What Is Tobacco Ringspot Virus? A Beekeeper’s Guide

A beekeeper inspecting a hive for diseases like Tobacco Ringspot Virus

Tobacco Ringspot Virus (TRSV) is a pathogenic virus that affects a wide range of plant species. It was first discovered in America’s tobacco fields in 1927.

TRSV belongs to the Nepovirus genus and can cause significant yield reductions in affected crops. Infected plants typically display symptoms such as yellowing and characteristic ring spots on leaves.

A magnified image of the tobacco ringspot virus (TRSV)
Tobacco ringspot virus under magnification.

The virus impacts plants from 35 families, including tobacco, beans, cucumbers, and tomatoes.

Tobacco ringspot virus and the honey bee

In 2014, researchers published an article in the mBio journal that shook the beekeeping world. In a fascinating revelation, they found cases of honey bees with the Tobacco ringspot virus.

Their discovery was unexpected because TRSV is a plant virus not previously known to infect animals.

Cross-kingdom viral jumps have occurred before in history. The leap from HIV in chimpanzees to humans was big news in the early 1900s. But these two species are only several million years apart on the evolution timeline. Honey bees and TRSV are considered 1.6 billion years apart, making the viral jump seemingly impossible.

How do honey bees contract the virus?

Worker bees collect pollen contaminated with TRSV during their regular foraging trips. The food source is then transported back to the colony, where it gets ingested.

Why is TRSV in bees significant?

Plant and animal cells have fundamentally different structures. This variance protects animals from contracting plant viruses. However, scientists were amazed when they discovered that the Tobacco ringspot virus had spread to honey bees. It is the first plant virus ever to make the jump to bees.

Can bees transmit the disease to plants?

While the disease is transmittable from plant to insect, scientists have no evidence of bee-to-plant transmission.

Closeup image showing the signs of TRSV on a leaf
Signs of TRSV on a plant leaf.

How does TRSV affect honey bees?

The tobacco ringspot virus is believed to shorten a bee’s life. It affects the insect’s wings, gut, blood, antennae, and various other parts of the anatomy.

Tobacco ringspot virus is a relatively new pathogen, so scientists are still studying the severity of this disease in honey bees.

In one study, researchers monitored strong and weak hives for a year, looking at the relationship between the virus and colony collapse disorder. They also looked at other common bee viruses in the study.

Results showed that CCD was more likely in hives with higher concentrations of tobacco ringspot virus and other viruses.

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5 fast facts about tobacco ringspot virus

  1. The infection is part of the plant virus family Secoviridae.
  2. It moves to new plants by seed transmission, sap inoculation, and insects like thrips, flea beetles, mites, and grasshoppers.
  3. Varroa mites are a vector for transmitting TRSV between bees.
  4. The virus came close to destroying the tobacco industry.
  5. TRSV gets its name from the characteristic ringspot that shows on infected plants.

Research summary

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

Published: Jan, 2014.

Research summary: Emerging diseases from pathogen host shifts pose health risks to humans and other species. RNA viruses significantly contribute to such diseases with their high mutation rates.

This study found that the tobacco ringspot virus (TRSV), usually a plant pathogen, can also infect honeybees.

The virus was detected throughout the year in colonies. Its increasing prevalence, along with other bee viruses, was linked to colony decline and winter collapses.

Varroa mites were found to carry the virus, suggesting its role in TRSV spread among bees. However, the virus was confined to a specific area in mites, indicating no systemic invasion.

Phylogenetic analysis showed TRSV from bees, pollen, and mites shared a common evolutionary origin with plant TRSVs. This suggests a unique cross-kingdom host shift.

The discovery that plant virus’ can also infect honeybees emphasizes the risk of diseases emerging from host shifts. With around 5% of plant viruses being pollen transmitted, they present potential sources for future hosts. Monitoring shifts in pollinator management programs is vital.

Read the research>

If you enjoyed reading this article, also check out our guides to chronic bee paralysis virus and Kashmir bee virus.

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