Invasive ladybugs eat their native competition, but a shared enemy determines who survives

Beth Gavrilles in the UGA News: 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.

… 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. …“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 diet—it likes aphids, but it will also eat other ladybugs. In other words, it eats its own competition.”

…Hall developed a model, published in the current issue of Biology Letters, that explains his findings and predicts that invasive species that feed on both lower-level food sources and species that compete for these same food sources will be more successful, and spread faster, than those that only feed on lower-level sources.

…Hall said that [his] models could be applied to other species where the invader preys on, as well as competes with, a native species. “It is important to take into account the effects of a natural enemy on that interaction in order to avoid incorrect predictions about which species will persist,” he said. “And accurate predictions are crucial for developing successful management strategies.”

A ladybug shot by Pudding4brains