Deformed wing virus detected in invasive fire ants

Scientists with the U.S. Department of Agriculture’s Agriculture Research Service (USDA ARS) and Mississippi State University may be one step closer to understanding how deformed wing virus (DWV), a pathogen that has been linked to colony collapse disorder (CCD) in honey bees (Apis mellifera), is spread.

DWV is a serious pathogen found throughout the world that can affect many different insects, including honey bees. The virus is transmitted to honey bees by the Varroa mite, an external parasite of honey bees, causing physical and behavioral impairments that can shorten the bees’ lifespan.

Researchers detected DWV in colonies of both red imported fire ants (Solenopsis invicta) and black imported fire ants (S. richteri) in Mississippi. They were able to confirm that the virus is replicating in both species, and DWV-like symptoms were observed in infected laboratory and field colonies of both species. Researchers have not yet linked the cause of the symptoms to the virus.

These findings could point to red and black imported fire ants serving as hosts of DWV, and that both species may even serve as a source of infection for honey bees. This would be concerning for beekeepers, given the expansive range distribution of both ant species throughout much of the southern United States. The researchers are quick to point out, however, there are several questions left to answer before those details can be confirmed.

For starters, how are the fire ants becoming infected? Are fire ants feeding on infected honey bees and acquiring the virus that way? Or are they picking up the virus from shared food sources that both bees and fire ants frequent, such as flowers and other nectar sources? Most importantly, we know fire ants can become infected with the virus, but can they shed the virus to infect honey bees?

Dr. Bentley is VP of training and technical services for the National Pest Management Association. You can reach him at mbentley@pestworld.org.