Northern Research Station News Releases

Media Contact

Invasive Insects Keep On Invading

Study reveals that secondary introductions act as a critical driver of increasing global rates of insect invasions

Nearly a century of data on ant interceptions at air and maritime ports in the United States and New Zealand was used in an analysis of global invasive species introduction, spread and subsequent invasion. Photo shows an Argentine ant, photo credit: www.AntWeb.org Newtown Square, PA, May 10, 2018 - In the most comprehensive global assessment of secondary insect introductions, a team of scientists from the USDA Forest Service, the University of Lausanne, University of Paris-Sud, the New Zealand Forest Research Institute and Landcare Research found that a surprisingly large number of invasive ant species intercepted at borders in the U.S. and New Zealand came not from their native range, but from other invaded regions.

The study, “Recurrent bridgehead effects accelerate global alien ant spread,” was led by Cleo Bertelsmeier of the University of Lausanne and published in the journal Proceedings of the National Academy of Sciences. It is available through the USDA Forest Service’s Northern Research Station at: https://www.nrs.fs.fed.us/pubs/56128

Co-author Andrew Liebhold, a research entomologist with the Northern Research Station in Morgantown, West Virginia, and his colleagues used more than 70 years of data on ant interceptions at air and maritime ports in the United States and New Zealand in the analysis of global introduction, spread and subsequent invasion. Researchers found that between 1914 and 1984, 51 alien ant species were identified in 1,428 interceptions made by USDA inspectors at ports of entry in the United States. In New Zealand, a total of 45 alien ant species were identified in 3,105 interceptions between 1955 and 2013. In the U.S., more than three-quarters of the intercepted ants came from outside of their native range; in New Zealand, 87 percent of the ants intercepted came from outside of the native range. 

“Biological invasions represent serious threats to forest health,” said Liebhold. “More than 400 insects have invaded the United States over the past 200 years, and several have significantly changed the nation’s forest landscape. These results reveal that secondary introductions act as a critical driver of increasing global rates of insect invasions.”

The research team suggested that one reason insects may become repeat invaders is that they become more abundant when they arrive in a new territory, where they lack natural predators and competition. Researchers also suggested that there could be a “small world” component of insect invasion in that transportation hubs provide multiple ways for insects to arrive and then disperse through a region.

In addition to Bertelsmeier and Liebhold, the paper’s authors included Sébastien Ollier of University Paris-Sud, Eckehard Brockerhoff of the New Zealand Forest Research Institute, Darren Ward of Landcare Research and Laurent Keller of the University of Lausanne.

###

The mission of the Northern Research Station is to improve people's lives and help sustain the natural resources in the Northeast and Midwest through leading-edge science and effective information delivery.

###

The mission of the U.S. Forest Service, an agency of the U.S. Department of Agriculture, is to sustain the health, diversity and productivity of the nation's forests and grasslands to meet the needs of present and future generations. The agency manages 193 million acres of public land, provides assistance to state and private landowners, and maintains world-renowned forestry research and wildland fire management organizations. National forests and grasslands contribute more than $30 billion to the American economy annually and support nearly 360,000 jobs. These lands also provide 30 percent of the nation's surface drinking water to cities and rural communities; approximately 60 million Americans rely on drinking water that originated from the National Forest System.

###

USDA is an equal opportunity provider and employer. To file a complaint of discrimination, write to USDA, Assistant Secretary for Civil Rights, Office of the Assistant Secretary for Civil Rights, 1400 Independence Avenue, S.W., Stop 9410, Washington, DC 20250-9410, or call toll-free at (866) 632-9992 (English) or (800) 877-8339 (TDD) or (866) 377-8642 (English Federal-relay) or (800) 845-6136 (Spanish Federal-relay).


Last modified: May 10, 2018