A beetle larva is attached to an amphibian host. (credit: Gil Wizen/AFTAU )
We often think of amphibians such as toads hunting beetles for food, but there are exceptions to this when roles are reversed and the amphibians become the prey of beetles. Zoologists from Tel Aviv University have recently published a study on PLoS ONE about ground beetle larvae that does a dance to attract their prey.
Despite a major size advantage it appears that the larvae are very effective at attracting the amphibians and are fast enough to evade the tongue and then lunging at the toad and attaching itself to the toads body where it will spend the rest of it’s cycle attached to the mouth or throat area feeding on the fluids as a parasite.
Beetles life cycle closely intertwined with amphibians.
When the larvae needs to mature to the next stage the larvae will fall off the amphibians leaving a nasty scar. The next stage of the larvae is more damaging to the amphibian as the second and third stages of larvae will start to chew on and eat the amphibian itself.
Things don’t get much better for the amphibian when the beetle reaches adulthood. The adult beetle will ambush the amphibian and bite into it’s back making a small incision. This is thought to cut into the spinal cord or one of the muscles and prevent the amphibian from jumping away. The beetle then settles down to feast on it’s prey.
Attracting the amphibian with a dance.
The study by zoologist, Gil Wizen, wanted to look at more details about how the larvae attracted the amphibian. Amphibians hunt based on movement and wizen discovered that the larvae performed a sequence of movements that attracted the attention of the amphibian.
The movements included opening and closing it’s jaws and waving their antenna from side to side in some macabre death dance. As the amphibian shoots out it tongue to catch the larvae the beetle jumps out the way and attaches itself to the amphibian.
“It’s really a predator-prey role reversal — the insect actually draws in its potential predator instead of avoiding it,” says Wizen. “It’s quite a unique phenomenon.“
Getting a second chance at the amphibian.
The larvae does’t get the upper-hand every time though, on rare occasions the amphibian will capture and swallow the larvae. Success doesn’t last very long though and the amphibian will invariable regurgitate the larvae giving the beetle a second chance to attach itself to the amphibian.
Wizens work is to help understand the threats to the amphibians of the region. As a very dry environment many of the different amphibians in the region are threatened with extinction. When a species lives in such a harsh environment it is always close to the edge of survival and a greater understanding is needed of the amphibians habitats and natural threats in order to put together effective conservation strategies.
External sites:
Video of the larvae movements (asx file).
PLoS ONE: An Unprecedented Role Reversal: Ground Beetle Larvae (Coleoptera: Carabidae) Lure Amphibians and Prey upon Them.
