Activity Patterns and Age-dependent Changes in Behavior in the Clonal Ant Platythyrea punctata

Abstract

Age-based polyethism, wherein young individuals perform tasks within the nest and later transition to outside activities, is common among many social insects. This division of labor ensures the safety of workers with longer residual lifespans, such as brood caring nurses, and exposes only old individuals to increased extrinsic mortality risks. It appears however, that lifespan in workers is also shaped by intrinsic factors, such as senescence. The transition from nurse to forager is accompanied by various physiological and behavioral changes and seems to represent a crucial step in determining the subsequent life history of the individual. Here we investigate the daily activity pattern and detailed division of labor in colonies of the clonal ant Platythyrea punctata to better understand the dynamics of age polyethism in this peculiar species. We found that P. punctata colonies were mostly active during the day. At night, few workers were observed out of their nests. Workers showed a decrease in brood care and aggressive behavior over time. With increasing age individuals spent more time outside the nest and were more frequently observed walking. However, the transition to outside tasks did not follow a consistent time pattern in all colonies. Workers transitioning at a younger age seemed to die earlier than workers that began to forage later in life.

Injury shortens life expectancy in ants and affects some risk-related decisions of workers

“…Indeed, young and fit workers choose tasks inside the nest and switch to foraging outside when they get older (Hölldobler and Wilson 1990 ). This is accompanied by many physiological changes, e.g., altered protein and hormone levels (Hartmann et al 2020 ). Behavioral variation can be observed even within groups of workers belonging to the same sub-caste, as in termites, in which older soldiers are more risk-prone than younger soldiers (Yanagihara et al 2018 , see also Moroń et al 2008 ).…”

Foraging valor linked with aggression: selection against completely abandoning aggression in the high‐elevation ant Tetramorium alpestre?

“…, 2015; Hartmann et al. , 2020). In contrast, the opposites may apply to population Kue: Workers are peaceful (earlier studies) (Krapf et al.…”

“…, 2012; Hartmann et al. , 2020). However, we do not expect an uneven distribution of polyethism stages to have an impact on behavioral differences because we likely collected and included workers with a large range of different behavior tasks (except for callow workers) in all behavioral experiments performed.…”

“…Another explanation for the behavioral differences between Kue and Pen could be the temporal polyethism of workers (i.e., workers conducting different tasks depending on their age). Li et al (2014) found that older workers have a higher foraging efficiency, will likely die sooner, and are more willing to take risks than younger workers (Moroń et al, 2012;Hartmann et al, 2020). However, we do not expect an uneven distribution of polyethism stages to have an impact on behavioral differences because we likely collected and included workers with a large range of different behavior tasks (except for callow workers) in all behavioral experiments performed.…”

“…data), bold, and forage more food (this study) but possibly have a lower life expectancy due to taking more risks. This, in turn, may negatively impact colony growth and reproduction in the long run (Sih et al, 2004;Modlmeier & Foitzik, 2011;Moroń et al, 2012;Jandt et al, 2014;Sih et al, 2015;Hartmann et al, 2020). In contrast, the opposites may apply to population Kue: Workers are peaceful (earlier studies) (Krapf et al, 2019;Krapf et al, unpubl.…”