Deadly Virus Turns Honey Bees Into Trojan Horses, Rapidly Spreading the Infection to Healthy Hives

 

Researchers have found that honey bees that guard hive entrances are twice as likely to let in intruders from other hives if they are infected with the Israeli acute paralysis virus, a deadly bee pathogen. 

The findings of their most recent study, published in the Proceedings of the National Academy of Sciences, strongly suggest that I-A P V infection alters the behavior and physiology of honey bees in ways that increase the virus's spread. 

The most significant result of our study is that I-A P V infection increases the likelihood of infected bees being accepted by foreign colonies, according to lead researcher Adam D O L E Z A L, an entomology professor at the University of Illinois at Urbana-Champaign. "The infected bees are able to get around the guards of foreign colonies in a way that they shouldn't, but somehow they are able to do so" 

Researchers tagged each bee with the equivalent of a QR code and continuously monitored their interactions to record their behavior. As many as 900 bees could be monitored simultaneously by the researchers. 

This automated system for studying bees engaged in prophylaxis, a process by which honey bees exchange regurgitated food and other liquids, was developed in previous research by study co-author and U of entomologist Gene Robinson and his colleagues. They investigated how I-A P V infection might affect the bees' prophylaxis social network with this system

Prophylaxis allows honey bees to share hormones and food with one another. Researchers discovered that this behavior makes it possible for viral infections to spread through a hive. Honey bees changed their behavior in response to infection in their own hives, according to Illinois researchers

The researchers looked at the chemistry of the hydrocarbons that cover the bees' exoskeletons to see if the I-A P V infected bees were emitting a different chemical odor than their healthy nest mates. They found that healthy bees, I-A P V infected bees, and immune stimulated bees all had distinct hydrocarbon profiles. 

D O L E Z A L stated, "It appears that the virus is changing how the bees smell, and perhaps the infected bees are also behaving in a manner that is meant to appease the guards by engaging" 

He said that the new findings suggest that I-A P V is changing in ways that make it more likely to infect as many hosts as possible. 

I-A-P-V may alter the abundance of various hydrocarbons, which differed between the healthy and sick groups, which may explain why it is so successful at fooling the guards. For instance, they discovered that I-A P V infection levels decreased, which have been linked to increased acceptance by other bees. When challenged by guards, the sick bees were also more likely to give them food and to be submissive, which may have helped them spread the disease. 

These bees can cause more than just the I-A-P-V virus. The newcomers may also be carrying the mite, a parasite that has decimated bee populations worldwide. The mite can carry IAV and other deadly viruses and feed on bees' fat stores. Commercial beekeepers who group their colonies together for efficiency may face a significant challenge if I-A P V aids in the spread of these other pathogens. "If you suspect a virus infection, there is very little you can do," he states

He stated, "If you're a virus, it's much more valuable to be passed on to a new family, like moving from one city to another". How do you get there, then? You make it more likely that the sick bees that leave colony A will enter colony B