新托福阅读材料：8WildWaystoCombatInvasiveSpecies（5）

外来入侵物种对本地区的生态系统会造成许多不良影响，科学家们用自己的聪明才智研究出了许多对抗这些“外来侵略者”的有趣方法。接下来我们就一起来看看吧!

 

　　Lamprey Love Potion

 

　　Sea lampreys earned the alias "vampire fish": After all, they suck blood. These long, parasites are similar to eels and use their suckerlike mouths to latch on to the bodies of other fish. Then they rasp a hole in the fish's skin with their tough tongues. In the Atlantic Ocean, the lamprey's home, this isn't such a problem: The fish are big, and they can spare some blood. But in the Great Lakes, where lampreys arrived a century ago, the fish are smaller, and a lamprey bite can be deadly. "Many fish that get attacked by the sea lamprey eventually die," says Weiming Li, a fisheries professor of at Michigan State University. In fact, these slimy suckers were at least partly to blame for the collapse of lake trout, whitefish and chub populations in 1940s and 1950s.

 

　　Lampreys, which breed in freshwater streams and tributaries, find their mates by scent. In 2002 Li and his colleagues identified a pheromone that male lampreys use to attract their mates. Perhaps, they thought, we can use the chemical to lure lampreys into particular streams to make trapping easier. So the researchers created a synthetic lamprey love potion.

 

　　Over the past few years, they tested it out in a few "pristine" streams, places where lampreys don't already breed. Li and his colleagues found that just a small amount is enough to lure females into these waterways. This year they started testing the compound in streams where lampreys already breed. So far, the results look promising, Li says.

 

　　Using pheromones to lure females into areas where they can be easily trapped is the most straightforward application, Li says, but the synthetic chemical could be used in other ways, too. He envisions employing it to coax female lampreys into areas where their larvae are less likely to survive.