Expressions of conventional vitellogenin and vitellogenin‐like A in worker brains are associated with a nursing task in a ponerine ant

Abstract

In eusocial insect colonies, non‐reproductive workers often perform different tasks. Tasks of an individual worker are shifted depending on various factors, e.g., age and colony demography. Although a vitellogenin (Vg) gene play regulatory roles in both reproductive and non‐reproductive division of labours in a honeybee, it has been shown that the insect Vg underwent multiple gene duplications and sub‐functionalisation, especially in apical ant lineages. The regulatory roles of duplicated Vgs were suggested to change evolutionarily among ants, whereas such roles in phylogenetically basal ants remain unclear. Here, we examined the expression patterns of conventional Vg (CVg), Vg‐like A, Vg‐like B and Vg‐like C, as well as Vg receptor, during the task shift in an age‐dependent manner and under experimental manipulation of colony demography in a primitive ant Diacamma sp. Expressions of CVg and Vg‐like A in a brain were associated with a nursing task. It is suggested that associations of brain expressions of these Vgs with worker tasks were acquired in the basal ant lineage, and that such Vg functions could have sub‐functionalised in the derived ant lineage.

Individual experience influences reconstruction of division of labour under colony disturbance in a queenless ant species (Diacamma cf. indicum)

“…In D. cf. indicum, after reverted foragers have nursed for at least 7 days, they exhibit upregulation of both genes to the same level as original nurses (20). Therefore, we suggest that original nurses require more time for physiological modulation than original foragers, resulting in the differential impact of task experience.…”

“…Our ndings may indicate that task experience has a differential effect on the response threshold of original foragers versus original nurses. In general, the physiological states of workers are modulated to the speci c tasks (19)(20)(21)(22)(23)(48)(49)(50)(51)(52)(53). Additionally, some studies have evaluated physiological changes of workers that have been "respecialized" to a speci c task.…”

“…Physiological factors necessary to the performance of the tasks also alter depending on that task (19)(20)(21)(22)(23). Thus, worker behavioural exibility maintains robustness of DOL in insect societies.…”

“…However, the age structure of a colony also changes temporally, such as with the death of workers. Studies across several taxa have reported that workers shift exibly from their current tasks to the other tasks depending on social demands; for example, Page 3/18 foragers can shift back to the nurse role when the number of nurses is insu cient (8,(12)(13)(14)(15)(16)(17)(18).Physiological factors necessary to the performance of the tasks also alter depending on that task (19)(20)(21)(22)(23). Thus, worker behavioural exibility maintains robustness of DOL in insect societies.Individual experience, such as predator encounters and physical competitions, in uences behavioural variation (24-29).…”

Individual Ants Do Not Show Activity-Rest Rhythms in Nest Conditions

“…Monodomous nest habitats are open lands, such as grasslands at the forest edge (Fukumoto and Abe, 1983). This ant has been studied as a model system in various fields of study, including circadian rhythms (Fuchikawa et al, 2014; Miyazaki et al, 2020; Okada et al, 2017; Shimoji et al, 2020; Win et al, 2018). We also examined the effect of social interactions on activity-rest rhythms.…”