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April 18, 2007

Peak Pest Period: Invasives & Summer Travel

We touched down in Nairobi, Kenya, in the early morning as the day was just beginning and the temperature was still mild. It was our second international stop on our trip around the world, and we were tired but excited.

As we taxied to a stop, flight attendants walked swiftly up and down the cabin, spraying a white fog of undefined purpose. We all covered our faces, coughing. Not the most pleasant experience, but at least on our flight out when they did it again, they explained that it was a pesticide and we could cover our faces if we wanted, but it had "no harmful effects" for humans.

I give them an A for effort and a D for execution, since no one, not even the flight attendants, could explain what or why, just that they had to do it as a policy. Invasives sneak into your luggage, and travel along with you, just like the flu virus travels the world, and all have found airplanes to be the best mode of travel.

Think about it: a hitchhiking insect or plant is more likely to make it to the new environment if it gets there quickly. Slow trains and ships often subject goods (and people) to drastically different conditions such as extreme heat and cold, on the way to the destination, whereas the regulated cabin of an airliner is designed as an enclosed pocket of steady climate for you reach your destination comfortably and quickly. Even if the invasive arrives in bad shape, if the destination provides a welcoming habitat, then the invasive can recover - often with disastrous results.

This new research may help explain why:

...research reveals that—as for people in many countries—June, July, and August are the peak months for long-distance travel.

Previous studies have shown that international flights are a significant factor in unwelcome insect invasion. Some 73 percent of recorded pest interceptions in the U.S., in fact, occur at airports.

...

Pest transfer between far-flung locations is more likely when the weather is similar in both regions, making it easy for the pests to settle into their new home.

...

"Hawaii, with its moderate year-round climate, is a hot spot for pest invasions," Tatem said. "It is linked to a similar climate in Central America in April, Asia in July, and the Caribbean in October."

In general, though, June, July, and August are the peak months for insect travel.

More At: National Geographic: Invasive Bugs, Plants Prefer Summer Plane Flights

California has agricultural screening facilities on every major highway in and out of the state, but anyone who goes to Tahoe with any regularity knows that they are not always open. When I drove here from Vermont one summer, we camped along the way. At the California border, we had to fork over our head of lettuce. It was the end of summer then, though, whereas the Tahoe Truckee ag station is only a handful of miles from where the Donner Party camped - not much can live at that altitude without a Safeway and PG&E. Still, many coastal areas have very small fluctuation in temperature and rarely get a frost. These areas are more likely to host invasives.

Ironically, one of the invasive plants most complained about in Santa Cruz is the Ice Plant, which grows along highways and seacliffs, choking out natives. Where ice plant grows, little else does. According to Wikipedia, it was Caltrans that first started using ice plant along railways and roadsides, because it grew easily all year round, with low maintenance and pretty flowers, and more importantly, it provided a fire barrier. It also only grows a few inches high, so trimming it would not be an issue. Several killing frosts over the past few decades have decimated swaths of ice plant in Santa Cruz county, leaving it patchy at best.

Perhaps you've had your shoes treated after a trip from Europe, or had your bags Ag-screened after a trip to Hawaii, and you probably thought it was an annoyance. This summer, when you make your travel plans, give a little thought to what you're tracking and where it may be going.

Posted by sorsha at April 18, 2007 11:22 AM