Systemic Spread and Propagation of a Plant-Pathogenic Virus in European Honeybees, Apis mellifera

Li, Ji Lian; Cornman, R. Scott; Evans, Jay D.; Pettis, Jeffery S.; Zhao, Yan; Murphy, Charles; Peng, Wen Jun; Wu, Jie; Hamilton, Michele; Boncristiani, Humberto F.; Zhou, Liang; Hammond, John; Chen, Yan Ping

TRSV isolates from honeybees, Varroa mites, and bee pollen clustered together phylogenetically, indicating that they descended from a common ancestor. It is likely that Varroa mites obtained the virus from their hosts during the blood feeding and that the virus-infected bees contaminated the bee pollen when they mix plant pollen with their glandular secretions and honey to produce "bee bread." The finding that TRSV isolates from honeybees appeared to be derived more recently on the evolutionary timeline than TRSV from plants suggests that life cycles of the virus involving arthropod hosts evolved after host expansion. However, it remains to be determined whether TRSV possesses the ability to maintain persistent infection in honeybee colonies in the absence of newly inoculated viruses from visited plants or whether infected bees can subsequently inoculate healthy plants. It will similarly be helpful to screen other pollinator species for the presence of TRSV, since it is known that honeybees and other pollinators share some viral species (8) (9) (10) (11) 50) .