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Globally, the presence of non-native species results in a loss of $423 billion each year, with a large amount occurring in the United States. It is believed that they cause about $120 billion in damage every year, although this estimate is outdated as it is from 2005.

Human actions have led to the introduction of more than 37,000 species to new environments, whether through travel or the movement of goods. These species, including animals, plants, algae, and disease-causing insects, are brought to new locations intentionally or accidentally via land or water. Once they become established, they can out-compete native species, harm existing ecosystems, and spread diseases.

David Wilcove, a professor of conservation biology at Princeton University, stated that Hawaii has the highest rate of species extinction globally. In a recent event, eight bird species native to Hawaii were declared extinct, largely because of illnesses transmitted by non-native mosquitoes. These mosquitoes are carriers of avian malaria and avian pox, which have greatly impacted the Hawaiian birds due to their vulnerability to these diseases.

Some invasive species are not damaging, and many non-indigenous species, such as cattle, wheat, and honey bees, hold significance in the United States.

There are five species that are not native to the US and are causing concern among many people.

Zebra mussels

Zebra mussels were first detected in the US in the 1980s. Native to Eurasian waters of Caspian and Black Seas, this freshwater mussel has since spread to the Mississippi River, Great Lakes, Hudson River, Lake Travis and other bodies of water. Growing into large clusters, these mussels not only disrupt ecosystems by attaching to shellfish and filtering out the algae they consume, but also clog water treatment plants, costing US over $1bn in damages a year.

Welcome stated that no one had planned on bringing them to this location. It is probable that they were unintentionally transported in the ballast water of a ship, which is used to maintain the ship’s stability. Wilcove mentioned that they were released into the Great Lakes and had a remarkably high level of success.

Spotted lanternflies

In 2014, this harmful bug was initially observed in the United States and has since expanded its presence to states such as New Jersey, Connecticut, Maryland, Virginia, Indiana, and Ohio.

The lanternfly most likely arrived in the US through a trade shipment and then traveled through different states by hitchhiking on various modes of transportation such as trains, cars, trucks, and planes. Despite its name, the lanternfly is not skilled at flying. A recent economic report from Pennsylvania, where the insect was first introduced to the US, predicts that it could cause an annual loss of $324 million, primarily affecting the wine industry. The spotted lanternflies feed on grapevines and can harm trees and crops, leading some states to use insecticides in an attempt to manage the population.

Ornamental plants

Ornamental invasives, such as Japanese barberry, baby’s breath, and blue lyme grass, are plants that are sold in nurseries and plant shops. Although they may not be as damaging as other invasives, some of these plants were initially introduced to gardens for their unique qualities. However, they have adapted to their new environment and have the ability to spread beyond the gardens, outcompeting native plants.

Wilcove stated the need for efficient identification of potentially troublesome species. The US policy allows the importation of any species not on the prohibited list, also known as the blacklist. This creates a presumption of innocence until a species is proven harmful. However, the uncertainty surrounding which species will cause problems poses a challenge.

European starling

In 1890, a group of bird enthusiasts introduced this particular bird to New York’s Central Park. Their goal was to bring every bird species mentioned in Shakespeare’s works to the United States. However, this bird ended up posing a threat to the eastern bluebird, which is the state bird of New York, as they competed for nesting sites and almost drove the bluebird to extinction.

Starlings are considered a nuisance in farming as they consume food intended for livestock and can harm fruit and grain crops. In 2000, research estimated that starlings caused $800 million in damages, but this number is likely to have increased since then. The wildlife service has taken measures to manage the bird population, resulting in over one million starlings being killed in 2021.

Feral pigs

Feral pigs are a highly damaging invasive species on a global scale. They can be found in at least 35 states and consume vegetation, causing destruction to plants and their roots. This not only affects the soil but also endangers the survival of rare plants. Additionally, feral swine carry numerous viral and bacterial diseases, as well as parasites that can be transmitted to humans and other animals. The issue is particularly concerning in the southern regions of the United States, with Texas being significantly affected as these animals can be found in every county and hunting them is permitted. According to the US Department of Agriculture, the annual cost of damages caused by feral pigs is estimated to be around $2.5 billion.

Similar to the species that pose risks in the US, numerous native US species create significant issues in other regions of the globe.

The grey squirrel from North America is classified as an invasive species in the United Kingdom. They carry a lethal virus called squirrel pox and outcompete the native red squirrels for food by consuming seven times their own body weight.

“It’s a problem that affects the entire world,” Wilcove stated. “Blaming a specific region for the introduction of its species is unreasonable.”

Source: theguardian.com