Abstract:SummaryPositive social contact is an important factor in healthy aging, but our understanding of how social interactions influence senescence is incomplete. As life expectancy continues to increase because of reduced death rates among elderly, the beneficial role of social relationships is emerging as a cross-cutting theme in research on aging and healthspan. There is a need to improve knowledge on how behavior shapes, and is shaped by, the social environment, as well as needs to identify and study biological … Show more
“…Eusociality has had profound consequences for the evolution of behavioural development, immune function and genetic regulation of ageing [17,18,19]. Social interactions appear to mediate metabolic homeostasis and affect mortality rates [74].…”
Section: Discussionmentioning
confidence: 99%
“…Few studies have examined the influence of sociality on ageing and life history [11][12][13], and little is understood about cognitive decline and neurobiological changes accompanying senescence in social animals, apart from humans [12,[14][15][16]. Social insects have striking lifespan polyphenisms [17][18][19][20]: queens often live more than a decade, whereas workers may live only several months [21], indicating that the differentiation of reproductive and sterile castes has had profound effects on senescence, which may be influenced by the social organization of colony labour. The relationship of task performance to age-related changes in the worker brain, however, is not well understood.…”
Analyses of senescence in social species are important to understanding how group living influences the evolution of ageing in society members. Social insects exhibit remarkable lifespan polyphenisms and division of labour, presenting excellent opportunities to test hypotheses concerning ageing and behaviour. Senescence patterns in other taxa suggest that behavioural performance in ageing workers would decrease in association with declining brain functions. Using the ant Pheidole dentata as a model, we found that 120-day-old minor workers, having completed 86% of their laboratory lifespan, showed no decrease in sensorimotor functions underscoring complex tasks such as alloparenting and foraging. Collaterally, we found no age-associated increases in apoptosis in functionally specialized brain compartments or decreases in synaptic densities in the mushroom bodies, regions associated with integrative processing. Furthermore, brain titres of serotonin and dopamine-neuromodulators that could negatively impact behaviour through age-related declines-increased in old workers. Unimpaired task performance appears to be based on the maintenance of brain functions supporting olfaction and motor coordination independent of age. Our study is the first to comprehensively assess lifespan task performance and its neurobiological correlates and identify constancy in behavioural performance and the absence of significant age-related neural declines.
“…Eusociality has had profound consequences for the evolution of behavioural development, immune function and genetic regulation of ageing [17,18,19]. Social interactions appear to mediate metabolic homeostasis and affect mortality rates [74].…”
Section: Discussionmentioning
confidence: 99%
“…Few studies have examined the influence of sociality on ageing and life history [11][12][13], and little is understood about cognitive decline and neurobiological changes accompanying senescence in social animals, apart from humans [12,[14][15][16]. Social insects have striking lifespan polyphenisms [17][18][19][20]: queens often live more than a decade, whereas workers may live only several months [21], indicating that the differentiation of reproductive and sterile castes has had profound effects on senescence, which may be influenced by the social organization of colony labour. The relationship of task performance to age-related changes in the worker brain, however, is not well understood.…”
Analyses of senescence in social species are important to understanding how group living influences the evolution of ageing in society members. Social insects exhibit remarkable lifespan polyphenisms and division of labour, presenting excellent opportunities to test hypotheses concerning ageing and behaviour. Senescence patterns in other taxa suggest that behavioural performance in ageing workers would decrease in association with declining brain functions. Using the ant Pheidole dentata as a model, we found that 120-day-old minor workers, having completed 86% of their laboratory lifespan, showed no decrease in sensorimotor functions underscoring complex tasks such as alloparenting and foraging. Collaterally, we found no age-associated increases in apoptosis in functionally specialized brain compartments or decreases in synaptic densities in the mushroom bodies, regions associated with integrative processing. Furthermore, brain titres of serotonin and dopamine-neuromodulators that could negatively impact behaviour through age-related declines-increased in old workers. Unimpaired task performance appears to be based on the maintenance of brain functions supporting olfaction and motor coordination independent of age. Our study is the first to comprehensively assess lifespan task performance and its neurobiological correlates and identify constancy in behavioural performance and the absence of significant age-related neural declines.
