Field host range of the fire ant pathogens Thelohania solenopsae (Microsporida: Thelohaniidae) and Vairimorpha invictae (Microsporida: Burenellidae) in South America

Abstract

We studied the field host specificity of the microsporidia Thelohania solenopsae and Vairimorpha invictae and their prevalence in the imported fire ants, Solenopsis invicta and S. richteri. Terrestrial ants were sampled by using bait traps and/or nest sampling at preselected sites in Argentina and Brazil. The sampling included the genera Solenopsis, Pheidole, Camponotus, Crematogaster, Linepithema, Brachymyrmex, Paratrechina, Dorymyrmex, and Wasmannia. The samples were examined under a phase-contrast microscope for the presence of microsporidian infections. The bait trap sampling revealed that: (1) T. solenopsae infected only S. richteri, S. invicta, and Solenopsis sp. at 6-67% of the sites and in 1.5-29% of the traps; (2) V. invictae infected only S. invicta at 6% of the sites and in 3% of the samples. The nest sampling revealed that: (1) T. solenopsae infected S. invicta, S. richteri, and S. macdonaghi, at 41-67% of the sites and in 11-58% of the colonies; (2) V. invictae infected the same species at 15-50% of the sites and in 2-26% of the colonies. We detected T. solenopsae and V. invictae in equal percentages of S. invicta sites (41%); however, the percentage of colonies infected with V. invictae was 20% and with T. solenopsae only 11%. At S. richteri sites, in contrast, T. solenopsae occurred at 46% of the sites and 15% of the colonies and V. invictae occurred at only 15% of the sites and 2% of the colonies. In S. macdonaghi, T. solenopsae was detected at 67% of the sites and 58% of the colonies, and V. invictae was detected at 50% of the sites and 26% of the colonies. This is the first report of V. invictae infecting S. macdonaghi. The proportion of S. richteri and S. invicta infected with T. solenopsae was similar. In contrast, the proportion of S. invicta infected with V. invictae was higher than S. richteri. We conclude that the microsporidia, T. solenopsae and V. invictae, show a very high specificity for Solenopsis ants in the field. It appears that T. solenopsae infects S. invicta and S. richteri equally but V. invictae may be more adapted to infect S. invicta. Published by Elsevier Science (USA).

Natural Occurrence and Laboratory Studies of the Fire Ant PathogenVairimorpha invictae(Microsporida: Burenellidae) in Argentina

“…These authors found V. invictae and T. solenopsae on several occasions infesting the same sites, mostly S. richteri sites, but never infecting the same colonies. Dual infections appear to be more common in S. invicta sites because V. invictae was more frequent in S. invicta than in S. richteri (Briano et al 2002).…”

“…It was later recovered from other species of Þre ants such as S. richteri Forel (Jouvenaz et al 1980, Wojcik et al 1987, Briano et al 1995b) and S. macdonaghi Santschi (Briano et al 2002) in Argentina. V. invictae is an obligate, intracellular, and dimorphic microorganism that produces distinct mononucleate meiospores and binucleate spores that develop sequentially in larvae, pupae, workers, sexuals, and queens.…”

Effect of mono- and polygyne social forms on transmission and spread of a microsporidium in fire ant populations

“…Thelohania solenopsae also has been found in the congenerics, Solenopsis richteri (Allen and SilveiraGuido, 1974), S. saevissima, S. quinquecuspis, S. macdonaghi, and S. blumi [D S. quinquecuspis] (Allen and Knell, 1980). However, infections were not detected in nine other nonSolenopsis genera of ants (Williams et al, 1998;Briano et al, 2002). It was noted that T. solenopsae-infected Weld colonies of Solenopsis spp.…”

Molecular diversity of the microsporidium Kneallhazia solenopsae reveals an expanded host range among fire ants in North America

“…K. solenopsae spores have been detected microscopically in the black fire ant, Solenopsis richteri, in South America (Allen and Silveira-Guido, 1974;Briano et al, 1995), in other Solenopsis species from Brazil (Allen and Buren, 1974), and in Solenopsis daguerrei, a social parasite of fire ants (Briano et al, 1996). K. solenopsae spores were not found in other ant genera in South America (Briano et al, 2002), suggesting that the host range of K. solenopsae is restricted to the genus Solenopsis. An extensive survey for fire ant pathogens was conducted in the mid 1970s in the USA (Jouvenaz et al, 1977).…”