ABOVE: Diving beetle eggs (circled in red) laid on frog spawn hatch within hours of the emergence of the tadpoles the beetle larvae feed on.


The paper

J. Gould et al., “Diving beetle offspring oviposited in amphibian spawn prey on the tadpoles upon hatching,” Entomol Sci, 22:393–97, 2019.

While studying the conservation of endangered amphibians during his PhD at the University of Newcastle in Australia, Jose Valdez spent a lot of time peering into ponds looking for tadpoles. One night a few years ago, he noticed a group of predaceous diving beetles (family: Dytiscidae) ripping into a tadpole. Both larval and adult diving beetles are known predators of tadpoles, but witnessing the act himself, Valdez began to wonder about the influence of these invertebrates on amphibian survival. “These predators perhaps are overlooked,” he says.  

When Valdez surveyed ponds in a...

“The fact that they were hatching right at the right time to prey upon the tadpoles was pretty cool,” says Corinne Richards-Zawacki, an ecologist at the University of Pittsburgh who wasn’t involved in the work. “It begs more experiments to see whether or not this is something they do as an adaptation.” Either way, notes Valdez, the findings suggest that invertebrates such as diving beetles may be more important predators of amphibians than previously thought. 

The study is a prime example of “good natural history,” Richards-Zawacki adds. “Kudos for paying attention and taking the time to tease apart what was going on.”

Catherine Offord is an associate editor at The Scientist. Email her at cofford@the-scientist.com.

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