Starvation endurance in the ant Temnothorax nylanderi depends on group size, body size and access to larvae

Social interactions in animal groups can buffer environmental stress and may enhance survival under unfavourable conditions. In the present study, the impact on starvation endurance of social group, access to larvae and cold shock is studied in the ant Temnothorax nylanderi Förster. Resource sharing is expected to lead to grouped workers surviving longer than isolated ones. Access to larvae may increase longevity if larvae serve as food, or may interfere with survival if they induce caring behaviour in workers. Cold shock serves as a stress factor and a negative influence on survival is expected. The results show that isolated workers have a shorter lifespan than grouped workers, which in turn live for a shorter period than grouped workers with larvae. Beneficial 'group effects' contribute to group survival and the presence of larvae increases worker survival because the workers presumably feed on the larvae. Thus, improved starvation endurance may reflect an additional benefit of a social lifestyle. Moreover, variance in survival is lower for grouped workers than for isolated workers: group members not only demonstrate improved survival, but also smaller within-group differences. Although a negative influence on survival is the expected outcome, this type of thermal stress is found to have no direct impact on starvation endurance other than moderating the differences between isolated and grouped workers.