Vitellogenin-like A–associated shifts in social cue responsiveness regulate behavioral task specialization in an ant

Abstract

Division of labor and task specialization explain the success of human and insect societies. Social insect colonies are characterized by division of labor, with workers specializing in brood care early and foraging later in life. Theory posits that this task switching requires shifts in responsiveness to task-related cues, yet experimental evidence is weak. Here, we show that a Vitellogenin (Vg) ortholog identified in an RNAseq study on the ant T. longispinosus is involved in this process: using phylogenetic analyses of Vg and Vg-like genes, we firstly show that this candidate gene does not cluster with the intensively studied honey bee Vg but falls into a separate Vg-like A cluster. Secondly, an experimental knockdown of Vg-like A in the fat body caused a reduction in brood care and an increase in nestmate care in young ant workers. Nestmate care is normally exhibited by older workers. We demonstrate experimentally that this task switch is at least partly based on Vg-like A–associated shifts in responsiveness from brood to worker cues. We thus reveal a novel mechanism leading to early behavioral maturation via changes in social cue responsiveness mediated by Vg-like A and associated pathways, which proximately play a role in regulating division of labor.

A small family business: synergistic and additive effects of the queen and the brood on worker reproduction in a primitively eusocial bee

“…2a). The additive interactions in our study were typical to behavioral changes 372 Kohlmeier et al, 2018). In the latter, vg was duplicated and its ortholog was associated with 373 behavioral maturation.…”

Abdominal microbial communities in ants depend on colony membership rather than caste and are linked to colony productivity

“…We assumed that individuals close to the brood were brood carers and those outside the nest were foragers. Assignment to worker caste based on a single observation is highly reliable in Temnothorax ants, including our focal species T. nylanderi (Beros, Enders, Menzel, & Foitzik, ; Kohlmeier, Feldmeyer, & Foitzik, ; Kohlmeier et al, ). The sampled workers were stored in clean 1.7 ml Eppendorf tubes at −20°C until DNA extraction.…”

Within-individual behavioural variability and division of labour in social insects

“…behaviours to compensate for the absence of larger and older workers (Crosland et al, 1997). In the ant Temnothorax longispinosus, old workers can revert to brood care after the removal of younger individuals, but young workers fail to accelerate their development to compensate for the removal of foragers (Kohlmeier et al, 2018). In honeybees, a reduction in the number of foragers induces precocious foraging in young bees, and nurse depletion triggers the behavioural reversion from foraging to brood tending, with the associated physiological changes (e.g.…”

“…The transition from nursing to foraging in honeybees correlates with an upregulation of the foraging gene (which codes for a protein kinase) that modulates phototaxis (Ben-Shahar et al, 2003) and gustatory responsiveness (Thamm and Scheiner, 2014). The transition to foraging has also been associated with downregulation of the vitellogenin gene (which codes for an egg yolk protein and modulates the response threshold for sucrose) in honeybees (Amdam et al, 2006) or a decrease in the responsiveness to cues emitted by brood in ants (Kohlmeier et al, 2018). A worker's behaviour can also depend on the acquisition or loss of physical abilities.…”