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

Abstract

The ectoparasitic mite Varroa destructor (Anderson & Trueman) is the most destructive pest of the honey bee, Apis mellifera L., 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.

Transcriptional signatures of parasitization and markers of colony decline in Varroa-infested honey bees (Apis mellifera)

“…Although vitellogenin dynamics are complicated (Amdam et al, 2004b), the observed down regulation of vitellogenin supports a possible accelerated behavioural maturation of these bees.…”

“…Additionally, high vitellogenin titers keep juvenile hormone levels low, thereby slowing behavioural maturation to foragers and potentially initiating the production of long-lived winter bees (Doke et al, 2015;Fluri et al, 1982). Previous studies have found that parasitization with Varroa produced workers that accumulate significantly fewer haemolymph proteins, including vitellogenin (Amdam et al, 2004b). Other studies found that Fig.…”

Intergenerational transfers may have decoupled physiological and chronological age in a eusocial insect

“…The dotted line exemplifies the investment in a bee that receives little or no proteinacious jelly after emergence. The dynamics match the relative vitellogenin concentrations of the bees accurately (e.g., Engels and Fahrenhorst, 1974;Fluri et al, 1982;Amdam et al, 2004a).…”

Interaction betweenVarroa destructorand imidacloprid reduces flight capacity of honeybees

“…Moreover, flight is vital for foraging success as foraging for nectar and pollen sometimes involves several hours of flying a day and carrying heavy loads [14,18]. Negative effects on foraging performance may reduce pollen availability in the colony (as suggested by Wolf et al [16]), which reduces the number of reared bees [19], weakens newly hatched bees by reduced body mass and protein content [20,21], and induces precocious foraging [22,23]. A reduced food-collecting ability due to multiple stressors may ( partly) prevent the coping mechanism of precocious foraging, while the purpose of precocious foraging is to replenish the colony resources.…”