“…Based on this study alone, it cannot be firmly excluded that MDA-protein adduct levels were not influenced by factors other than rain and access to flight. For instance, we did not control for any non-foraging behavior or social factors such as the activity level of individual bees and their location in the hive (Riessberger and Crailsheim, 1997;Stabentheiner et al, 2010;Amdam, 2010). Still, in light of apparent discrepancies from the oxidative stress theory of ageing in previous studies with D. melanogaster (Cook-Wiens and Grotewiel, 2002) and rats (Ogonovszky et al, 2005), it is nonetheless plausible that long foraging experience in honeybee workers induces learning impairment through mechanisms that do not directly involve oxidative stress or that an acclimatisation response to foraging activity can enhance protection toward lipid peroxidation and resulting levels of protein damage.…”
SUMMARYHoneybees (Apis mellifera) senesce within 2weeks after they discontinue nest tasks in favour of foraging. Foraging involves metabolically demanding flight, which in houseflies (Musca domestica) and fruit flies (Drosophila melanogaster) is associated with markers of ageing such as increased mortality and accumulation of oxidative damage. The role of flight in honeybee ageing is incompletely understood. We assessed relationships between honeybee flight activity and ageing by simulating rain that confined foragers to their colonies most of the day. After 15days on average, flight-restricted foragers were compared with bees with normal (free) flight: one group that foraged for ~15days and two additional control groups, for flight duration and chronological age, that foraged for ~5days. Free flight over 15days on average resulted in impaired associative learning ability. In contrast, flight-restricted foragers did as well in learning as bees that foraged for 5days on average. This negative effect of flight activity was not influenced by chronological age or gustatory responsiveness, a measure of the bees' motivation to learn. Contrasting their intact learning ability, flight-restricted bees accrued the most oxidative brain damage as indicated by malondialdehyde protein adduct levels in crude cytosolic fractions. Concentrations of mono-and poly-ubiquitinated brain proteins were equal between the groups, whereas differences in total protein amounts suggested changes in brain protein metabolism connected to forager age, but not flight. We propose that intense flight is causal to brain deficits in aged bees, and that oxidative protein damage is unlikely to be the underlying mechanism.Supplementary material available online at
“…Additionally, low levels of AmILP1 transcripts in the fat body of adult bees are linked to high blood sugar levels (Wang et al, 2012). In contrast, the regulation and function of AmILP2 is less well understood as AmILP2 expression does not consistently respond to factors as AmILP1 does in adult honey bees (Amdam, 2011;Wheeler et al, 2006).…”
SUMMARYThe food a honey bee female larva receives determines whether she develops into a large long-lived fertile queen or a short-lived sterile worker. Through well-established nutrient-sensing and growth-promoting functions in metazoans, the insulin/insulin-like growth factor 1 signaling (IIS) pathway has become a focal topic in investigations on how differences in food environment can be translated into internal signals responsible for queen-worker determination. However, low expression levels of two insulin receptors (AmInRs) in honey bee larvae and the failure of one AmInR to influence caste differentiation are in potential conflict with such a classical growth-promoting role of IIS in queen-worker development. In view of such an apparent contradiction, and the fact that binding partners and affinities of these two AmInRs have not been worked out, we performed a functional study on insulin-like peptide genes (AmILP1 and AmILP2) in honey bee larvae by using a double-stranded RNA (dsRNA)-mediated gene knockdown approach. We found that juvenile hormone (JH) levels were diminished by AmILP1 dsRNA treatment, while the AmILP2 knockdown caused a reduction in ovary size. Blood sugar titers were not significantly affected by the treatments. From these results we conclude that AmILP2 transcript levels may influence specific organ development, such as the ovary and body mass, while more general traits of caste differentiation, such as mandibles, may require additional regulators. In addition, JH production may be regulated by AmILP1 expressed locally in the brain, similar to the function of certain ILPs in Drosophila.
Supplementary material available online at
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