The effect of age on non-reproductive division of labour in the tropical primitively eusocial wasp, Ropalidia cyathiformis

Abstract

Division of labour among workers (non-reproductive division of labour), a characteristic feature of eusocial insects enables the efficient functioning of their colonies. In many advanced insect societies division of labour is based on age (age polyethism). Primitively eusocial insects however are believed to have a weak age polyethism. Here we investigated the role of age in non-reproductive division of labour in the tropical primitively eusocial wasp, Ropalidia cyathiformis and compared it with that in Ropalidia marginata, a congeneric species that exhibits relatively strong age polyethism. Age had a significant effect on the first performance of the four tasks studied; tasks were initiated in the sequence feed larva, build, bring food and bring building material. We measured task performance as the absolute frequency of tasks performed (FTP) and the probability of performing a task relative to other tasks (PTP) and age as absolute age in days since eclosion as well as relative age compared to nestmates. FTP varied significantly with both absolute and relative age, although absolute age explained more variance. PTP varied significantly with absolute age but not always with relative age. This is contrary to R. marginata, where more variation is explained by relative age than by absolute age. There was no trade-off between intranidal and extranidal tasks in R. cyathiformis unlike in R. marginata where the frequency of intranidal tasks decreased and that of extranidal tasks increased with age. We conclude that age polyethism is weak and less flexible in R. cyathiformis compared to that in R. marginata.

Dominance behaviour and division of labour in the tropical primitively eusocial wasp Ropalidia cyathiformis

“…This is in contrast to R. marginata where workers appear to regulate each other's foraging through dominance behaviour by a decentralized self-organized manner (Premnath et al 1995;Bruyndonckx et al 2006;Lamba et al 2007;Gadagkar 2019). The lack of decentralised work regulation and presence of self-regulated foraging in R. cyathiformis is consistent with the lack of clear division of labour between intranidal and extranidal tasks in this species (Unnikrishnan and Gadagkar 2020).…”

“…We have previously shown that queen succession is based more on dominance behaviour in R. cyathiformis (Unnikrishnan and Gadagkar 2017) while it is more based on age in R. marginata (Bang and Gadagkar 2012). Similarly, age polyethism is relatively weak and rigid in R. cyathiformis (Unnikrishnan and Gadagkar 2020) while it is better developed and more flexible in R. marginata (Naug and Gadagkar 1998). Such comparisons between R. cyathiformis and R. marginata reveal that R. cyathiformis promises to be an ideal model system to understand the mechanisms of social organization and division of labour in typical primitively eusocial species.…”

“…Hence our sample sizes for the comparison of the behaviour of wasps between the queen-right and queen less colonies would be 19 nests and for all other comparisons it would be 23 nests. Data from the first set of 19 nests were also used to study queen succession (Unnikrishnan and Gadagkar 2017) and data from the second set of 4 nests were also used to study age polyethism (Unnikrishnan and Gadagkar 2020). Data from all the 23 nests are being used here to study the role of dominance behaviour in division of labour.…”

A Partition Theorem for a Randomly Selected Large Population

“…Cases of a given large population or subpopulation showing oscillatory behaviour of transitioning from a stationary to a non-stationary state or vice versa were earlier given in Rao and Carey (2019). The theory and partition methods described could be used in insect demography (Unnikrishnan and Gadagkar 2020;Chi et al 2019;Tasnin et al 2021), plant sciences (Mohammadi-Tabar et al 2015;Chalmandrier et al 2021), or other research areas where age-and aging-based stratification is done, for example Mondal et al (2016), Ning et al (2017) and Srivastava et al (2021). With many countries in the world approaching or at replacement levels but often with widely varying if not unstable age distributions, the partitioning theory outlined here has the potential to provide new metrics on age structure in particular, and on overall population dynamics in general.…”

A multi-scale review of the dynamics of collective behaviour: from rapid responses to ontogeny and evolution

“…The workers in colonies of many social insects shift from tasks within the nest when young, such as caring for brood, to riskier tasks such as foraging as they age, a phenomenon known as age (or temporal) polyethism [ 117 ]. Age polyethism is typically more pronounced in species with more advanced eusociality in contrast with those that are primitively eusocial [ 118 ], suggesting that it contributes to the success of eusociality, a highly advanced collective behaviour. The social environment can, however, influence the age that individuals change tasks in some species [ 119 ].…”