Learning at old age: a study on winter bees

Abstract

Ageing is often accompanied by a decline in learning and memory abilities across the animal kingdom. Understanding age-related changes in cognitive abilities is therefore a major goal of current research. The honey bee is emerging as a novel model organism for age-related changes in brain function, because learning and memory can easily be studied in bees under controlled laboratory conditions. In addition, genetically similar workers naturally display life expectancies from 6 weeks (summer bees) to 6 months (winter bees). We studied whether in honey bees, extreme longevity leads to a decline in cognitive functions. Six-month-old winter bees were conditioned either to odours or to tactile stimuli. Afterwards, long-term memory and discrimination abilities were analysed. Winter bees were kept under different conditions (flight/no flight opportunity) to test for effects of foraging activity on learning performance. Despite their extreme age, winter bees did not display an age-related decline in learning or discrimination abilities, but had a slightly impaired olfactory long-term memory. The opportunity to forage indoors led to a slight decrease in learning performance. This suggests that in honey bees, unlike in most other animals, age per se does not impair associative learning. Future research will show which mechanisms protect winter bees from age-related deficits in learning.

Aging and its modulation in a long-lived worker caste of the honey bee

“…Experimental restriction of daily flight periods further suggests that metabolically demanding flight activity is causally linked to a shortened lifespan (Neukirch, 1982), and to the agerelated decline of learning function in foragers (Tolfsen et al, 2011). Few studies so far have explored the aging dynamics of winter bees (Behrends and Scheiner, 2010;Lindauer, 1963;Seehuus et al, 2006a), but the results suggest that organismal integrity, learning and memory are not compromised despite high chronological age.…”

Increased brood viability and longer lifespan of honeybees selected for propolis production

“…This indicates that environmental factors affect worker longevity (Seeley 1995;Remolina and Hughes 2008). Even old worker bees can display normal olfactory and tactile acquisition and discrimination, although they have a slightly impaired long-term olfactory memory (Behrends and Scheiner 2010). Simone-Finstrom and Spivak (2010) reported that social immunity is a promising area of study in social insect biology.…”

Accelerated behavioural development changes fine-scale search behaviour and spatial memory in honey bees (Apis melliferaL)

“…Age-related changes in cognitive performance of foragers have been reported in terms of a decline in the cognitive performance in older foragers that have accumulated more than 2 weeks of foraging experience (Behrends and Scheiner, 2010;Behrends et al, 2007;Scheiner and Amdam, 2009). This is interpreted as senescence caused more by the accumulated demands of foraging than chronological age, and is evidence that prolonged foraging causes cognitive ageing in a bee (Behrends and Scheiner, 2010;Behrends et al, 2007;Scheiner and Amdam, 2009).…”

“…This is interpreted as senescence caused more by the accumulated demands of foraging than chronological age, and is evidence that prolonged foraging causes cognitive ageing in a bee (Behrends and Scheiner, 2010;Behrends et al, 2007;Scheiner and Amdam, 2009). In our experiments, foraging experience was not precisely controlled and therefore could cognitive decline explain the difference in performance between precocious and normal-aged foragers?…”

“…Research suggests several phases to the cognitive life of a honey bee: an early phase during which sensory systems are still maturing (Allan et al, 1987;Masson and Arnold, 1984;Morgan et al, 1998), a middle phase when bees can perform at their cognitive best, and a later phase during which cognitive decline may occur (Behrends and Scheiner, 2010;Behrends et al, 2007;Scheiner and Amdam, 2009). Our data suggest that bees in the first 2 weeks of adult life have not developed the full cognitive capacity of normal-aged foragers, with the implication being that cognitive development is still ongoing during the first 2 weeks after adult emergence.…”