If one were to ask how long a bee lives, the typical answer is six
weeks: the first three weeks performing in-hive tasks (such as
nursing, comb building, and honey processing), and the last three
weeks for out-hive tasks (foraging). This textbook answer is
misleading in several ways.

First, it is clearly referring only to worker bees, and not queens or
drones (who live a few years and a few weeks, respectively). Second,
there is a lot of variation in worker lifespan and the tasks they
perform. Some bees can start foraging less than a week old and die
soon thereafter, while others may never forage and live for 60 days or
more.

Third, such an answer refers to the typical lifespan of bees during
the active season. This neglects how long bees can live during the
non-active months, which in some regions of the country can last as
long as half the year. So-called "winter" bees are reared in the late
fall and stay alive in the winter cluster for months, far longer than
the lifespan quoted from the standard textbook.

What's interesting about these long-lived winter bees is that they are
not different genetically from their summer-time sisters; that is, a
queen lays the same types of eggs sired by the same types of drones
during both the summer and late autumn. What is different about the
winter bees is that they are different physiologically, so that their
internal cellular machinery causes the workers to have markedly
different characteristics. These differences are manifested by the
interaction with the environment, so that genes are differentially
turned on or turned off depending on the bee's surroundings to create
these physiololgical differences. In particular, the main stimulus for
winter bees to develop is a queenright colony without any brood for
their first 3 to 4 weeks of adult life.

If the brood environment has such a profound effect on a winter bee's
physiology, then it stands to reason that other major environmental
factors may effect this process as well. Most notably, parasitism by
the varroa mite might well cause significant changes in how winter
bees develop at the end of the summer. It is this effect that a
research team lead by Gro Amdam from Norway investigated in a study
published in the Journal of Economic Entomology.

Amdam, G. V., K. Hartfelder, K. Norberg, A. Hagen, and S. W. Omholt.
(2004). Altered physiology in worker honey bees (Hymenoptera: Apidae)
infested with the mite Varroa destructor (Acari: Varroidae): a factor
in colony loss during winter? Journal of Economic Entomology, 97:
741-747.

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