Bufadienolide and alkaloid-based chemical defences in two different species of neotropical anurans are equally effective against the same arthropod predators

Abstract

Abstract:Defensive chemicals in anuran skin secretions function in protection against potential predators. Although studies have demonstrated that particular chemicals are effective against certain predators, very little is known about how different chemicals from different species function against the same predators. Understanding how different chemicals function as a defence against similar predators is fundamental to the ecology and evolution of chemical defences in frogs. In the present study, the defensive function of bufadienolide-based defences in adultRhaebo haematiticus(Bufonidae) were compared with alkaloid-based defences in adult and juvenileDendrobates auratus(Dendrobatidae) against the same predators. Most bufonids contain synthesized bufadienolides, whereas dendrobatids contain dietary-derived alkaloids. Predation trials were performed with two potential invertebrate predators,Paraponera clavata(bullet ant) andCupiennius coccineus(ctenid spider), to determine how these predators respond to two different types of frog chemical defence. The non-chemically defended frogCraugastor fitzingeriserved as a control in all predation trials. Our results suggest that bufadienolide defences ofR. haematiticusand alkaloid defences ofD. auratusare equally effective towards bullet ant and ctenid spider predators. The similar avoidance and cleaning behaviours exhibited by these ants and spiders after contact with bufadienolides and alkaloids suggest that both types of defence are unpalatable to these arthropod predators.