The Real Threat on the Border

You may not think of Portal, North Dakota, a town of 120 people on the Canadian border, as a key link in national defense. But late last month, United States Customs and Border Protection agents there boarded a freight train entering the country and found six carloads contaminated with invasive insects and seeds from China and Southeast Asia. They were the kind of invasive species that demolish crops, destroy people’s livelihoods, and displace indigenous wildlife.

The government sealed three carloads and sent them back to Asia, releasing three others to the owners after decontamination. It was a reassuring victory for American agriculture and ecosystems—the sort of save that happens every day on American borders. Ample experience with the destructive power of invasive species, from the gypsy moth to the emerald ash border, has taught this country the importance of being alert to imported danger.

Other nations aren’t so careful, according to a new study in the journal Nature Communications, and that’s likely to become a major problem, especially for low-income countries, as global trade and travel continue to expand. Most such countries, the authors found, now focus their border screening efforts on five or fewer species they regard as potential threats. To put that in perspective, the United States alone now has 30,000 invasive alien species, and they do an estimated $148 billion worth of damage every year. Countries without proper screening have no idea just how big a risk they are taking.

The threat from invasive species in coming decades will “differ markedly from current threat levels,” the authors wrote, and will come down hardest on regions “where economies and food production systems are often fragile and human populations are particularly vulnerable to food shortages.” Wildlife and plant species will also suffer because many of those same countries are home to major biodiversity hot spots, particularly in Central America, Africa, central Asia, and Indochina.

The new study is worth thinking about because of a trend among certain ecologists to argue that the invasive species problem is exaggerated and that we should all just relax a little. A separate and unrelated trend treats concern about alien invasive species as some kind of nativist bigotry, “biological xenophobia,” like Donald Trump raving about Mexicans and Muslims. One animal rights activist has even likened these programs to Nazi genocide, writing, “The types of arguments made for biological purity of people are exactly the same as those made for purity among animals and plants.” But people facing the invasive species problem in the developing world would roll their eyes at such arrant nonsense.

“This is not about some campaign to maintain an artificial purity,” said Jeffrey S. Dukes, an ecologist at Purdue University and coauthor of the new study. “This is about doing our jobs as stewards of a sustainable planet.” Among the countries the study identified as unprepared to deal with the threat of invasive alien species, Dukes listed Peru, Papua New Guinea, Malaysia, and Thailand—all hot spots for species diversity. All are also highly vulnerable subsistence economies.

“In developing countries,” said Dukes, “people live much closer to the land, they are much more dependent on benefits from nature, and they are much less insulated from fluctuations in crop output or any kind of economic mishap. So you have a situation where there is very little protection against species coming in and causing problems and very little protection for people once those things arrive. Anything we can do to prevent people in the developing world from dealing with these long-term problems is going to prevent potentially catastrophic changes in their lives.”

One problem for custom agents in border countries is that invasive species can be difficult to identify or even to see. One of the pests found in the North Dakota incident, for instance, was a miniature fly. It looks trivial but can decimate fruit orchards. Another worrisome invader, Panama disease, is a soil fungus that targets banana plants. A poorly trained customs agent might not even know to look for it. But in the 1950s, a strain destroyed the world’s most popular banana variety, the Gros Michel, and wiped out farms across Central and South America. Now a new strain from Taiwan threatens the Cavendish banana, which replaced the Gros Michel.

Likewise, Tuta absoluta is a serious moth, with a tiny caterpillar that burrows into plant leaves, making it hard for an untrained custom agent to detect. It has thus hitchhiked around the world from its home turf in South America. In Nigeria, they call it “tomato Ebola,” and this year it destroyed 80 percent of the tomato crop, driving the price from $1.20 to $40 a basket over just three months.

The new study urges vulnerable countries to start the process of protecting themselves by making a proper inventory of invasive alien species that are already present. They need to begin having a conversation about finding cost-efficient strategies, said Dukes, for instance, by coordinating with neighboring countries and taking advantage of international programs. The lesson from encounters with Panama disease, Tuta absoluta, and other invasive pests is that it’s infinitely cheaper to prevent the problem from getting started than to fix it when it’s too late.

There’s one way ordinary travelers can help. The biggest threat in low-income countries comes not from trade, surprisingly, but from air-passenger traffic. That bit of fruit or meat people smuggle into the country with the idea that it’s harmless can easily conceal a catastrophe for people and ecosystems that can least afford it.