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The Continuing Saga of Invasive Species

The Ames, Iowa-based Council for Agricultural Science and Technology recently issued a report on the dangers posed by invasive pests to agriculture, public health, and natural ecosystems. A six-member task force co-chaired by Don Huber of Purdue University in West Lafayette, Ind., and Martin Hugh-Jones of Louisiana State University in Baton Rouge, documented research on the problem and recommended how to alleviate it. "If a pest can enter the United States, over time, it will find a way here, s

By | April 15, 2002

The Ames, Iowa-based Council for Agricultural Science and Technology recently issued a report on the dangers posed by invasive pests to agriculture, public health, and natural ecosystems. A six-member task force co-chaired by Don Huber of Purdue University in West Lafayette, Ind., and Martin Hugh-Jones of Louisiana State University in Baton Rouge, documented research on the problem and recommended how to alleviate it.

"If a pest can enter the United States, over time, it will find a way here, so a means must be found to develop appropriate, feasible, economic, and cost-effective quarantine and control procedures," says Huber. The report insists that a 'stew' of invasive pests and crops have breached "the once formidable geographic barriers posed by the Atlantic and Pacific Oceans through travel, trade, and transportation. The ecology of the western hemisphere has been changed by agricultural, social, and industrial activities."

The stew includes every class of organism, from viruses to fungi to plants to large animals. West Nile virus, chestnut blight, pigs, gypsy moths, pigeons, zebra mussels, purple loosestrife and bark beetles join about 50,000 other species on the US catalog of nonindigenous residents. Some arrive accidentally, as hitchhikers in ship ballast or in imported fruits, logs, and potting soil. Hundreds land each year. Others are introduced intentionally—a New York fan of the literature classics imported starlings in 1890 because Shakespeare mentioned them.

"Most introduced organisms fail to become established because they do not fit into the new ecological environment required for survival, reproduction and spread," notes the task force. They can't compete with species already here. The world also relies on many non-native species for food. Wheat, soybeans, cattle, and other staples account for 98% of the US supply at a value of about $800 billion (US) annually.

On the other hand, many invaders do overcome ecological and agricultural barriers and escape, wreaking widespread damage as a result. A study by David Pimentel and coworkers cited in the task force report estimated that U.S. losses from invasive species amount to approximately $137 billion annually. Pests put almost half of the nearly 1000 listed organisms on the threatened or endangered species roster. Invaders are the second leading cause of extinction, behind habitat loss as they clog waterways and pipes, crowd or root out native plants, kill wildlife and transmit disease to domestic animals and humans.

The CAST report blames the global pestilence on several factors, including "failure to train taxonomists and other diagnostic and control personnel." It also makes nine recommendations to help alleviate the situation:

  • Inform the public; emphasize control of global pest movement
  • Protect plant, animal and environmental resources
  • Prioritize highest-risk pests
  • Encourage and fund research into pest biology, impact, and control
  • Emphasize voluntary compliance rather than enforcement in controlling pest movement via travel, postal systems, etc.
  • Encourage private efforts; educate and train specialists
  • Establish science-based risk assessment and standards
  • Maintain vigorous response mechanisms that can react to threats quickly and effectively.
  • Periodically evaluate risks and regulations based on new knowledge>

    The lack of essential knowledge and resources is telling. According to the report, "the fact that different species can interact in many ways to exacerbate one another's effects and that they can move rapidly from one location to another means that limited databases will be unable to identify many potential problems, or possible means of dealing with them in a timely manner." Admits task force co-chair Hugh-Jones, "The total resources currently available are woefully inadequate for intervention, quarantine, removal, and enforcement. A coordinated network of professional societies, and state and national governmental entities is urgently needed along with an Internet-based data network with basic information on introduced species."

    Barry A. Palevitz (palevitz@dogwood.botany.uga.edu) is a contributing editor.


    For More Information:
    The task force report is available on the Internet at www.cast-science.org/castpubs.htm#ip20.


    See also:
    J. McCann et al., "Battling the bioinvaders," The Scientist, 15[18]:1, Sept. 17, 2001, and A.J.S. Rayl, "Bioinvaders proliferate in US waterways," The Scientist, 13[16]:6, Aug. 16, 1999.

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