Engineered bacteria for protecting bees from pests and pathogens
Honeybees, as little they are in size, these small hero’s play a crucial part in our ecosystems. They play an enormous role in global food chains and food webs. Without honey bees, dozens of crops, from almonds to berries, are likely to vanish. Honey bees contribute nearly $20 billion each year to the value of U.S. crop production. It is estimated that one-third of the food that we consume each day relies on pollination mainly by bees.
But recently, beekeepers have lost nearly 40% of their honey bee colonies. It is the highest rate reported since the survey began 13 years ago. The major cause of this downfall is colony collapse. It is a deadly trend, because of which an increasing number of honey bee colonies in the U.S. have seen the dwindling of their adult bees.
Like humans, honey bees have an ecosystem of bacteria in their guts called a microbiome. The two major causes of the colony collapse are Varroa mites and deformed wing virus. Thankfully, Scientists from The University of Texas at Austin have developed a new strategy to guard honey bees from a lethal trend known as colony collapse: genetically engineered strains of bacteria. The engineered bacteria are made to live in the gut of the bees, which act as biological factories, to synthesis medicine to protect the insects from the deadly mites and viruses. These engineered bacteria are easy to grow and easier to inoculate it into honeybees.
The bees infected with these viruses are fed upon by mites. Which then spread to the other neighbour bees, thereby infecting them with the virus. To tackle this problem the team engineered one strain of bacteria to target the virus and another for the mites. Compared with control bees, the bees treated with the strain of bacteria targeting the virus were 36.5% more likely to survive to day 10. Meanwhile, Varroa mites feeding on another set of bees treated with the mite-targeting strain of bacteria were about 70% more likely to die by day 10 than mites feeding on control bees.
The same way as humans, honeybees have their microbiome, constituting of many bacteria’s. Apart from bacteria’s, they also have an antiviral defence mechanism called RNA interference (RNAi) that helps the body fight off certain viruses, called RNA viruses. When an RNA virus is introduced, the body produces molecules called double-stranded RNAs (dsRNA’s) that a healthy cell detects, triggering an RNAi immune response.
To promote a helpful RNAi response to viruses in bees, the team introduced modified bacteria to hundreds of bees. The bees were sprayed with a sugar solution containing the modified bacteria. As a result, the team found inoculating young worker bees with the engineered bacteria led the bees’ immune systems to be primed to protect them against the deformed wing virus, which is an RNA virus, and caused the mites’ immune systems to fight against and ultimately kill them.
These experiments were conducted in strict biosafety laboratory, but the scientists have to say that even in the absence of such protocols, the risk of the engineered bacteria escaping into the wild and infecting other insects is very low. The type of bacteria used are highly specialized to live in the bee gut, can’t survive for long outside of it and are protective for a virus that strikes only bees. Another advantage of the approach is for researchers to use it as a tool in studying bee genetics.