Life-Sucking Parasites Can Help Save Species

Doing what's in the best interest of an endangered species means supporting the parasites that can do the animals harm.

Doing what's in the best interest of an endangered species means supporting the parasites that can do the animals harm, according to a new study in Trends in Ecology and Evolution.

In an effort to protect endangered species, specifically those brought up in captive-rearing programs, conservation experts often do their best to ensure a healthy, parasite-free environment. A parasitic infection not only weakens a single animal but could spread through an entire population.

While the idea of preserving parasites no doubt appears to betray the idea of supporting an endangered species, despite the risk of illness or even death, parasites can provide critical long-term immunological benefits that are key to a species' survival.

Top 10 Insects, Spiders and Bugs: Photos

"Exposure to parasites in early life can confer improved resistance to the same parasites later on," said Hamish Spencer of the University of Otago in New Zealand, "and recent research shows that such exposure may enhance the overall development and efficacy of the immune system in defending against a wide variety of infections."

The loss of these parasites threatens the long-term survival of endangered species, particularly with any efforts to reintroduce them into a natural habitat. As much as they may threaten an individual's health, parasites play an important ecological role.

According to a 2011 study published in Biological Conservation, parasitism is the most common life strategy on Earth. "t least 76,000 parasitic species inhabit the nearly 45,000 species of described vertebrate hosts," the authors write. Ignoring such a major player within any ecosystem threatens the success of other species with which the parasites coevolved.

The evolution of the relationship between a parasite and its host over time also has implications for whole networks of species. In the same way that the food web transfers energy across species and affects animal populations, the integration of parasites and host animals within the same ecosystem affects growth, reproduction and long-term survival.

Parasites May Fuel Cannibalism in Many Animals

Removing parasite exposure entirely carries with it the risk of leaving a population more susceptible to other diseases and conditions. In humans, for example, asthma, allergies, a number of other inflammatory diseases and other autoimmune ailments have all been connected by various studies to the parasite-free existence common in modern industrialized nations.

In fact, helminthic therapy is an experimental type of treatment in which sufferers of certain autoimmune disorders are deliberately infected with parasites. The treatment isn't without risks, as patients potentially face the kinds of symptoms typical of a parasitic infection.

Parasites are gross. There's no denying that. They can suck blood, spread disease, make a home in another organism's body and even kill. But saving endangered species and conserving vulnerable ecosystems also means protecting the parasites that we'd otherwise prefer to eradicate.

Video: How Worms Can Fix Your Heart

Insects and other creepy crawlies may be tiny, but their lineages are mighty, finds a new study that determined the common ancestor of mites and insects existed about 570 million years ago. The study, published in the latest issue of the journal Science, presents an evolutionary timeline that settles many longstanding uncertainties about insects and related species. It found that true insects first emerged about 479 million years ago, long before dinosaurs first walked the Earth. Co-author Karl Kjer, a Rutgers entomologist, explained that mites are arthropods, a group that's distantly related to insects. Spiders and crustaceans are also arthropods.

50-Million-Year-Old Mite Chomps Into Ant's Head

Spiders such as the huntsman spider can, like mites, trace their lineages back to about 570 million years ago, according to the new study. The researchers believe that the common ancestor of mites, spiders and insects was a water-dweller.

Photos: Giant Spiders to Freak You Out

Millipedes, such as the one shown here, as well as centipedes are known as myriapods. The most recent common ancestor of myriapods and crustaceans lived about 550 million years ago. Again, this "mother of many bugs" would have been a marine dweller. Kjer explained, "You can't really expect anything to live on land without plants, and plants and insects colonized land at about the same time, around 480 million years ago. So any date before that is a sea creature." Moving forward in time, the most common ancestor of millipedes and centipedes existed a little over 400 million years ago. The leggy body plan has proven to be extremely successful.

Leggiest Animal Thrives Near Silicon Valley

"This is an early insect that evolved before insects had wings," Kjer said. Its ancestry goes back about 420 million years. The common ancestor of silverfish living today first emerged about 250 million years ago. Dinosaurs and the earliest mammals likely would have then seen silverfish very similar to the ones that are alive now.

Photos: Faces of Bees, Flies and Friends

Dragonflies and damselflies have family histories that go back about 406 million years. Kjer said that such insects looked differently then, however. "For example," he said, "they had visible antennae." Their distant ancestors were among the first animals on earth to fly.

Dragonfly Drone Takes Flight

"Parasitic lice are interesting, because they probably needed either feathers or fur," Kjer said. As a result, they are the relative newbies to this list. Nonetheless, the researchers believe it is possible that ancestors of today's lice were around 120 million years ago, possibly living off of dinosaurs and other creatures then.

10 Worst Epidemics

Crickets, katydids and grasshoppers had a common ancestor that lived just over 200 million years ago, and a stem lineage that goes back even further to 248 million years ago. A trivia question might be: Which came first, these insects or grass? The insects predate the grass that they now often thrive in.

Nightmarish Cricket That Eats Anything Is Now Invading the US

Dinosaur Era fossils sometimes include what researchers call "roachoids," or wing impressions that were made by ancestors to today's roaches, mantids (like the praying mantis) and termites. "Some cockroaches are actually more closely related to termites than they are to other cockroaches," Kjer said, explaining that this makes tracing back their lineages somewhat confusing. He and his colleagues determined that the stem lineage goes back about 230 million years, while the earliest actual cockroach first emerged around 170 million years ago.

Cockroaches: The Ultimate Survivors

Termites and cockroaches have a tightly interwoven family history. Termites similar to the ones we know today were around 138 million years ago. Now we often think of termites as pests, but they are good eats for many different animals, which back in the day would have included our primate ancestors.

Flies like houseflies that often buzz around homes belong to the order Diptera, which has a family tree that goes back 243 million years ago. The most recent common ancestor for modern flies lived about 158 million years ago, according to the study. There is little doubt that the earliest humans, and their primate predecessors, had to contend with pesky flies and all of the other insects mentioned on this list. All of these organisms are extremely hardy. The researchers determined that, in the history of our planet, there has only been one mass extinction event that had much impact on insects. It occurred 252 million years ago (the Permian mass extinction), and even it set the stage for the emergence of flies, cockroaches, termites and numerous other creepy crawlies.

That Beer Smell? Designed to Attract Flies