Senescence in the worker honey bee Apis Mellifera

Honey bees are social insects that exhibit striking caste-specific differences in longevity. Queen honey bees live on average 1-2 years, whereas workers live 2-6 weeks in the summer and about 20 weeks in the winter. It is not clear whether queen-worker differences in longevity are due to intrinsic physiological differences in the rate of senescence, to differential exposure to extrinsic factors such as predation and adverse environmental conditions, or both. To determine if the relatively short lifespan of worker bees involves senescence, we measured age-specific resistance to three different physiological stressors (starvation, thermal, and oxidative stress) while eliminating age-related differences in foraging activity and minimizing age-related differences in energy expenditure. Despite these manipulations, older worker bees were still significantly less resistant to all three stressors than were younger bees. These results indicate that the regulation of worker bee lifespan involves senescence, in addition to extrinsic factors.