Athens, Ga. A University of Georgia researcher studying invasive ladybugs has developed new models that help explain how these insects have spread so quickly and their potential impacts on native species.
In recent years, some people have noticed swarms of ladybugs amassing in the fall, even infesting their homes. These are Asian lady beetles, insects native to eastern Asia, introduced to the U.S. as a biocontrol for aphids and have since spread throughout the country and into Canada. When he found the beetles in his own home, Assistant Research Scientist Richard Hall, of the UGA Odum School of Ecology, was motivated to learn more about them.
Hall knew that the Asian lady beetle had only recently, in 2004, arrived in his native England, and is already found all over the U.K. Data collected as part of a citizen science effort based at Cambridge University shows it to be one of the fastest documented invasions ever by an insect. He also knew that in the U.S., the Asian lady beetle has excluded many indigenous ladybugs from parts of their original range.
"I wanted to know how this insect could have invaded the U.K. so quickly," Hall said. "And I also wanted to know what the impacts on native species are likely to be." He has just published two new papers that explore these questions in the journals Biology Letters and Ecology.
"What makes this insect a good biocontrol also makes it a good invader," Hall said. "It has multiple generations per year, compared to just one for native British ladybugs. It tolerates a wide range of environmental conditions. And it has a generalist dietit likes aphids, but it will also eat other ladybugs. In other words, it eats its own competition."
Hall explained that when an invader expands into an open niche, with no native competitors present, invasion happens faster than if a competitor was already there; native competitors slow the rate of invasion. If an invader can e
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University of Georgia