Image of the Day: Beetle Fight
Image of the Day: Beetle Fight

Image of the Day: Beetle Fight

The exaggerated horns and elongated forelegs of male flower beetles, which use these appendages as weapons in combat for females, do not slow down the insects in a race.

Jef Akst
Jef Akst

Jef Akst is managing editor of The Scientist, where she started as an intern in 2009 after receiving a master’s degree from Indiana University in April 2009 studying the mating behavior of seahorses.

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Dec 3, 2018

ABOVE: A male flower beetle (top) guards the female beneath him as an intruding male comes near.

Sexually selected traits sometimes come with a cost. One risk is that oversized structures intended to attract the ladies may hinder mobility. But in male flower beetles (Dicronocephalus wallichii), the size of their sexually selected horns and forelegs appear to have no bearing on how fast they can scurry across bamboo branches propped at different angles in the lab.

“Our results suggested that no negative relationship exists between relative foreleg length or horn length and sprint speed,” the authors write in their paper, published this month (November 18) in Ethology. In fact, the researchers found that beetles with longer horns could actually run faster on horizontal branches. “Males with longer horns probably have more energy and/or invest more heavily in appendage musculature,” they speculate. “As is known...

W. Kojima, C.-P. Lin, “Sprint speed is not reduced by exaggerated male weapons in a flower beetle Dicronocephalus wallichii,” Ethology, doi:10.1111/eth.12824, 2018.

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