Invasive Burmese pythons have become the ravenous, ever-multiplying scourge of South Florida. But new research suggests that the snakes have brought more than just their teeth and appetites to the Sunshine State. They’ve also brought along their own parasites, which are now infecting native snakes.
Burmese pythons have been getting plenty of well-deserved attention for their ecological takeover in Florida. The pythons are native to Southeast Asia, but are now established in South Florida’s wilds as a foreign invader, likely thanks to the exotic pet trade. The Burmese python invasion has been particularly unnerving in conservation circles because the nearly 20 foot-long predators are eating their way through the wetlands’ wildlife, which is having ripple effects that are reshaping entire ecosystems.
Voracious appetites aside, research published this week in the journal Ecology and Evolution suggests that the pythons are also having a more subtle and nefarious effect on native wildlife. Burmese pythons harbor non-native parasites in their lungs, and these parasites are now showing up inside of native snakes. By introducing new parasitic disease sources into Floridian ecosystems, the pythons may be harming native snake populations in ways that could stick around for a long time.
The team of researchers behind the new study—made up of scientists at Auburn University, the University of Florida, Everglades National Park, and the United States Geological Survey—collected hundreds of dead invasive pythons and native snakes from either salvaged roadkill, or pythons euthanized as part of the Everglades National Park’s ongoing removal program. There’s plenty of native snake diversity in South Florida to go around; in just the boundaries of the Everglades, there are 25 native snake species, including the gorgeous, federally threatened eastern indigo snake.
The team then examined the snakes for lung parasites, dissecting them in search of “pentastomes.” While worm-like in appearance, these parasites are actually weird crustaceans that have dramatically reduced their body parts for a life spent on the dole. Pentastomes can infect all vertebrate groups, but the majority use reptiles as their “definitive” host—the host that supports the mature, reproductive form of a parasite. Pentastome infection can be pretty nasty, causing pneumonia or sepsis from the growing parasite’s molted skins rotting inside the lungs. Even in less severe cases, pentastome knots can block up the lungs, making breathing difficult.
To reliably identify the pentastomes, the team sequenced sections of their genetic code that function as a “barcode.” By comparing these barcodes with those in a database, the scientists identified the species of each pentastome, and determined the degree of relatedness between all the pentastomes they found.
Of the three species of pentastomes found in the native snakes, two were also found in the Burmese pythons: Raillietiela orientalis and Porocephalus crotali. Based on the genetics, the researchers found that the Raillietiela species originally came from the pythons, and has spread into many native snake species. Porocephalus crotali, on the contrary, is native to the U.S., and until now, it’s only been found in vipers like rattlesnakes and copperheads. Turning up inside the invasive pythons shows that parasite transfer has gone in the opposite direction, too (called “parasite spillback”).
The future ecological and conservation impacts of this pentastome pandemonium are unclear. The sheer diversity of native snakes infected with the introduced Raillietiela—nine different species already—is unsettling for conservation, since we don’t know how certain snakes will cope with the stresses of the unfamiliar parasite.
The pythons can also act as a massive reservoir for the native Porocephalus pentastomes, which might drive increased infection among native vipers. This could be bad news for species like the eastern diamondback rattlesnake—North America’s largest venomous snake—which has already suffered steep population declines in recent decades.
Whatever happens, the findings illustrate the multifaceted nature of how invasive species can screw with ecosystems. As for the Burmese python, the study provides those valiantly attempting to eradicate the species from South Florida with an even clearer vision of what may be at stake.