Honeybees are dying in large numbers globally, and this tragedy has many root causes. One of them is the deadly deformed wing virus, which is transmitted to bees by the parasite known as varroa mite and can infect bees throughout their lifecycles. Varroa mite is associated with colony collapse disorder (CCD) that has plagued honeybees for many years.
One way this deadly virus manifests, in addition to killing them, is that it impairs their sense of direction and ability to return to their colony after a foraging expedition.
According to a study in the journal iScience published on September 28, 2021, researchers demonstrate that there is a cheap and natural chemical compound that has the ability to reverse or prevent the effects of this virus in bees.
The researchers monitored hives and showed that bees fed the compound were way more likely to return to the hive after a foraging trip. Bees fed the compound before being infected were 9 times more likely to survive the virus after 5 days. Severely infected bees died within days or had poorly developed wings that hindered the ability to fly and forage. Previous research had already shown that the virus weakens a bee’s memory and learning. This also affects a bee’s ability to get home after hunting for food. Lost bees can die, and their colony may collapse due to lack of sustenance.
This unrelated 4:00-minute video by Hayfield Hives Beekeeping shows some honeybees with DWV:
First author Cheng-Kang Tang at National Taiwan University says pathogens are a definite stressor for bees, but beekeepers don’t want to use pesticides due to food safety concerns. This caused them to find compounds that increase the strength of bees.
Their findings revealed that the virus suppressed the expression of genes associated with nerve signal transmission and other biological processes related to learning and memory functions. The team identified sodium butyrate (NaB) as a potential candidate to protect them from it. NaB is a chemical compound known to increase the expression of various genes in animals, and it is found in many plants including those involved in immune responses and learning.
Lead author Yueh-Lung Wu at National Taiwan University and his team fed honeybees with NaB-laced sugar water for a week to investigate NaB’s effects on them. Then they infected them with the deformed wing virus. Over 90% of these bees stayed alive after five days, compared to 90% of infected bees that didn’t get NaB dying over the same period.
For those who want to see what happened with the previous video, here is Part 2 but it is longer at 14:15-minutes:
Wu says these findings show that feeding the insects with NaB before virus exposure can counteract the negative impacts of the pathogen. They previously found that NaB can upregulate immune response genes in bees, which helps suppress viral replication and improves bees’ survival chances.
Wu’s team experimented at a bee farm by putting monitors at the entrance of several beehives for a month to calculate how many bees come and go daily — each hive had tens of thousands of foraging bees. The researchers found that an average of half the infected foragers returned to the hive. But of the bees fed with NaB sugar water before being infected, over 80% found their way home by the end of the day. This is a comparable level to uninfected bees.
As Wu says, the study tested the effect of NaB on bees across some scales, at the genetic level, to behaviors in the lab, then in the field in a natural scenario. Next, they will observe if bees respond to the NaB supplement differently across seasons, since bees change their behavior throughout the year.
Since sodium butyrate is really cheap, it would be an easy and affordable approach for beekeepers to keep their bees alive, if its benefits are proven, Wu says. Honeybees are important pollinators of a wide variety of fruits and vegetables and therefore have global economic importance as being crucial to maintaining the balance of the ecosystem.