Small, Sometimes Invisible Invaders Draw Increasing Attention

December 22, 2010

Hundreds of species of tiny, sometimes invisible insect and microbial predators are among the hordes of invasive species that cost billions of dollars to fight each year, and that continue to cause major environmental disruption despite such efforts.

The nemeses often come into the country while hitchhiking on some of the billions of pieces of goods imported each year, such as shipping containers, plant material, and wooden handicrafts, or through processes such as ballast water discharges. They spread by flying, floating in the wind, attached to products such as ships, nursery plants, or wood products, and in other ways.

Some of the latest knowledge about these invaders has been unveiled in two recent studies. One looked at problems in urban and natural forests, and the other focused on microbial pests in various settings.

  • "Historical Accumulation of Nonindigenous Forest Pests in the Continental United States," BioScience, December 2010, Juliann E. Aukema, et al.; Dec. 6, 2010, American Institute of Biological Sciences press release, "Forest Pests Accumulating Despite Regulations" (through early January 2011, contains link to full study).
  • "Invisible Invaders: Non-Pathogenic Invasive Microbes in Aquatic and Terrestrial Ecosystems," Ecology Letters, December 2010, by Elena Litchman; Dec. 7, 2010, Michigan State University press release, "Invisible Invasive Species Altering Ecosystems" (includes link to full study).

In natural and urban forests all over the country, there have been at least 470 invading insect and pathogen species over the past century and a half, and major new nemeses continue to turn up at the rate of one every two years or so. Recent examples include emerald ash borer, Asian gypsy moth, Asian longhorned beetle, laurel wilt disease, and sudden oak death. The authors say that, until this study, no one had comprehensively investigated the temporal patterns for invading forest pests. The authors found numerous distinct patterns that may provide insights for efforts to mitigate and prevent problems.

Current procedures and regulations used by the Dept. of Homeland Security and US Dept. of Agriculture have failed to stop the problems, the authors say. One primary recommendation of the study is to improve prevention efforts at points of importation (including shippers and travelers), since eradication of problems seems to be nearly impossible once the invaders gain a toehold.

The study was funded by the National Center for Ecological Analysis and Synthesis (which is supported in part by the National Science Foundation) and The Nature Conservancy. The researchers are from the US Forest Service, Univ. of California, Santa Barbara, Michigan State Univ., and Univ. of Central Florida.

For two examples of media coverage, see:

In her review of even less-visible invaders, Michigan State Univ. associate professor Elena Litchman (269-671-2338) focused on culprits such as viruses, bacteria, fungi, and genetically modified microbes, including recent problematic examples such as blue-green algae, diatoms, and destructive soil microorganisms.

She says that very little is known about the problems that these pests can cause, though numerous hints of their destructive power exist. She speculates that problems could become even worse with climate change and accompanying extreme weather events, since those can provide additional avenues for invasion. Her review of this issue provides numerous hooks for delving into specific problems and general angles.

Your coverage of the invasives issue can focus on the locations at which invaders arrive; agencies tasked with preventing or coping with problems; locations where each individual invader is having an impact; organizations, companies, and individuals trying to cope with the impacts; researchers investigating the culprits, their impacts, mitigation techniques, or prevention; economic impacts that could occur as a consequence of preventive actions; and national security impacts of preventive actions (such as diluting anti-terrorism efforts if money and staffing at airports, ports, and borders aren't increased to enhance screening efforts for invasives).