Harvestmen (Arachnida: Opiliones) as Overlooked Predators of Anurans in the Neotropics

Posted by
  Harvestmen (Arachnida: Opiliones) as Overlooked Predators of Anurans in the Neotropics ABSTRACT Arthropods are traditionally viewed as invertebrate prey and as predators of other invertebrates, whereas vertebrates are typically considered their predators. However, this paradigm has increasingly been challenged, particularly among arachnids. While several invertebrates are well documented as frog predators, the capacity of particular groups, such as harvestmen (Opiliones), to prey on vertebrates has remained largely anecdotal. Here we report novel field observations of anuran predation by multiple Cranaidae harvestman species across several Neotropical localities. These records include the active capture and consumption of live frogs, demonstrating their role as opportunistic mesopredators. Our findings expand current knowledge of Opiliones ecology by confirming that vertebrate predation occurs across multiple species and localities. Our results suggest that vertebrate consumption...

Tityus paraguayensis, a scorpion from the Brazilian Cerrado: first assessment of venom and hemolymph composition and biological activity

Posted by

 


Tityus paraguayensis, a scorpion from the Brazilian Cerrado: first assessment of venom and hemolymph composition and biological activity

Abstract

Scorpionism is a serious public health problem in Brazil, where scorpion stings are the most frequent accidents caused by venomous animals. Scorpion venoms comprise a complex mixture of different classes of molecules, some of which may possess pharmacological properties. This study aimed to investigate the biological activity and composition of the venom and hemolymph of Tityus paraguayensis, an endemic species found in Mato Grosso do Sul State. The hemolymph showed proteolytic and lipase activities associated with innate immunity and digestive processes, respectively. Although these activities are not believed to be involved in the manifestations of envenomation, they might prove valuable in the prospection of compounds with antimicrobial activity. The venom exhibited phospholipase and lipase activities and stimulated (Na+,K+)-ATPase activity. The venom was also analyzed for activity against epimastigote forms of Trypanosoma cruzi. In this assay, T. paraguayensis venom inhibited parasite growth. The venom did not cause cytotoxicity to Vero cells. SDS-PAGE analysis revealed proteins ranging from 10 to 140 kDa, as well as bands with molecular mass <10 kDa, possibly corresponding to neurotoxic peptides. HPLC analysis of T. paraguayensis venom revealed that the highest number of peaks had retention times of 1 to 20 min (0 to 35% acetonitrile). The partial sequence of peak 10 was determined by Q-TOF analysis and was partially identified as a peptide (Tp10) that possible act as a K+ channel ligand (KTx). Additionally, 5 toxins related to potassium channel toxins, 3 toxins related to sodium channel toxins and a metalloproteinase were identified by shotgun proteomic of T. paraguayensis venom . This is the first report of the biological activities, HPLC profile, electrophoretic pattern and proteomic analysis of T. paraguayensis venom. These findings suggest that T. paraguayensis venom may be a valuable source for the identification of molecules with pharmacological applications.
Covali-Pontes, H. R., Lima Fernandes, M. M., Corrêa de Lima, L., Rodrigues Macedo, M. L., Giannesi, G. C., Bastos de Oliveira, M. A., Teixeira Ferreira, A. M., Farias Frihling, B. E., Migliolo, L., Pereira dos Santos, N. G., Abreu Falla, M. V., Coelho, G. R., & Neilson de Lucena, M. (2025). Tityus paraguayensis, a scorpion from the Brazilian Cerrado: First assessment of venom and hemolymph composition and biological activity. Toxicon, 108332. https://doi.org/10.1016/j.toxicon.2025.108332 or https://www.sciencedirect.com/science/article/pii/S0041010125001060