Research examines biological invasion

PULLMAN -As the citizens of Beijing prepare to welcome an invasion by athletes and spectators coming to this summer’s Olympic Games, a quieter and much less welcome invasion is already under way.
According to a new study co-authored by WSU ecologist Richard Mack, China’s explosive economic growth and ambitious public-works projects have allowed non-native species of plants, insects, and other organisms to spread throughout the country.
These have inflicted more than $14 billion of damage on the nation’s economy—and the Olympic Games, could provide a new entry opportunity for even more biological invaders.
Mack collaborated with four Chinese scientists on the report, which appears in the April issue of the journal BioScience.
The paper is titled, “China’s Booming Economy is Sparking and Accelerating Biological Invasions,” and can be found in BioScience vol. 58, pages 317-324.
The authors combed through trade and economic data to discover that China’s economic boom has been paralleled by a boom in biological invasions.
In the past 30 years, for example, the number of international ports of entry in China has doubled and the total length of express highways has expanded by 40-fold; and the number of invasive species in the country has more than tripled.
“They’re compressing the whole Industrial Revolution into about 40 years—and on a bigger scale,” Mack said.
The movement of introduced species across the nation has occurred at breathtaking speed—and enormous cost. For example, the American vegetable leaf miner, Lyriomyza sativae, was first detected in Hainan Province in December of 1993.
By early 1995 it had spread to 20 other provinces, and now it occurs throughout the whole country and causes at least $80 million of damages to vegetable crops every year.
China’s waterways have also become distribution systems for biological invaders. The Three Gorges Dam and a major canal project diverting water from the damp south to the drought-prone north could provide easy migration routes for aquatic invaders such as water hyacinth and alligator weed.
Both plants periodically block waterways in southern China, and have the potential to clog power turbines and water-intake pipes.
Mack said the unique ecosystems in remote areas of China and its neighbors are especially vulnerable to biological invaders.
Since they are not accustomed to dealing with new competitors, parasites, and predators, such regions could be quickly overwhelmed by aggressive newcomers.
Tibet, for example, has so far been relatively unaffected by the problems of invasive species. That could soon change due to the influx of new species carried in on new highways and the rail line that now runs from Beijing to Lhasa, Mack said.
The Olympics present another challenge: the entry of untold numbers of non-native seeds, spores and insect eggs that hitch a ride with the thousands of visitors and cargo containers that will converge on Beijing this summer.
Mack said the Chinese government recognizes the potential of the Games to lead to further problems with invasive species and is working on ways to detect and eliminate them before they gain a foothold.
However,the researchers also found that between 2002 and 2004, the Chinese government imported more than 31 million woody seedlings and 130,000 pounds of seeds to be planted in and around Beijing to ‘beautify’ the city in advance of the Games.
Some of those plants may themselves become invasive; and even well-behaved imported plants may carry invasive insects or parasites.
According to Mack, the most critical phase of the effort to deter Olympic invaders will come after the human visitors have moved on.
“The most likely way that any of these organisms are going to come in is in a resting stage—eggs, seeds, spores,”  Mack said. “That means they’re not going to be prominent at all when they first come in. So the Chinese will need to be alert with follow-up inspections.”
By that, he means inspecting the Olympics grounds during and especially after the Games. Programs to detect newcomers should continue for more than a year after the Games end, he said—the longer the better, because spores and seeds may not start growing right away.
Mack told Chinese scientists about one of the first such follow-up efforts, which occurred in Philadelphia following the city’s big Centennial Exposition in 1876.
“The city assembled a group of local botanists to walk the grounds of the exhibition halls for four years after it was over, looking for new species that would have come in,” he said. “I consider that incredibly insightful.”

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