Rapid Geographic Spread of Invasive Pentastome Parasites in Pygmy Rattlesnakes (Sistrurus miliarius)

Farrell, Terence M. tfarrell@stetson.edu

Department of Biology

Stetson University

DeLand, Florida USA

Parasite spillover, the spread of nonindigenous parasites to native species, can be an important impact of nonnative species. Raillietiella orientalis, an Asian pentastome (endoparasitic crustacean), was introduced in south Florida with Burmese Pythons (Python bivittatus). This parasite has spread to native snakes. From August 2018 to February 2019, we found R. orientalis in Pygmy Rattlesnakes (Sistrurus miliarius) in central Florida, more than 160 km north of this parasite’s published geographic range. In winter 2019, we examined 34 S. miliarius using dissection, endoscopy, lung washes, or cloacal washes to determine the prevalence of R. orientalis at two central Florida locations that were separated by 34 km. There was a significant difference between the two sites in pentastome prevalence, with 65.9% and 8.3% of all S. miliarius infected at the northern and southern sites, respectively. The parasites appear to have major negative health consequences in S. miliarius, including causing mortality. The mean length of the adult female parasites removed from the lungs of Pygmy Rattlesnake (59.0 mm) and the mean number of adult females (3.1 individuals/snake) were both greater than that reported in published records for Burmese Pythons, a species with which R. orientalis shares a coevolutionary history. Heavy pentastome loads often coincide with snake fungal disease, both may be energy drains on the hosts, and snakes with both issues are often emaciated. The impact of this invasive parasite on native snake populations will be a function of a variety of unknown aspects of its biology, including its rate of spread, identity of the intermediate hosts consumed by snakes, and the extent of lethal and sublethal effects of pentastome infection on host fitness.