This dissertation explores the relationship between metabolic rate, mortality and the foraging behaviour of bees. A basic underlying assumption of some optimal foraging models is that harder working individuals die earlier. A trade-off between foraging activity and longevity may have implications for colony growth, and ultimately for colony reproductive success. Optimality models make quantitative predictions about behaviour from analyses of costs and benefits. When the 'currency' in such models is energy, costs are usually evaluated with metabolic rate data from laboratory studies. Laboratory data often represent pooled results for steady-state activity under standardised conditions, and as such, may bear little resemble to the metabolic costs incurred by individuals in the field. The research presented here uses the non-invasive doubly labelled water method to provide the first direct measurements of field metabolic rate in honeybees and the first direct measurements for bumblebees foraging at natural sources. The results suggest that ecological factors such as ambient temperature or flower-type affect metabolic rate to such an extent that models based on laboratory costs have little or no predictive value. An activity <I>vs.</I> longevity trade-off is tantamount to the 'rate of living' theory of senescence, a theory often invoked to explain mortality in foraging bees. It is a purely mechanistic theory, however, and as such is often opposed on evolutionary grounds: the rate of ageing should be tuned to the pressure of extrinsic mortality (predation, disease and accidents), and senescent death should rarely occur in natural populations.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:595336 |
| Date | January 2000 |
| Creators | Adair, D. E. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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