Isolation, characterization, and host specificity of Solenopsis invicta virus 6 (Cripavirus porteri), a dicistrovirus from the red imported fire ant, Solenopsis invicta.

Solenopsis invicta virus 6 (SINV-6; Cripavirus porteri) is a recently discovered dicistrovirus from the red imported fire ant, Solenopsis invicta. SINV-6 was detected in all stages of S. invicta including eggs, pupae, larvae, adult workers, male and female sexual alates, and queens. Electron microscopic examination of negatively stained samples from particles purified from SINV-6-infected fire ant workers revealed isometric particles with a mean diameter of 34.2 ± 2.1 nm. Field surveys of S. invicta nests in Alachua County, Florida, showed that the virus was present year-round. SINV-6 nest prevalence ranged from 37.5% in February to 100% in November. Among 171 nests surveyed throughout the year and over the 6-year period, 106 (62%) tested positive for SINV-6. Intra-colonial SINV-6 infection incidence and virus titer among worker ants exhibited a positive relationship. SINV-6 exhibited tissue tropism toward the abdomen where > 99% of SINV-6 was detected. Among the major tissues of the abdomen, the alimentary canal (crop, midgut, hindgut) contained 87.6% of SINV-6 with the midgut and hindgut accounting for 58.0 ± 28.7% of the total. Small quantities of SINV-6 were detected in fat body (8.4 ± 0.4%) and Malpighian tubules (4.0 ± 0.4%). SINV-6 infection did not have a significant impact on brood production in S. invicta over a 26-day period when held in the laboratory compared with uninfected control colonies. The host range of SINV-6 appears to be broad with the plus genome strand detected in six species of ants and the honey bee (Apis mellifera).