Varroa destructor mite infestations in capped brood cells of honeybee workers affect emergence development and adult foraging ability

Given recent higher declines in managed Apis mellifera honeybees,which are the most commonly managed bee species around the world(Garibaldi et al.2013),numerous health threats involved in the losses have been received great attention.To date,Varroa destructor mite infestation has become the biggest challenge in commercial beekeeping,which is considered as a thorn stuck in the throat of beekeepers.The Varroa mite threatens bee health by absorbing the fat body and hemolymph of immature and mature bees(Ramsey et al.2019).Varroa mite infestation during the development of worker bees was found to reduce birth weight,influence water content and protein level in hemolymph of newly emerged worker bees,decrease flight performance of drones,change gene expression patterns related to immune system of honeybees,and result in honeybee colony losses(Duay et al.2002;Bowen-Walker and Gunn 2010;Zhang et al.2010;Annoscia et al.2012;Dooremalen et al.2013;Locke 2016).The Varroa mite,as an ectoparasite of the honeybee,prefers living in the sealed brood cells(Bogdanov 2006).Thus,bees are more likely to become hosts of mites in the pupal stage.In this study,we systematically investigated the current impacts of V.destructor infestations on the development from capped larvae to emerged bees.