this hypothesis, colonies of O. brunneus reared in the laboratory were subdivided into four groups. Two groups were kept at the same temperature, in order to assess the effect of isolation itself, while one group was kept at high temperature and another was kept at low temperature. Two groups were maintained at 25 °C, with no further conditions imposed. Subsequently, encounters were induced between individuals from these groups and from the high and low temperature groups, followed by the extraction of CHCs from each individual. The results indicated significant differences in recognition time and CHC composition between the high/low temperature groups and those kept at 25 °C. Antennation time during nestmate encounters was significantly longer for the groups submitted to temperature treatments (high and low), compared to those kept at 25 °C, suggesting recognition difficulty. In order to adjust to changing temperature conditions, O. brunneus undergoes changes in the composition of CHCs and in intraspecific recognition capacity.