Are toad tadpoles unpalatable: evidence from the behaviour of a predatory dragonfly in South China

Predators are important determinants of amphibian community structure in aquatic habitats, and larval odonates can be significant predators of amphibian larvae. Despite their toxicity as adults, the palatability of bufonid eggs and tadpoles to vertebrate and invertebrate predators remains widely debated. I tested the palatability of hatchling tadpoles of the Asian common toad (Bufo melanosticus) and four other amphibians in Hong Kong to larvae of the dragonfly Pantala flavescens. Attempted predation of Bufo melanostictus hatchling tadpoles by P. flavescens resulted in 100% mortality of hatchlings, but none were consumed. All other amphibians were palatable to P. flavescens. Development of toxins may not protect early-stage bufonids from invertebrate predators that detect prey by visual cues and then make a debilitating strike. These findings present the first report of unpalatability of bufonid tadpoles to an invertebrate predator and provide evidence that unpalatability of early stage bufonids to odonates may decrease through ontogeny.