Effect of Solenopsis invicta virus 3 on brood mortality and egg hatch in Solenopsis invicta

Authors: Valles, Steven

Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/31/2023
Publication Date: 1/3/2024
Citation: Valles, S.M. 2024. Effect of Solenopsis invicta virus 3 on brood mortality and egg hatch in Solenopsis invicta. Journal of Invertebrate Pathology. 203. https://doi.org/10.1016/j.jip.2023.108056.
DOI: https://doi.org/10.1016/j.jip.2023.108056

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 can be transmitted from immature stages to adults. Furthermore, it was found that adult care behavior is unaffected by the virus infection. These results advance the understanding and development of SINV-3 as a natural control agent for fire ants.

Technical Abstract: Solenopsis invicta virus 3 has been shown to cause significant mortality among all stages of its host, Solenopsis invicta. One impact of the virus is alteration of worker ant foraging behavior, which results in colony starvation and collapse over time. Additionally, it has been hypothesized that SINV-3 infection of S. invicta may disrupt worker ant brood care behavior. To investigate this possibility, various combinations of SINV-3-infected and -uninfected adult (worker) and immature (brood) stages were placed together and monitored using the response variables, mortality, egg hatch, and virus load. Significant differences in percent cumulative S. invicta worker ant mortality among six combinations of SINV-3-infected and -uninfected stages were observed. In contrast, no significant differences in percent cumulative mortality of S. invicta larvae or pupae were observed among the four different combinations of SINV-3-infected and -uninfected groups by the end of the study (day 35). No significant differences in egg hatch were observed between SINV-3-uninfected, SINV-3-infected (colony-treated and queen-treated), and starved colonies. Eggs hatched normally in 10-12 days for all treatments indicating that egg care by worker ants was unaffected by SINV-3 infection status. The study further clarifies SINV-3 pathogenesis in its host, S. invicta. Larval mortality in SINV-3-infected colonies does not appear to be caused by worker ant neglect. S. invicta larvae under the care of SINV-3-infected worker ants did not exhibit higher mortality rates compared with those tended by SINV-3-uninfected worker ants.