The ant Lasius niger shows no relationship between task efficiency and body size variation among workers

Abstract

In ants, workers of different sizes may perform various tasks, even in so‐called monomorphic species with relatively low body size variation. However, it is unclear if the body size diversity of monomorphic workers correlates with task efficiency, especially in stressful contingencies. Here we tested if the body size variation of workers corresponds with its efficiency in transferring pupae. Transferring brood is a pre‐set behavioral response to stress, e.g. suboptimal temperature. Here we applied a laboratory experiment simulating nest damage. The study was performed on the common garden ant (Lasius niger (Linnaeus, 1758)) – a species with no distinct worker subcastes. The efficiency of workers was measured as the latency of transferring pupae from a lit part of the experimental colony to a darkened part, while the body size diversity was expressed as the within‐colony coefficient of variation in head width. We did not find any significant correlation between efficiency and body size variation. Summarizing the existing studies and the present results, we propose the hypothesis that the body size diversity of L. niger may have implications for workers’ division of labor but not for their task efficiency in a stressful contingency.

Behavioural changes in the city: The common black garden ant defends aphids more aggressively in urban environments

“…The thriving of L. niger in urban settings may be attributed to its behavioural plasticity, allowing it to perform various tasks – a trait well‐documented in this ant species. Lasius niger workers efficiently handle novel challenges, such as transferring brood in response to sudden nest disturbances (Okrutniak et al., 2023 ), and colonies demonstrate significant flexibility in reallocating labour, allowing them to quickly and effectively exploit newly available, high‐quality food sources (Bles et al., 2017 ). Furthermore, L. niger displays high behavioural adaptability to novel urban conditions, such as artificial light and increased night‐time temperatures, exhibiting enhanced nocturnal activity and prolonged foraging compared to rural populations (Trigos‐Peral et al., 2024 ).…”

Simulated biomechanical performance of morphologically disparate ant mandibles under bite loading

“…In addition to interspecific variation, mandible shape can vary intraspecifically between worker types in polymorphic ant species. In monomorphic ants, there is subtle morphological variation in the worker caste, mainly related to variation in body size 42 , 43 . In other cases, however, allometric scaling results in two or more recognizable discrete worker types (species often called dimorphic, trimorphic, and so on) or even continuous variation along a gradient, representing different levels of worker polymorphism 44 .…”