Highly competent native snake hosts extend the range of an introduced parasite beyond its invasive Burmese python host

Invasive Burmese pythons (Python bivittatus ) have introduced a nonnative pentastomid parasite (Raillietiella orientalis ) to southern Florida that has spilled over to infect native snakes. However, the extent of spillover, regarding prevalence and intensity, is unknown. We examined native snakes (n  = 523) and invasive pythons (n  = 1003) collected from Florida to determine the degree to which parasite spillover is occurring. We found R. orientalis has infected 13 species of native snakes collected from areas of sympatry with pythons. Prevalence and infection intensity of R. orientalis were significantly higher among native snakes compared with pythons. Moreover, adult female pentastomes achieved larger sizes and represented a greater proportion of the overall parasite population in native snakes vs. pythons, indicating native snakes are more competent hosts of R. orientalis than pythons. We also examined native snakes from regions of allopatry with pythons to determine how far R. orientalis has spread. We found an infected native snake 348 km north of the northernmost infected python. Our data show that native snakes are highly competent hosts of R. orientalis and have facilitated the rapid spread of this nonnative pentastome beyond the range of its invasive host.