Thai Sacbrood, a viral disease affecting honey bee colonies, has resurfaced in South India. The disease, which has been dormant in the southern states for some years, is back and impacting the population of bees, especially of the Apis cerana species. This, in turn, can have far-reaching consequences for human life that is indirectly or directly dependant on honey bees.

What’s Thai sacbrood?

Thai sacbrood virus is a variant of sacbrood virus, a viral disease affecting honey bee colonies. Thai sacbrood virus disease was first observed in Thailand in 1976. In 1991-’92, there was an outbreak of the virus in India that resulted in the destruction of more than 90% of the then-existing bee colonies in South India. The disease kills bees when they are larvae, thereby reducing the population of bee colonies.

To identify the diseased combs, the combs are observed for any colour change. The colour of the prepupae (the developmental stage before the pupal stage) changes from white to yellow, then to dark brown. Other symptoms include: the presence of prepupae with raised, pointed heads in the comb cells, and dead larvae that turn into “sac-like” structures filled with fluid. At the age of 10 days, they can be easily removed. Sacbrood virus that attacks Apis mellifera is less virulent when compared to the Thai sacbrood virus.

Apis cerana bees. Photo credit: Denis Anderson, CSIRO/Wikimedia Commons

Significance of bees

Apis cerana or the Asian honey bee is one of the most domesticated species of honey bees in India and it is important to understand the ways to protect their population. Bees are very important for the ecosystem. Humans depend on the bees directly (for honey that has antioxidants and anti-inflammatory properties) and indirectly.

Bees play a crucial role in pollination. Crops produce good yields if animals and insects help them pollinate. And bees are the most dominant pollinators of fruit, vegetable and crop plants. Data reveals that bees visit around 90% of the world’s top 107 crops. In a study published last year in Nature, scientists found evidence that melittin, a component found in honeybee venom, can kill cancer cells.

Apis mellifera, Apis cerana, Apis dorsata, Apis florea and Trigona are the major bee species found in India. Apis cerana is found mainly in south India. Both farmed and wild bees are responsible for the growth and quality of vegetation. Bees are crucial for food security. However, the population of bees worldwide is in decline. It is essential to protect them and be prepared to tackle the viruses that attack their colonies.

Study virus

Apiculture is an important source of additional income for farmers and labourers. Beekeeping has become a major occupation in south India since the 20th century. The Thai sacbrood virus would also affect the livelihood of many such farmers.

Nagendra Sagar, a professional beekeeper and beekeeping demonstrator from Shivamogga, Karnataka, expresses concern over the spread of the Thai sacbrood virus saying, “A few years back we discontinued beekeeping due to the outbreak of this virus in south India. The migration of bees from different states could be one reason for this outbreak. Now, we see Thai sacbrood virus active again in the bee colonies of the Western Ghats in Karnataka.”

Sagara added, “As apiarists, we need more understanding of Thai sacbrood virus to be able to control it. Since it does not affect humans, we speculate that the scientific community is ignoring the spread. So, there is no major research happening in this field.”

It is also crucial that more scientists and researchers work on this because the Thai sacbrood virus may spread to other parts of the world and may not be contained within south India. By studying the Thai sacbrood virus we may be warned of the next viruses that may harm the bees too.

Thai Sac Brood virus disease attacking Indian honey bees has been posing a threat to hives of Apis cerana. Photo credit: Chinmaya KV

Protecting bees

The method most recommended to control the spread of the disease, is to remove the infected honeycombs that contain the dead larvae, and burn them. This virus also spreads through humans, similar to SARS-COV2. If a person touches infected colonies and then touches healthy boxes, the virus surges to other boxes as well. It is recommended that the people responsible, always wash their hands with soap before touching new boxes. A recent study suggests isolating the queen bee from the other working bees in the colonies to manage the spread. However, there is no clear protocol to save the honey bees from the Thai Sac Brood virus.

The Chairman of the Biodiversity Board, Karnataka, Ananth Hegde Ashisar, assures that the scientists will resolve this and come up with a clear solution very soon. “The Karnataka Biodiversity Board is planning to declare the honey bee as a ‘state insect’, considering its importance in the ecosystem,” he added. “Regarding the Thai Sac Brood virus, we regret to inform you that our scientists and concerned officers are not following it up with the government and beekeepers. We have informed the concerned minister and officials to look into it.”

Scientific beekeeping and monitoring the viruses in different species of bees are essential to make sure the Thai sacbrood virus does not spread any further.

This article first appeared on Mongabay.