Discovery and effects of Texas Solenopsis invicta virus [SINV-1 (TX5)] on red imported fire ant populations

Solenopsis invicta Buren (Hymenoptera: Formicidae), the red imported fire ant is native to South America but has invaded areas of the southeastern US, and parts of Southern California. The S. invicta virus-1 (SINV-1) is a positive sense, single-stranded RNA picorna-like virus that only affects Solenopsis species. The virus can infect all caste members and developmental stages. Infection of SINV-1 can result in colony collapse in less than 3 months under laboratory conditions. This study screened S. invicta colonies from Texas for the presence of SINV through Reverse Transcriptase PCR (RT-PCR). Positive samples were genetically characterized by direct sequencing and compared with known picorna-like viruses. SINV-1 was detected in ant colonies from Smith and Henderson TX counties. Amino acid sequence comparison of SINV-1 (TX5) ORF2 region showed homologies of 96% with SINV-1, 97% with SINV-1A, 17.6% with SINV-2, and 20.7% with SINV-3. In addition, SINV-1 (TX5) was compared to 18 other Dicistroviridae viruses. Ant-infecting viruses may provide new approaches to suppressing these important economic pests.