Lipid content influences division of labour in a clonal ant

Abstract

The fat body, a major metabolic hub in insects, is involved in many functions, e.g. energy storage, nutrient sensing and immune response. In social insects, fat appears to play an additional role in division of labour between egg layers and workers, which specialize in nonreproductive tasks inside and outside their nest. For instance, reproductives are more resistant to starvation, and changes in fat content have been associated with the transition from inside to outside work or reproductive activities. However, most studies have been correlative and we still need to unravel the causal interrelationships between fat content and division of both reproductive and nonreproductive labour. Clonal ants, e.g. Platythyrea punctata, are ideal models for studying task partitioning without confounding variation in genotype and morphology. In this study, we examined the range of variation and flexibility of fat content throughout the lifespan of workers, the threshold of corpulence associated with foraging or reproduction and whether low fat content is a cause rather than a consequence of the transition to foraging. We found that lipid stores change with division of labour from corpulent to lean and, in reverted nurses, back to corpulent. In addition, our data show the presence of fat content thresholds that trigger the onset of foraging or egg-laying behaviour. Our study supports the view that mechanisms that regulate reproduction and foraging in solitary insects, in particular the nutritional status of individuals, have been co-opted to regulate division of labour in colonies of social insects.

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

“…The costs of intranidal tasks might be lower in P. punctata than in bees, e.g., brood care activities are probably more limited. We have also shown that P. punctata foragers can revert to nursing, egg laying, and regain fat content (Bernadou et al 2015(Bernadou et al , 2020. This suggests that workers are more flexible (Bernadou et al 2015(Bernadou et al , 2020 and that preforaging senescence can be reverted and is limited in comparison to honey bee workers.…”

“…We have also shown that P. punctata foragers can revert to nursing, egg laying, and regain fat content (Bernadou et al 2015(Bernadou et al , 2020. This suggests that workers are more flexible (Bernadou et al 2015(Bernadou et al , 2020 and that preforaging senescence can be reverted and is limited in comparison to honey bee workers. For example, reverted nurses in the honey bee do not rebuild their lipid stores (Toth and Robinson 2005).…”

“…This might be due to the percentage of time workers spent outside the nest, i.e., while it continuously increased in the other two colonies, time spent outside stabilized over time in PR25. It is tempting to speculate that more time spent inside the nest reduced outdoor activities, increased fat content of workers and slowed down senescence (Bernadou et al 2015(Bernadou et al , 2020.…”

Recent Advancement in Atypical Lipomatous Tumor Research

“…Among them, subcutaneous fat is the major component in the subcutaneous layer and is mainly composed of adipocytes. Traditionally, subcutaneous fat plays a major role in energy reserve, thermoregulation, and relief of the pressure from outside of the human body [1,2]. In addition, recent studies identified that the fat layer plays an additive function such as antimicrobial actions [3].…”

The plasticity of lifespan in social insects

“…For individuals that do not reproduce, the onset of foraging often amounts to a death sentence. Leaving a natural nest to forage for food is certainly associated with a tremendous increase in external mortality, but foragers age rapidly also in the relatively safe environment of flight cages or laboratory nests [56,57]. While it is presently debated whether the residual life expectancy affects the start of foraging or vice versa (e.g.…”