Virus replication in the honey bee parasite,Varroa destructor

Abstract

ABSTRACTArthropod vectors such as mites and ticks introduce an alternative viral transmission route between their hosts. The ectoparasitic miteVarroa destructoris the leading threat to the health of Western honey bees (Apis mellifera) primarily through its action as a vector of viruses. However, it is unclear whether viruses transmitted byV. destructoractively infect and replicate in mites, which could facilitate increased transmission and select for more virulent strains. To better understand the role ofV. destructoras a vector, we took advantage of differences between bee and mite antiviral RNA interference pathways to identify the host specificity of replicating viruses. We used small RNA sequencing of individualV. destructormites to examine viral small interfering RNA (vsiRNA) profiles of Deformed wing virus genotypes (DWV-A and DWV-B), associated with colony declines, as well as nine other viruses present in our samples. We found active replication of sixV. destructor-associated viruses, including a novel virus, Varroa destructor virus 9 (VDV-9), and replication of two honey bee associated viruses, including both DWV-A and -B genotypes, suggesting that mites are biological vectors for important bee pathogens. We show that the antiviral RNAi response can be used define the host range of viruses in host-parasite interactions, such as honey bees and their parasites, enabling a better understanding of the role of a vector in the evolution and spread of honey bee pathogens.