Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2023
Publication Date: 3/16/2023
Citation: Valles, S.M. 2023. Solenopsis invicta virus 3 infection alters foraging behavior in its host Solenopsis invicta. Virology. 581 : 81-88. https://doi.org/10.1016/j.virol.2023.03.003.
DOI: https://doi.org/10.1016/j.virol.2023.03.003

Interpretive Summary: The red imported fire ant was introduced into the United States in the 1930s and currently infests about 300 million acres. It causes economic losses that exceed 8 billion dollars annually in the United States and poses a threat to human health. Solenopsis invicta virus 3 (SINV-3) is a virus specific to fire ants that is an effective natural control agent for fire ants in the United States. However, the mechanism of action of the virus is not completely understood. USDA-ARS scientists at the Center for Medical, Agricultural and Veterinary Entomology (Gainesville, FL) determined that SINV-3-infection of midgut cells causes a decrease in food foraging in worker ants ultimately resulting in colony starvation. These results advance development of SINV-3 as a control agent for fire ants.

Technical Abstract: Solenopsis invicta colonies were exposed to purified preparations of Solenopsis invicta virus 3 (SINV-3) to investigate the impact of the virus infection on food retrieval behavior (foraging), brood production, fecundity, and ovary development in queens. Food retrieval by worker ants was significantly decreased in SINV-3-infected ant colonies compared with uninfected controls from day 21 to the end of the experiment at day 43. The change in food retrieval was associated with unusual behaviors exhibited by worker ants. The remaining live ant workers stuffed dead ant worker corpses into cricket carcasses (the laboratory colony food source) and they created midden piles on top of the food source. The rate at which dead worker ants were placed within the midden pile increased with time. Correspondingly, brood quantity (i.e., brood rating) among SINV-3-treated S. invicta colonies declined significantly over the duration of the test. At the end of the experiment, the mean brood rating among SINV-3-treated colonies declined to 7.5 ±3.5%, while untreated controls increased to 73.3 ±16.1%. Queen weight declined (~38%) and fecundity decreased significantly (2.5-fold) in SINV-3-infected ant colonies over the course of the experiment. Dissected ovaries from SINV-3-infected ant colonies were poorly developed and contained fewer developing ova compared with those from untreated control colonies.