Virome of Solenopsis invicta (Hymenoptera: Formicidae): Intercontinental differences in the native and introduced ranges

A comprehensive survey of 430 Solenopsis invicta nests from 82 different sites in Argentina and the USA was conducted for all currently known viruses infecting, or associated with, the invasive red imported fire ant, S. invicta. Comparisons in viral abundance, diversity, and possible social form preferences were made. Monogyny was the more prevalent S. invicta colony social form detected on both continents. Seventeen of the twenty (i.e., 85%) known viruses associated with S. invicta were observed in Argentina, compared with 11 (55%) viruses detected in S. invicta in the USA. Two viruses, Solenopsis invicta virus-16 (SINV-16) and SINV-17, were not detected on either continent. Seven viruses, SINV-5, SINV-8, SINV-10, SINV-11, SINV-12, SINV-13, and Solenopsis invicta densovirus, were unique to Argentinean S. invicta (i.e., only detected in Argentina) and one virus, SINV-14, was unique to USA S. invicta. The mean number of viruses per nest was significantly (5.4-fold) greater in S. invicta from Argentina compared with S. invicta from the USA. Greater viral diversity and abundance in the native range, Argentina, compared with the introduced range, USA, supports the “enemy release hypothesis” to explain the disparity in S. invicta population levels and pest intensity between the two continents.