The influence of age and development temperature on the temperature-related foraging risk of Formica cinerea ants

Abstract

Abstract Climate change and the subsequent increase of global temperature are the most current and important threats to biodiversity. Despite the importance of temperature, our knowledge about the level of behavioural and physiological adaptations of ant species from temperate regions to cope with high temperatures is limited compared to the broad knowledge of typical thermal specialists from warmer regions. In the current study, we investigated the temperature-related foraging risk of xerothermic ant species from the temperate climate in Europe, Formica cinerea. Our aims were to check how an increase in external soil temperature affects the foraging activity of workers and how the temperature during development and worker age affects foraging activity in high temperatures. Based on our results, we can draw the following conclusions: (1) the majority of workers utilize a risk-aversive strategy in relation to foraging in high surface temperatures; (2) pupal development temperature affects the risk taken by adult workers: workers that developed in a higher temperature forage more often but for shorter intervals compared to workers that developed in a lower temperature; (3) age is an important factor in temperature-related foraging activity, as with increasing age, workers forage significantly longer at the highest temperatures. Our study is one of the first to assess the potential factors that can affect the foraging risk of ants from a temperate climate in high ambient temperatures. Significance statement Our study is the first direct test of workers' age and the development temperature of pupae on the thermal-related foraging strategy of adult F. cinerea workers. It shows that worker age and the development temperature of pupae interact to promote tolerance of thermal stress. We found that with increasing age, workers are prone to forage significantly longer at the highest and riskiest temperatures. Workers that developed in the high temperature (28°C) foraged more often but for shorter intervals compared to workers that developed in the lower temperature (20°C). Interestingly, the factor of age is more significant for ants that developed in the higher temperature of 28°C; the foraging time of these ants significantly increased with their age.