The ectoparasitic mite Varroa destructor is the most destructive pest
of the honey bee, Apis mellifera, in Europe and the United States. In
temperate zones, the main losses of colonies from the mites occur
during colony overwintering. To obtain a deeper knowledge of this
phenomenon, we studied the mites' impact on the vitellogenin titer,
the total protein stores in the hemolymph, the hemocyte
characteristics, and the ecdysteroid titer of adult honey bees. These
physiological characteristics are indicators of long-time survival and
endocrine function, and we show that they change if bees have been
infested by mites during the pupal stage.

Compared with noninfested workers, adult bees infested as pupae do not
fully develop physiological features typical of long-lived wintering
bees. Management procedures designed to kill V. destructor in late
autumn may thus fail to prevent losses of colonies because many of the
adult bees are no longer able to survive until spring. Beekeepers in
temperate climates should therefore combine late autumn management
strategies with treatment protocols that keep the mite population at
low levels before and during the period when the winter bees emerge.

Findings suggest that treatments with chemicals or organic acids
intended exclusively to kill V. destructor mites in late autumn may
fail to prevent losses of colonies because the physiology of the bees
has already been impaired. Beekeepers in temperate climates should
therefore combine late autumn management strategies with mid and late
summer treatment protocols to keep the mite population at low levels
before and during the period when the winter bees emerge.

-- 
Altered Physiology in Worker Honey Bees (Hymenoptera: Apidae)
Infested with the Mite Varroa destructor (Acari: Varroidae):
A Factor in Colony Loss During Overwintering?
GRO V. AMDAM

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