When viral infection meets sociobiology: RNA virus dynamics in field Argentine ant populations

Interactions between host and pathogen represent a main factor that shapes pathogen dynamics in
a host population. Here we present the result of 2-year (2019-2020) viral surveillance in two field
populations of Argentine ant (Linepithema humile) in Japan and discuss potential sociobiological
factors for the observed seasonal viral dynamics. We monitored the viral infection status of
foraging workers attracted to lure stations, which consists of carbohydrate and protein-rich
recourses that were on separate containers, once every month. The viruses surveyed for included
several previously reported RNA viruses (LHUV-1, LHuPcV1, LHuCV1, LHuPiLV1, and
LHuNLV1). The results showed that LHUV-1 has been among the most dominant virus across
the 2-year period and possessed strong seasonality, with higher infection rate among foraging
workers during the cold months but lower entering the spring. LHUV-1 was found to be more
prevalent in foragers from one population than the other, however, the proportion of infected
workers was higher on protein lure compared to carbohydrate lure regardless of the population
origin. This suggests LHUV-1 infection interacts with the ant’s foraging behavior. Potential
sociobiological factors (e.g., supercolony structure, regulation of colony organization and
nutritional compensation) affecting the viral infection pattern will be further discussed.