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5 December 2013 11:26 am ,
Vol. 342 ,
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Mighty Mites Get Chomped
9 July 1999 6:00 pm
BOZEMAN, MONTANA--In an ironic twist, a mighty mite that scientists hoped would devour unwanted weeds has itself become dinner for another introduced insect. The finding, presented here this week at the 10th International Symposium on Biological Control of Weeds, highlights the complexities facing scientists involved in biological control, which aims to fight weeds and pests by unleashing their natural enemies.
In the late 1800's, a Scottish lord exported a European shrub called gorse to use as hedgerows on his Oregon landholdings. Since then, gorse has run wild throughout the Pacific Northwest and Hawaii, forming dense thickets that crowd out native vegetation and wildlife. In the 1980s, researchers in New Zealand--where gorse is also a problem--identified a pinhead-sized European spider mite that has a voracious appetite for the weed, and released it. U.S. researchers followed suit in 1994, letting swarms of the tiny insects loose at several Oregon gorse groves. At first the bugs defoliated large swathes of gorse, but their populations plummeted within a few years, leaving the weeds once again unchecked.
Entomologist Paul Pratt of Oregon State University in Corvallis and colleagues from the Oregon Department of Agriculture took a close look at three mite sites. Not surprisingly, they found that native predatory insects--including other mites--had learned to snack on the newcomers. But they soon suspected that a previously undetected insect, another mite introduced years earlier in the United States to hunt down crop pests, was doing much of the damage. Lab studies, including one in which the two mites were pitted against each other in 2.5-centimeter-wide "arenas," confirmed that the earlier import was chowing down on the gorse mites. Further proof should come this summer, when Pratt finishes field studies involving the use of chemicals to remove only the predatory mite from mite colonies, and seeing how the weed-eaters respond. If the predator-free colonies thrive, that suggests the predator mite is doing most of the damage, he says.
The study documents just one of the obstacles that biocontrol researchers face, says Bob Pemberton, a U.S. Department of Agriculture biocontrol expert in Fort Lauderdale, Florida. Indeed, other researchers presented statistics showing that scientists often introduce several unsuccessful biocontrol insects before picking a winner. But Pratt says his findings offer a hint at improving the odds of success: By surveying potential release sites for problematic predators, researchers may be able to better predict which weed munchers will thrive.