Protecting Bees from the Inside Out

A Varroa mite, a common pest that can weaken bees and make them more susceptible to pathogens, feeds on a honey bee. Credit: Alexander L. Wild

Pollinating $20 billion of crops each year, honey bees are important to our economy and food supply. They also are in crisis. A national survey estimated that beekeepers lost 37% of their colonies over the 2018–2019 winter, and 22% the following winter. Most often, a type of parasitic mite and a virus that the mites help to spread are the culprits.

UT Austin researchers, including professors Nancy Moran and Jeffrey Barrick, and postdoctoral fellow Sean Leonard, have engineered strains of bacteria to help defend bees against these pathogens. For each threat — Varroa mites and deformed wing virus — the scientists engineered bacteria that live in the guts of honey bees to act as biological factories, pumping out protective medicines.

The engineered bacteria act as double-agents to destroy Varroa mites. First, the bees ingest the bacteria, which enters their gut. Second, the mites that feed on the bees’ blood in turn ingest products made by the engineered cells. Finally, the ingested molecules trigger an autoimmune response within the mite — turning the intruder’s defenses against itself. The parasitic invasion ends in a life-saving self-destruct.

The second strain of engineered bacteria works differently to disable the deformed wing virus. The bacteria primes the bees’ immune defense mechanisms, much like a vaccine, so it can target and destroy an incidence of foreign, virus-causing RNA.

While still untested in larger, real-life agricultural settings, the researchers suggest that this bee-saving technology could make the jump from lab to crop without much difficulty. And as Leonard points out, the result represents a big step forward in biology: “It’s the first time anyone has improved the health of bees by genetically engineering their microbiome.”