Invasive Species Are Afflicting the Most Vulnerable Countries

Globalization and international travel are spreading pests and pathogens that can devastate agricultural economies.

The Asian long-horned beetle threatens Canada’s hardwood forests. (Photo: Dick Loek/‘Toronto Star’ via Getty Images)

Jun 20, 2016· 3 MIN READ
Richard Conniff is the author of House of Lost Worlds: Dinosaurs, Dynasties, and the Story of Life on Earth and other books.

In the summer of 1996, a Brooklyn developer named Ingram S. Carner noticed that the sugar maples in his neighborhood were struggling and also had unusual holes in their trunks. Carner suspected a vandal armed with a portable drill. He staked out the scene, and after a long wait, something far more dangerous crawled out of one of the holes: a beetle.

“He could have looked at it and paid no attention. He could have stepped on it,” said Richard Hoebeke, an entomologist then working at Cornell University. Instead, the specimen soon found its way to Hoebeke’s desk. “It was nothing I had ever seen before, clearly nonnative,” he said. But within a few hours, he was able to pronounce it an Asian long-horned beetle (or rather, Anoplophora glabripennis), the first to be identified in this country.

If it had gone undetected, a study by the U.S. Forest Service later estimated, the beetle could have killed a third of the trees in cities nationwide, at a loss of up to $669 billion. Instead, the discovery launched a major campaign to locate and contain the invasion at a handful of sites around the United States.

Here’s the scary thing: Invasions like that happen all the time. Roughly 50,000 alien species are established in the U.S., and a 2005 study put the economic and environmental costs at $120 billion a year. Most of that is in damage to agricultural crops and forests. But take a look at the plants and animals on the threatened and endangered species lists, for instance, and invasive species are the main reason about 42 percent of them are in trouble.

Scarier still, globalization of trade and increasing international travel make the danger worse each year. A new study in the journal Proceedings of the National Academy of Sciences has added up the factors determining whether a species invades another country and becomes established well enough to do serious damage. It found that China and the United States are the countries at greatest risk, in purely economic terms. That’s mainly because those two countries lead the world in international trade. For the same reason, they are also the leading sources of species likely to become invasive elsewhere.

But this all sounds a little abstract. So let’s look at a recent case study. Sometime in the 1980s, a trivial-seeming species called the spiny water flea invaded the Great Lakes and spread from there. Lake Mendota in Madison, Wisconsin, in particular, seems to have been spiny water flea heaven. Since spiny water fleas are enthusiastic predators, they demolished the population of a native species called Daphnia pulicaria. The Daphnia in turn are enthusiastic grazers, and when they disappeared, weedy vegetation boomed, turning formerly clear water murky. This is what scientists call a trophic cascade. Nonscientists just say, “What the hell happened to my lake?”

The good news, Madison, is that you can get your lake back. But since you’re now stuck with the spiny water fleas, the only practical way to do it is to get rid of the pollution that’s feeding all that vegetation. To be precise, it’s going to require a 71 percent reduction in the amount of phosphorous entering the lake from farms, lawns, and household plumbing, at a cost somewhere between $87 million to $163 million. (After that, we can talk about Lake Monona, just next door.) Multiply the mess in Madison by 10,000 or 100,000 other lakes, plus countless rivers, fields, and forests, and you may begin to see why it’s a big deal when alien species slip into the country.

What can we do to minimize the risk? The first step is to stop being stupid. We live in a time of mindless demagoguery about the dangers of “big government” combined with an irrational drive to cut all federal funding across the board (except for the military), regardless of the demonstrable benefits. So who is going to do proper inspections at ports and airports if not U.S. Customs and Border Protection? Who will make difficult taxonomic identifications fast enough to block invasive species at the border, other than the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service? This is one of the many reasons we have a federal government.

So call it “defense funding” if you must. Or call it “standing up to China” when federal agents turn a ship around and order it back to its point of origin because it’s infested with Asian gypsy moths. Just accept that our taxes sometimes work to our joint benefit, and get on the phone to tell your representatives in Congress to fund these watchdogs at our borders.

Since we’re also big on talking about “individual responsibility” these days, it’s worth noting that individuals can make a difference too by paying attention to the rules on what you can legally bring back from travel abroad. When the customs agent confiscates the specialty meat you were trying to sneak into the country, that’s not government tyranny in action. It’s not even government tyranny when the law prevents you from carrying firewood across state lines. Instead, these are measures to prevent invasive species and pathogens from getting into the country in the first place and spreading once they get here.

One last point about the new study in PNAS. The authors don’t make a big deal of it, but there’s a poignant dark side to the international trade–invasive species equation: When you look at the potential damage to the quality of life—and not just at dollars and cents—the countries that benefit least from international trade seem nonetheless to suffer the worst risks. Countries in sub-Saharan Africa in particular tend to lack diverse economies and depend largely on agriculture, leaving them highly vulnerable to invasion by agricultural pests and pathogens. For us, the risk is about economic loss. For them, it’s about not being able to feed their families. It’s a lot like what’s happening with the consequences of climate change: Those least to blame nonetheless face the biggest potential hit.

That’s a hidden cost researchers and political analysts should be taking into account when they talk about the value of international trade.