Lucky for the beetles, loosestrife grows in North America like, well, a weed. When the tall, hardy plants with bright purple, conelike flowers first arrived from Europe in the 19th century, they found no enemies, just fertile soil. In marshes, especially, loosestrife took over like kudzu. Now, a century later, this unchecked growth threatens local wildlife, which depends on other plants for nesting materials and food. In another time, hard-pressed naturalists might have reached for pesticides or poisons, but today those are environmentally incorrect - and often plain dangerous. Instead, scientists looked for a ““biological control’’ for the loosestrife problem. In other words, they sought to turn Mother Nature against one of her own.
Biocontrol is not an overnight solution. Blossey, a Cornell ecologist, spent much of the last 10 years looking for natural enemies of loosestrife. In Europe, he found two beetle and two weevil species that ate only loosestrife. Then, having conquered the world of bugs, he had to take on the U.S. bureaucracy. Before he could bring his critters into the country and release them, he had to clear both federal and state review boards. The regulators are there to prevent the biodisasters so far seen only in sci-fi thrillers: a beetle that loves loosestrife but also has a taste for unhusked corn or human eyeballs. Blossey’s research put such fears to rest. But biocontrol is a technique subject to the laws of unintended consequences.
Take the rabbits in Australia (and the locals wish you would). Twelve rabbits were introduced to the bunnyless island in 1859, and within 100 years, hundreds of millions of rabbits were scampering across the plains, destroying farmland and driving local animals from their native habitat. What to do? About a decade ago, an Australian ecologist came upon a virus that seemed to attack only rabbits. In 1995, he won permission to start studying the virus on an uninhabited island off the coast of South Australia. But the virus wasn’t contained; a simple housefly may have carried it to the mainland where it spread like loosestrife in a marsh. During the past year, millions of rabbits have died, victims of the virus.
Many Australians are thrilled; some scientists are wary. While there has yet to be any conclusive evidence that the virus can jump species, Alvin Smith of Oregon State University insists there’s no reason to think it couldn’t infect humans: ““If you were a betting man, that would be your bet.’’ The government organization in charge of testing the virus inoculated 40 other animal species, and none got sick. No human handlers of the virus did, either. Nonetheless, says a government researcher, ““You can’t make guarantees on any virus.''
Just last week, New Zealand authorities decided to delay the release of the virus, choosing to watch how it plays out in Australia. New Zealand has had bad experiences with biological controls; the stoats, ferrets and weasels introduced to cull the rabbits now threaten native animals.
The problem with the ferrets, and the worry about the virus, is lack of specificity. Ferrets eat everything. What makes Blossey’s beetles so successful is that they would rather starve to death than eat something that isn’t loosestrife. Some biocontrol agents aren’t so exacting, but that’s not necessarily a problem, as long as all the targeted species are pests. Metarhizium anisopliae, a fungus that kills insects by growing through their exoskeletons, is approved by the EPA for use against termites. It also attacks cockroaches and houseflies, but honeybees and ladybugs aren’t affected. Biocontrol, then, is a wonderful tool, as long as the cure doesn’t turn out to be worse than the disease.
