Since 2006, commercial honeybees have been dying in massive numbers. A new study links Tobacco ringspot virus (TRSV) as a potential cause of colony collapse disorder.
TRSV was connected to a rising tide of bee deaths, which increase in fall and peak in the winter. The virus is likely picked up during bees foraging and spread as the colony mixes the pollen, saliva, and nectar to produce food for juveniles. TRSV may also be spread by ectoparasitic Varroa mites, which feed on bee hemolymph, without being infected themselves.
TRSV was found most highly concentrated in the bee’s nervous system and wings, but was also found in the hemolymph, body fat, and legs.
Tobacco ringspot is an RNA virus. TRSV is a rapidly mutating virus (not surprising as it is a single-stranded RNA virus), and likely spread to bees by first adapting to soy plants from tobacco plants. The study showed that the virus can replicate and produce virions in honeybees, Apis mellifera. Furthermore, the study showed that TRSV infected individuals were a continual presence in several monitored colonies.
Potential ways to prevent the spread of TRSV include increased surveillance for virus “host-shifting” events and understanding better how plant viruses shift hosts.