The Associated Press investigated the use of so-called “biological controls” across the country, and found troubling evidence that some imported insects brought in to fight invasive bugs are turning into pests that threaten native species.
Do you agree or disagree with the idea of using exotic species as a weapon against exotic species?
The argument in favor of these biological controls is that they can be less harmful than chemical pesticides.
But the Associated Press found that the federal government does little, if anything, to follow up on these introductions of biological control agents and find out if they are working as intended – or wreaking havoc on the ecosystem.
“A weevil released to attack a weed has veered off target and is gobbling up a native plant in Nebraska,” the AP reports. “A fly that was supposed to kill invasive moths is wiping out native moths in New England. And an insect introduced to combat a pesky weed led to a spike in the population of mice carrying a potentially deadly virus in Montana.”
“The U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) has approved hundreds of biocontrol agents since the early 1970s…..(But) the agency does not know what happened to most of the biocontrol agents it approved for use.”
The question of what to do about invasive species in the Chesapeake Bay is a thorny one. Maryland has been using biological controls to contain an invasive flowering plant from Eurasia called purple loosestrife. Scientists release tiny Eurasian beetles called Galerucella to devour the fast-growing plant. But state officials say the Galerucella eats only this one kind of exotic plant -- and so therefore poses no threat to other plants or insects. And there is no evidence that the introduction of this beetle has caused any harm.
Maryland wildlife biologists used poison to try to eliminate carnivorous Asian snakeheads when they were found in a Maryland pond a few years ago. But that failed to stop their escape into Potomac River tributaries, where they are now reproducing on their own.
An even more destructive invader, the European mute swan, has been gobbling up valuable underwater grasses in the Bay and driving away native birds. In response, Maryland has been conducting a campaign to spread oil on the eggs of the swans (smothering them) and take other lethal measures to control the population.
The U.S. Fish and Wildlife service also works with state biologists to trap and kill south-American rat-like creatures called nutria that devour the roots of important marsh grasses in the Blackwater National Wildlife Refuge on Maryland's Eastern Shore.
What measures do you think are appropriate to control invasive species? Introducing other exotic species? Poisons? Nothing? Perhaps the only answer is public education to prevent introductions in the first place?
(Photo by Richard Baumann)