Changes in gene expression and viral titer in Varroa jacobsoni mites after a host shift from Asian to European honey bees

Andino, Gladys K. Ph.D., Purdue University, December 2014. Changes in gene expression and viral titer in Varroa jacobsoni mites after a host shift from Asian to European honey bees. Major Professor: Greg J. Hunt. Honey bees (Apis mellifera L.) are the most important insects for the pollination of crops and wildflowers. However, they have experienced increasing colony die-offs during the past two decades. Multiple species of parasitic mites have been described that affect honey bees. The most important species in beekeeping belong to the genus Varroa (Varroa jacobsoni and Varroa destructor). Varroa mite parasitism of honey bees is thought to be the most significant cause of colony mortality worldwide, and mite resistance to active ingredients of acaricides has become common. V. destructor causes direct impacts on bee production as well as indirect effects on bee health by vectoring viruses and other pathogens. These large ectoparasitic mites are associated with a condition known as parasitic mite syndrome, or PMS. When colonies exhibit PMS pathogens, brood diseases and viruses are present at unusually high levels. The open wound caused during feeding can allow microorganisms to enter and weaken the host, and mites themselves are vectors for viruses and perhaps other bee pathogens. There are a number of studies that also suggest that the primary cause of colony mortality is the viruses associated with the mites. Until recently, Varroa jacobsoni was known to only live and reproduce in Asian honey bee (Apis cerana) colonies while V. destructor