Long live the wasp: adult longevity in captive colonies of the eusocial paper wasp Polistes canadensis (L.) (original) (raw)
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Cambridge University Press eBooks, 2017
The striking differences in lifespan observed among some social insect castes offer unique opportunities to study ageing and have therefore attracted increasing attention. While evolutionary theories of ageing can explain the long lifespan of social insect queens, experimental evidence to support them is lacking or contradictory. Furthermore, how social insects age is still poorly understood. Senescence patterns vary between behavioural worker castes and senescence in honeybee workers can even be reversed by inducing a caste transition, but explicit comparisons between queens and workers are needed to understand how queen longevity is linked to senescence. The ability of queens in advanced insect societies to combine long lifespans with high investment into reproduction presents a physiological puzzle, which may be solved in honeybees by the unique relationship between Juvenile Hormone and Vitellogenin. How this is achieved in other species remains unclear. We finish with a consideration of the challenges facing research into social insect ageing and discuss how these can best be met.
Long live the queen: studying aging in social insects
AGE, 2005
Aging is a fascinating, albeit controversial, chapter in biology. Few other subjects have elicited more than a century of ever-increasing scientific interest. In this review, we discuss studies on aging in social insects, a group of species that includes ants and termites, as well as certain bee and wasp species. One striking feature of social insects is the lifespan of queens (reproductive females), which can reach nearly 30 years in some ant species. This is over 100 times the average lifespan of solitary insects. Moreover, there is a tremendous variation in lifespan among castes, with queens living up to 500 times longer than males and 10 times longer than workers (non-reproductive individuals). This lifespan polymorphism has allowed researchers to test the evolutionary theory of aging and Y more recently Y to investigate the proximate causes of aging. The originality of these studies lies in their use of naturally evolved systems to address questions related to aging and lifespan determination that cannot be answered using the conventional model organisms.
Animal Behaviour, 1992
The relationships between foraging tenure and specialization on materials, and foraging tenure and foraging activity were measured for marked, known-age workers of the social wasp Polybia oeciden talis. The purpose of the study was to assess differences in cost to foragers, in terms of risk of mortality, associated with material specializations and activity level, and determine whether ontogenetic changes in forager behaviour reflect these differences in cost, such that more risky patterns of behaviour are postponed until later in adult life. Polybia occidentalis workers terminated foraging at an average of 5-9 days after their first trip, independent of their age at first foraging, suggesting that this task entailed a high risk of mortality. Lifetime foraging activity was calculated as foraging rate (mean number of trips per hour), foraging effort (mean number of time-weighted trips per hour), and as the proportion of observation days that an individual was active during her foraging tenure. Foraging tenure was not related to foraging rate or effort, but had a strong negative relationship with the proportion of observation days during which an individual foraged. By the latter measure, risk of mortality increased with foraging activity: The length of foraging tenure was negatively correlated with the proportion of foraging effort devoted to food materials (nectar and insect prey), supporting the hypothesis that gathering food was riskier than gathering nest materials (water and wood pulp). Foragers that switched between food and nest materials exhibited no tendency to specialize on nest materials first and therefore foraging for riskier materials was not always performed later in adult life. These results are discussed in terms of possible factors regulating task performances at the individual level in social insects.
Lifetime reproductive success and longevity of queens in an annual social insect
Journal of Evolutionary Biology, 2009
Although central to understanding life-history evolution, the relationship between lifetime reproductive success and longevity remains uncertain in many organisms. In social insects, no studies have reported estimates of queens' lifetime reproductive success and longevity within populations, despite the importance of understanding how sociality and associated within-group conflict affect life-history traits. To address this issue, we studied two samples of colonies of the annual bumblebee, Bombus terrestris audax, reared from wild-caught queens from a single population. In both samples, queens' lifetime reproductive success, measured as either queens' inclusive fitness or as total biomass of queen-produced sexuals (new queens and males), was significantly positively associated with queen longevity, measured from the day the first worker was produced. We suggest that a positive relationship between reproductive success and longevity was inherited from nonsocial ancestors showing parental care and maintained, at least in part, because the presence of workers buffers queens against extrinsic mortality.
Ageing Research Reviews, 2005
Life-history theory generally predicts that there should be no selection for longevity beyond the limit of reproductive capacity. However, the capacity to increase fitness may not end when individuals reach a state of functional sterility. Recent studies show that intergenerational transfers of resources from post-reproductive parents can increase the offspring's fitness, and analytical theory shows that age-trajectories of transfers may shape the course of senescence in social organisms. In eusocial insects, female roles are partitioned so that one phenotype or "caste" reproduces while another is responsible for resource transfers: the reproductive "queens" are arrested in a continuous reproductive mode, while transfer-activities such as hygienic behaviors, guarding, foraging and further food processing ("nursing") that increases the nutritional value of provisions are conducted by sterile "workers". Worker honey bees normally perform these tasks in a sequence so that nursing inside the protected nest is conducted prior to more risky exterior hive activities such as guarding and foraging. However, foragers may revert to nurse-activity in response to demographic changes, and worker bees can also develop into a stress resistant survival form with a 10-fold increase in lifespan. This elastic division of parental functions is believed to increase colony fitness. Further, it generates a stage-dependent trajectory of senescence that is difficult to address with established theories of aging. In the following, we show how a recent theory that includes resource transfers can be used to elucidate patterns of senescence in eusocial, non-reproducing individuals like the honey bee worker.
Why is dominance hierarchy age-related in social insects? The relative longevity hypothesis
Behavioral Ecology and Sociobiology, 2005
In temperate regions, older eusocial hymenopteran females with annual life cycles (annualtemperate) tend to dominate younger females, a behavior demonstrated by many Polistes. However, in queenless ponerine ants and primitively eusocial tropical wasps (perennial/tropical), a younger female can be dominant and occasionally takes over from the older, most dominant reproductive female, the alpha. We investigated these patterns using an inclusive fitness model. The most important difference between the above two cases lay in the length of individual life compared with colony life. Colonies dissolve before winter in the annual-temperate case, so the expected future tenure of the replacement alpha is never longer than that of the original alpha. This makes the non-reproductive subordinate tactic more advantageous for individuals that emerge later in the season because of the fitness cost of superseding. The perennial/tropical case does not have a clear upper limit for colony longevity, so the model predicts that late-born younger daughters are more likely to challenge their mother-alpha because of the expected long future tenure of the new alpha compared with the small indirect cost of the mother's reproductive failure. To switch tactics from being a subordinate to being the new alpha is only optimal in some situations.
Ageing and somatic maintenance in social insects
Current Opinion in Insect Science, 2014
Social insects offer exciting prospects for ageing research due to the striking differences in lifespan among castes, with queens living up to an order of magnitude longer than workers. A popular theory is that senescence is primarily the result of an accumulation of somatic damage with age, balanced by investment into processes of somatic maintenance. Investigation of these predictions in social insects has produced mixed results: neither damage accumulation nor investment into somatic maintenance is consistently different between castes with different lifespans. We discuss some limitations of the studies conducted thus far and consider an alternative proximate theory of ageing that has been recently proposed.