My first two years of graduate work have concentrated on the influence
of protein availability on the ability of honey bees to overwinter.
Brood rearing ceases in colonies in late fall and the workers produced
at this time are long-lived "winter" bees that cluster within the
colony from late fall to spring. Winter bees are characterised by
hypertrophied fat bodies and hypopharyngeal glands, which are two major
locations of internal protein storage.
Aside from internal worker
reserves, protein is also stored externally as pollen in the honey
comb. Over the winter, bees utilise these resources to provide protein
for the nutrition of developing larvae.
A colony must begin rearing
young replacement bees in late winter in order to build colony strength
for the spring, long before adequate pollen foraging conditions exist.
When fall or spring pollen supply is limited, protein-starved colonies
will have to compromise the quality and/or quantity of the workers that
are produced for and by the overwintering population. Previous studies
have demonstrated that protein status plays an important role in the
ability of colonies to overwinter, but the influence of protein
availability on the development of the overwintering population and the
spring population that it produces remains poorly understood.
In my first field season, I examined the trade-offs made in the
production of spring workers by overwintered colonies that were
pollen-stressed (low pollen) or pollen-rich (high pollen) prior to
spring foraging. I estimated both the quantity (area of sealed brood)
and the quality (weight, size, asymmetry, total protein content,
longevity and nursing behaviour) of workers reared by these colonies in
the spring, as well as honey production in the following summer.
Colonies that had pollen supplements in early
spring produced two to four times more brood than control and pollen
restricted colonies, respectively, and only supplemented colonies
reared brood in significant amounts before natural pollen foraging
began.
