Category: ladybug

One way to successfully invade a habitat: eat the competition

One way to successfully invade a habitat: eat the competition

 

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Harmonia axyridis, adulte The Harlequin ladybug, Harmonia axyridis. Photo by Ombrosoparacloucycle.

ResearchBlogging.orgThe Asian Harlequin ladybug, Harmonia axyridis, eats aphids like they’re Popplers, and it’s been repeatedly introduced into the U.S. and Europe to do exactly that. But since it was first introduced, H. axyridis has spread of its own accord, and displaced native ladybugs. This isn’t just because the Harlequin ladybug eats more aphids, or breeds faster, than the locals; it looks like part of the Harlequin’s success is due to the fact that it eats its native competition.

Although they’re known for eating aphids, most ladybugs are perfectly willing to engage in intraguild predation—that is, to eat other insects that are themselves primarily predators. Including other ladybugs. So a team at Wageningen University in the Netherlands set out to see whether H. axyridis might engage in a different kind of intraguild predation than its native competitors—do the Harlequins preferentially attack ladybugs of different species, and, when they do, are they more likely to win?

The team tested this in what they call a “semi-field” experiment, by creating encounters between ladybug larvae on individual leaves of small potted lime trees. They chose two other ladybug species, Coccinella septempunctata and Adalia bipunctata, for comparison to, and competition with, H. axyridis. Then, on the leaves of small potted lime trees, the researchers set up larval ladybug death matches.

Death matches for science, mind you.

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Source: New feed