The honeybee is a eusocial insect, which means that it is characterized by reproductive division of labor and by the presence of a facultatively sterile worker caste that engages in alloparental care behaviors such as brood care and foraging. Eusocial insect societies are found in the orders Hymenoptera (ants, wasps, and bees) and Isoptera (termites). Within these genera, the honeybee is among the most socially advanced. It is also the species with the best developed tool kit for husbandry, and constitutes, by far, the best studied social insect (reviewed by Winston, 1987).
The honeybee receives considerable attention in studies that aim to understand how complex collective patterns emerge from interactions between individuals. It is, consequently, a key research model in behavioral ecology (e.g., Calderone and Page, 1992; Huang and Robinson, 1996; Trumbo et al, 1997; Pankiw and Page, 2001), neurobiology (Scheiner et al., 2001; Humphries et al., 2003), and systems theory (e.g., Omholt, 1987; Bonabeau, 1998; Page and Erber, 2002; Amdam and Omholt, 2003). In addition, eusocial insects can make important contributions to our understanding of aging across levels of biological complexity (Rueppell et al., 2004). This is in part because of caste-specific gene expression programs, which have emerged through social insect evolution
(Evans and Wheeler, 2001). These programs may underlie trajectories of senescence and longevity regulation that show considerable variation between castes, both within and between species of the social Hymenoptera and Isoptera (for further information see Finch, 1990; Rueppell et al., 2004). In this context, the honeybee worker caste also provides an additional regulatory layer of interest (Omholt and Amdam, 2004): within this caste the rate of senescence does not appear to be a function of chronological age (Amdam and Page, 2005). Rather, aging in honeybee workers is state-dependent (reviewed by Amdam, 2005), and longevity is—as a result— a function of a plastic progression through life-cycle stages with distinct behavioral and physiological profiles. This succession generates a facultative age-determination pattern of particular interest to research on aging and longevity (Omholt and Amdam, 2004; Amdam, 2005). It has therefore, been predicted that, in parallel with the development of new functional genomic tools (Beye et al., 2002; Amdam et al., 2003b) and the availability of the honeybee genome sequence (www.hgsc.bcm.tmc.edu), the bee will grow to become the most noteworthy social invertebrate model for senescence (for discussions see Rueppell et al., 2004; Amdam and Page, 2005).
Rooted in these perspectives, we here provide an introductory overview aimed at researchers who are interested in using the honeybee as a gerontological model. We present a summary of the general biology of the bee, and outline the behavioral and physiological life trajectories that are specific to the different honeybee castes. The link between the plasticity of these trajectories and the dynamics of the honeybee society as a whole is emphasized. Subsequently, we present a preparative review of key handling procedures and sources of methods for studies of the bee, in which we elucidate how social integrity can be maintained under the experimental management of free-flying colonies as well as for individuals kept in a laboratory setting. We next provide examples of the use of honeybees in aging research—a section that also serves to outline the current status of the field in mechanistic and biodemographic terms. Finally, we discuss how social insects, in a wider taxonomic perspective, can contribute to the understanding of aging, and we outline future prospects for use of the honeybee as a gerontological model.
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