Dynamics of Israeli acute paralysis virus in the red imported fire ant (Solenopsis invicta Buren) colonies

The red imported fire ant, Solenopsis invicta Buren, is one of the most significant pest ants in the southern United States, frequently found in honey bee colonies and their surrounding areas. While fire ants scavenge on dead bees and may function as secondary hosts or reservoirs for several honey bee-associated viruses, evidence of viral dynamics and persistence in fire ant colonies has been inconclusive. In this study, we conducted a series of experiments to test the possibility of food-borne virus transmission i.e. horizontal transmission from virus-infected honey bee pupae to fire ants and persistence of the virus within the fire ants' colonies. Israeli acute paralysis virus (IAPV) was used as an experimental pathogen due to its relevance to honey bee health and its limited prevalence. Our results showed that fire ants can acquire IAPV horizontally by consuming virus-infected honey bees. The virus may spread rapidly across all developmental stages (larvae, pupae, and workers) within the colony, likely facilitated by the social interactions. Additionally, fire ant queens can likely acquire the virus via trophallaxis and/or physical contact with workers. Our results further indicated that IAPV could be transmitted vertically, however confirmatory research is required. Monitoring the virus after 4 months of inoculation confirmed that a significant IAPV load persists in all developmental stages of colony members. These findings suggest that fire ants can act as virus reservoirs for a deadly honey bee-associated virus, posing a potential threat to the health and well-being of bee pollinators.