A composição do veneno do sapo-cururuzinho muda de acordo com sua dieta?

Abstract

Most amphibians use chemical compounds against predators and pathogens. In some species, these compounds are synthesized in specialized glands, however, some anurans are known to sequester defensive compounds from their preys. There are several evidences of sequestering by Dendrobatidae frogs; however, studies with Bufonidae are scarce. Rhinella ornata (Bufonidae) is a common toad in Southeastern Brazil, which is threatened by forest fragmentation. According to previous results, this species feeds exclusively on the stinging ant Pachycondyla striata (Ponerinae). The objective of this study was to evaluate the relationship between the composition of the venom of R. ornata and the diet under laboratory conditions. Frogs were captured from forest fragments located in Alfenas-MG and transferred to the laboratory where venom samples were extracted by compressing the paratoid glands. Afterwards, the frogs were kept in the laboratory during three months with an artificial diet consisting of fruit flies and earthworms. During this period, venom samples were extracted after one week and then monthly. The chemical composition of the P. striata ants was also characterized. All the samples were purified and analyzed using a HPLC-UV-MS. Our results showed that chemical composition of the venom was significantly altered after one-week in captivity. Therefore, diet specialization in this species is intimately associated with its poison composition. Furthermore, chemical profiles of the venom and the ant showed distinct substances suggesting that R. ornata sequester and modified substances from their prey.