Ant circadian activity associated with brood care type

Abstract

In group-living animals, social interactions influence various traits including circadian activity. Maternal care, in particular, can have a strong effect on the circadian activity of parents or nurses across taxa. In social insects, nestmates are known to have diverse activity rhythms; however, what kind of social environment is crucial in shaping an individual's rhythm is largely unknown. Here, we show that the focal brood types being taken care of (i.e. egg, larva and pupa) have significant effects on individual activity/ rest rhythm, using the monomorphic ant Diacamma ( putative species indicum). When isolated from a colony, nurses exhibited a clear circadian rhythm. However, when paired with eggs or larvae, they exhibited around-the-clock activity with no apparent rhythm. In contrast, a clear activity rhythm emerged when nurses were paired with a pupa, requiring little care. Such brood-type-specific changes in circadian activity are considered to arise from the difference in caretaking demands. Our finding may contribute to the understanding of the organization of a colony in the context of behavioural variability under different microenvironments.

A Role of Histone Acetylation in the Regulation of Circadian Rhythm in Ants

“…A possible explanation put forward was that larvae need care around-theclock, whereas foraging efficiency varies depending on the time of the day. This hypothesis was supported by the finding that experimental addition of brood to rhythmic individuals dramatically decreases the strength of their rhythm in Diacamma ants (Fujioka et al, 2017; but see Fuchikawa et al, 2014), bumblebees (Eban-Rothschild et al, 2011), and honeybees (Shemesh et al, 2010). One specificity of our study is that we recorded any type of activity inside the nest that was not limited to nursing behavior.…”

“…This situation is not unnatural for Temnothorax ants (Foitzik et al, 2004), as they inhabit small ephemeral nest sites such as acorns, where light shines in through the nest entrance. In addition, previous studies that reported an absence of rhythm for ant nurse workers also provided them with access to light (Fujioka et al, 2017;Mildner and Roces, 2017;Sharma et al, 2004). However, bee nurses show stronger synchronization when exposed to a light:dark regime (Fuchikawa et al, 2016;Shemesh et al, 2007Shemesh et al, , 2010, which could facilitate the detection of group-level rhythmicity.…”

“…Ant and bee workers that forage for food typically show rhythmic activity, whereas workers that nurse the brood inside the nest are often arrhythmic, fulfilling their social tasks around the clock (Fujioka et al, 2017;Ingram et al, 2009;Mildner and Roces, 2017;Moore et al, 1998;Sharma et al, 2004;Shemesh et al, 2010Shemesh et al, , 2007; but see Fuchikawa et al, 2014). Previous studies revealed that the presence of brood reduces circadian fluctuations in the activity of honeybee and ant nurse workers (Fujioka et al, 2017;Shemesh et al, 2010) and bumblebee founding queens (Eban-Rothschild et al, 2011), possibly because larvae need constant care. This indicates that the social environment affects circadian rhythms in social Hymenoptera (Fujioka et al, 2019).…”

Observation of plugging behaviour reveals entrance‐guarding schedule of morphologically specialized caste in Colobopsis nipponicus

“…For example, honey bee foragers are active during the daytime, namely flowering time, so that they can collect nectar and pollen (Bloch, Bar-Shai, Cytter, & Green, 2017). In contrast, nurse ants and bees are active all day long inside the nests because around-the-clock, brood care is considered necessary (Fujioka et al, 2017;Moore, Angel, Cheeseman, Fahrbach, & Robinson, 1998). In contrast, nurse ants and bees are active all day long inside the nests because around-the-clock, brood care is considered necessary (Fujioka et al, 2017;Moore, Angel, Cheeseman, Fahrbach, & Robinson, 1998).…”

“…Likewise, ant foragers exhibit circadian activity rhythms, that is, they have a periodic activity of approximately 24 hr: some species are diurnal and others are nocturnal (Lewis, Pollard, & Dibley, 1974;. In contrast, nurse ants and bees are active all day long inside the nests because around-the-clock, brood care is considered necessary (Fujioka et al, 2017;Moore, Angel, Cheeseman, Fahrbach, & Robinson, 1998). Thus, the time schedules of tasks are expected to depend on characteristics of the tasks.…”