A Tale of Unintended Consequences

In a small niche of the forests of China, Korea and Japan, the Asian longhorned beetle evolved unnoticed. A hardwood tree pest with a black and white specked abdomen and long antennae, it survived in a pocket of hardwood trees amidst a largely evergreen Asian forest. Because the longhorned beetle feeds on the heartwood of hardwood trees only, the beetles’ populations remained low.

However, that changed in the 1960s and ‘70s, when the Chinese government planted large windbreaks of aspen trees to slow erosion and repopulate forests with hardwoods. Once the aspen forests matured in the 1980s, the beetle population exploded. Chinese foresters felled tens of thousands of acres of aspen and other hardwood trees to slow the beetle’s movement.

The deforestation succeeded in lowering beetle populations in China. However, the Chinese used downed trees to make crates and pallets. The larvae-infested crates filled with diapers, televisions, umbrellas and other goods traveled aboard ships to ports around the world. In New York in 1996, a Brooklyn resident reported the first finding of the Asian longhorned beetle in the United States.

This story, as told by author Peter Alsop in the November issue of Smithsonian magazine, weaves a tale of unfortunate consequences by unintentional human actions. If only the Chinese government had not planted trees atypical of the Asian landscape. If only foresters had destroyed the infested wood rather than reusing it for trade. If only…. Now the Asian longhorned beetle threatens hardwood forests in New York state, northern New Jersey, Chicago, Toronto and most recently, Worcester, Massachusetts, a town on the edge of the great Northern hardwood forest.

Like the longhorned beetle, most exotic insect and disease pests cross the border uninvited. Hemlock woolly adelgid, a tiny insect that is killing hemlocks along the east coast, accompanied an exotic hemlock that a Virginia plant collector planted in her Japanese garden. Asian soybean rust blew in to the U.S. with Hurricane Ivan. The emerald ash borer entered the U.S. in shipping containers and has been spread across state lines through infested tree stock and movement of firewood.

Most exotic invasives are established in an area long before they are considered a problem. The Asian longhorned beetle had been in Worcester for ten years before it was reported. The hemlock woolly adelgid, discovered in Virginia in 1951, was not considered a threat to hemlocks until the late 1980s, when entomologists discovered the pest in a natural stand of hemlocks along the York River.

Once established in the U.S., invasive species spread from state to state by weather, wildlife migration or human involvement. Alsop uses the example of a major ice storm in Worcester that closes roads and fells trees. Emergency crews from both within and out of the state respond to remove felled trees and limbs from roadways and haul them out of the city. In another state, another decade, another homeowner will call the U.S. Department of Agriculture and report a strange beetle on the trees. The cycle begins again.

The good news is that scientists and federal agencies are more vigilant and proactive about fighting invasive species. The bad news is that many times the fight takes years before it is successful. During those years, often intense losses can occur, such as the loss of the American chestnut to the chestnut blight.

However, modern advances in pest management have been able to begin restoring ecosystems. A national online warning and communication system called the ipmPIPE alerts growers to outbreaks of Asian soybean rust, soybean aphid, and other insects and diseases. The American Chestnut Foundation has successfully bred new American chestnut trees that are more resistant to the blight. That stock is now being reintroduced to the landscape.

Some pest management experts predict that the Asian longhorned beetle, emerald ash borer, hemlock woolly adelgid and other invasive insect species may eventually alter the American landscape by decimating forests. Other experts are resolved to prevent that alteration from happening. Until researchers find effective ways to manage these pests, communication and conservation will be key to saving America’s forests.

2 Responses

  1. […] A Tale of Unintended Consequences – this is a great story about Longhorned beetles […]

  2. […] A Tale of Unintended Consequences – this is a great story about Longhorned beetles […]

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