Global trade is the number one avenue for stowaway pests. Along with goods, the United States alone has inadvertently imported kudzu, zebra mussels, hemlock woolly adelgids, and emerald ash borers—exotic plants and animals that have smothered, choked, poisoned, and eaten through our native ecosystems. We’ve also intentionally brought in mongooses, boa constrictors, wild hogs, and starlings. Such heavy appetites for goods from abroad, and the means to afford them, has led to invasive species often being considered a “first-world problem.”
But not for much longer. A study published on August 23 in Nature Communications estimates that in the 21st century, the developing world will see a rise in invasive species, an issue most of these countries are neither equipped to prevent nor stable enough to endure.
We’re not just talking about a bunch of stinkbugs buzzing around the third world’s lightbulbs. We’re talking about species like prosopis, a thorny mesquite shrub from Central and South America that invaded Ethiopia in the 1970s and has since spread out over more than 1.7 million acres of the country’s choicest grazing lands. The mesquite pushes out the plants cattle typically graze on, poisons anything that dares eat it (human and bovine alike), and slurps up the water supply with its roots.
“As a result, many thousands of people are losing their livelihoods, having to leave their land, and going hungry,” says the study’s lead author, Regan Early, an ecologist at the University of Exeter. “Locals call it the devil tree.”
Globalization is part of the reason why the developing world is primed for biological invasion. The far-flung corners of the world are becoming increasingly connected through tourism, trade, and improving infrastructure. So it was only a matter of time before these nations felt the sting of nettles or, say, the chokehold of kudzu.
According to researchers, several factors contribute to a region’s vulnerability. Some are fairly obvious—how many plants and animals are imported each year or the number of seaports and airports in the region. Between 1984 and 2000, 73 percent of recorded pest interceptions in the United States occurred at airports, says Early, with 62 percent of those fugitives found in peoples’ baggage.
More abstract variables include the rate of agricultural expansion in an area and its risk of forest fires. Any disruption to a landscape, you see, makes its ecosystem more vulnerable to colonization by invaders. For instance, when a wildfire burns up an area’s grasses, shrubs, and small trees, it makes room for opportunistic interlopers. The same thing happens when farmers and ranchers convert natural habitat into cropland and pasture. By altering the structure of native ecological communities, these activities, in a way, welcome new species to settle in while the natural order is in upheaval.
Early and her coauthors analyzed the invasion threat for every landmass on earth (except Antarctica and the parts of Greenland covered in glaciers). They found that roughly one-sixth of the planet’s land surface is highly vulnerable to invasion. Furthermore, 16 percent of the world’s biodiversity hot spots are at high risk, such as the western and central Himalayas and the grasslands, forests, and highlands of Lesotho. These vulnerable areas also overlap with the less developed parts of Africa, South America, and Asia. In fact, Early found that around 15 percent of the land in low-income countries faces an elevated threat.
The real problem isn’t so much the third world’s vulnerability but its ability to fight back. Countries like the United States have huge government programs and departments to identify potential invasives even before they enter the country and to combat them if they find their way in. “The resources of low-income countries are already hugely overstretched,” Early says, “so having even a small proportion of their land surface highly threatened by invasions is a serious concern.”
In 2015 the U.S. Department of Agriculture’s anti-invasive program (called the Animal and Plant Health Inspection Service, or APHIS) spent $20 million to eradicate feral hogs, but not from the country at large. No, no. The $20 million was enough to remove that single invasive species from only 4 out of the 39 states the pigs were thought to infest.
Hogs, at least, are unlikely to travel across borders on the bottom of a shoe or in someone’s carry-on. The same cannot be said for pests so small that they can stow away in a piece of fruit or among the packing materials of internationally shipped goods. Air travel is particularly dangerous because it allows fragile species like the Mediterranean fruit fly to survive long trips to a new territory, as it did when it came to the United States early last century.
Species invasions are especially scary for developing nations due to the fragility of some of their economies and food production systems, which would be more likely to collapse under excess strain than would those of more stable countries.
Since such pests can be prohibitively expensive to eradicate once they’ve set up shop, Early and her coauthors recommend acting fast by first making a list of all known species likely to colonize an area. After all, identification is critical during the early stages of an invasion. Currently, Early and her colleagues at the Centre for Agriculture and Biosciences International are working to determine what could be the next troublesome critters for Malawi, Tanzania, and Uganda.
Beefing up border-customs policies, investing in research programs, developing early-warning systems, and educating farmers, ranchers, rangers, and others who might first notice an invasion taking hold could also potentially help neutralize pests before they take over. The rest of the world could also lend a hand by sharing data and collaborating on the research and training that developing countries can’t afford—a good strategy, since one country’s invasive species can soon become another’s.
All this will cost some serious time and money, but a plague of locusts (or devil trees, for that matter) can devastate a poor community’s food or economic base. Like any other natural disaster, prevention and response will be worth the investment.
onEarth provides reporting and analysis about environmental science, policy, and culture. All opinions expressed are those of the authors and do not necessarily reflect the policies or positions of NRDC. Learn more or follow us on Facebook and Twitter.
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