Invasive ants are considered among some of the most destructive biological invaders and have been reported to dramatically reduce native ant biodiversity. Among the world’s most notorious invasive species is the little tropical fire ant Wasmannia auropunctata, which in recent decades has emerged as a global agricultural pest causing significant economic damage and reductions in crop yields and posing as a health nuisance. The enemy release hypothesis (ERH) posits that invasive species get released from natural enemies, including parasites, during introductions into novel habitats. Despite the high invasive success of ants, suprisingly little is known about the degree to which their success can be attributed to release from parasites.We assessed the diversity, prevalence, and virulence of entomopathogenic fungi in W. auropunctata populations found in the native range of Mexico and introduced range of Puerto Rico. The diversity of fungal entomopathogens was determined through direct sequencing. We examined differences in the frequency of generalist pathogen found in W. auropunctata populations through molecular typing. Lastly, we assessed the virulence of generalist pathogens through innoculation experiments.
Results/Conclusions
We detected a total of 12 fungal species mainly belonging to the genera Metharizium and Beauvaria. The vast majority of fungal entomopathogens were found in the native range of W. auropuncta. A systematic search for the presence of the four common generalist fungal entomopathogens revealed large variations in their prevalence. Innoculation experiments by the four generalist pathogens caused significant mortality in W. auropunctata populations, but varied in their degree of virulence. Overall, our study shows that W. auropunctata populations encounter a diversity of fungal entomopathogens in their native range of Mexico. Furthermore, we found that some generalist pathogens vary in their prevalence and virulence in W. auropunctata populations. The low diversity and prevalence of fungal entomopathogens found in W. auropunctata populations within the introduced range of Puerto Rico might explain the astounding success of this invasive species.