What do invasive plants and animals have to do with homeland security? The March 2005 issue of National Geographic reports that “terrorists could use invasives as weapons to ‘disrupt and demoralize the U.S. government and its citizens over time.'” This according to Parameters, the U.S. Army College quarterly.

Dubious about the connections between national security and some turtles and weeds? How about economic concerns? “Attack of the Alien Invaders” also reports that “invasives cost the U.S. alone more than 140 billion dollars yearly.” For example, the Caribbean tree frog, called a coqui, has “dampened [Hawaii’s] 80-million-dollar nursery export business.” Lost revenue aside, these little buggers can sound like “a thousand car alarms shrilling in your garden all night.” Bummer.

And then there are possible health implications, such as the 2003 case of monkey pox, which jumped from infected African rats to pet prairie dogs to more than 70 people in six states. Luckily, no one died, but this illustrates how alien species can introduce alien viruses and the need for someone to stay on top of this issue. [See Grist‘s article on conservation medicine in Main Dish.]

But the most obvious concern around invasive species is their impact on local ecosystems. Non-indigenous animals can eat and compete with natives species — sometimes wiping them out. Invasive plants can choke out natives, which can also impact the animals dependent on those plants as food sources. Check out the Global Invasive Species Database for “100 of the World’s Worst Invasive Alien Species,” which has been reproduced in the current issue of National Geographic.

Not a National Geographic subscriber? Check out the various Grist stories on the topic. And if you do get NG, browse our archives anyway! Where else are you going to learn that goats are the hip new thing in eco-friendly weed management?

Have your own invasive species horror story? Do tell.