Louisiana State University researchers reported on Apr. 16 that honey bees can detect viruses in their food sources and, unexpectedly, often choose to consume virus-spiked food over virus-free options.
The findings could have significant implications for understanding how diseases spread among bee populations, especially as honey bee declines linked to viral infections continue to concern scientists and agricultural producers.
Joseph McCarthy, an extension associate at the LSU AgCenter’s Entomology Department, said the initial experiment began as a simple science fair project. “We were mentoring a student through a simple experiment that was designed to see how the bees would react to viruses in their food,” McCarthy said. The team provided caged bees with two choices: sugar syrup treated with virus and syrup without any virus. Contrary to expectations, “the bees were feeding from the virus-treated syrup significantly more than the virus-free food,” McCarthy said.
Further experiments conducted at the USDA-ARS Honey Bee Breeding, Genetics & Physiology Laboratory in Baton Rouge reinforced these results. Both cage trials and field assays showed that nurse bees and foraging bees preferred diets spiked with deformed wing virus (DWV), black queen cell virus, or chronic bee paralysis virus over pure sugar solutions or water. Paula Castillo Bravo, an LSU AgCenter entomology researcher and extension agent who co-authored the study, explained that protein levels in viral extracts were too low for attraction: “We wanted to evaluate if the bees were attracted to possible proteins present in viral exacts from sick bees; but at the end, we determined that the amount of proteins were very low, near to undetectable levels for the bees.”
McCarthy described this as a unique discovery: “To our knowledge, this is the first indication that honey bees, or any insect, can directly detect and respond to viruses outside of a host organism.” The reason behind this behavior remains unclear. One theory suggests certain viruses may manipulate bee behavior much like other pathogens do with their hosts.
Despite widespread infection rates among bee colonies—especially with DWV—the mechanisms by which honey bees sense these viruses are not fully understood since viruses do not produce odorants like bacteria or fungi. “There are still a lot of questions that we are excited to investigate,” McCarthy said.
The research team emphasized potential broader impacts of their findings on epidemiology within bee populations and possibly even on understanding similar detection mechanisms across biological systems. As McCarthy concluded: “We found evidence that honey bees directly detected viruses within contaminated food sources, which in turn influenced their feeding and foraging behaviors.”
Future research will focus on uncovering how this detection occurs—and why it leads honey bees toward rather than away from infected sources.