Climatic and density-dependent drivers of population dynamics in a hazardous urban scorpion species over seven years

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  Climatic and density-dependent drivers of population dynamics in a hazardous urban scorpion species over seven years Abstract This link goes to a Portuguese section Tityus serrulatus Lutz & Mello (Scorpiones: Buthidae) is the most medically important scorpion in Brazil, responsible for a growing number of accidents in urban areas. Despite its relevance, the population dynamics of this species in anthropogenic habitats remain poorly understood, particularly regarding the influence of abiotic factors on its abundance and reproduction. We analysed long-term data (2006–2013) from T. serrulatus collected in an urban cemetery in the municipality of Americana, São Paulo State, Brazil. Using spatiotemporal mixed models, we evaluated the effects of temperature and humidity at the graves on the abundance of brooded and non-brooded individuals, as well as on the ratio between the two reproductive groups. A total of 21,489 individuals were recorded, including 463 brooded individuals. W...

Digestion in the arachnid Mischonyx squalidus as a probable source of lipids to synthesize opiliones defense and communication molecules

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Digestion in the arachnid Mischonyx squalidus as a probable source of lipids to synthesize opiliones defense and communication molecules

Abstract

Opiliones (Arachnida) comprises approximately 7,000 species. Due to their lack of venom glands, their defense is mainly based on the secretion of scent glands, which also play roles in communication and antimicrobial activity. This odoriferous secretion has a diverse composition according to harvestmen species but frequently contains benzoquinones. Studies of benzoquinone synthesis intermediates suggest a pathway based on lipid metabolism from diet. This study provides the first transcriptomic and enzymatic analysis of the midgut of Mischonyx squalidus to understand the acquisition of nutrients. The enzymatic analysis tested 11 digestive enzymes and found high lipase activity and moderate and low activity for peptidases and carbohydrases, respectively. Transcriptome sequencing yielded 19,658 unigenes, predominating enzymes and binding proteins closely associated with Xiphosura and Scorpiones proteins; a third of which are hydrolases. A multigene lipase family is expressed. Cathepsin L peptidases were prominently abundant, indicating their relevance for protein digestion. Additionally, toxin-like proteins and lipid metabolism-related enzymes, such as phospholipase A2 and NPC cholesterol transporters, were represented, indicating a sophisticated digestive and metabolic system for lipids. These findings suggest a link between lipid digestive metabolism and defensive and communicative molecule synthesis, underscoring Opiliones’ unique evolutionary adaptations.

Silva, J. O., Viala, V. L., Dias, R. O., Ferreira, C., Terra, W. R., & Lopes, A. R. (2025). Digestion in the arachnid Mischonyx squalidus as a probable source of lipids to synthesize opiliones defense and communication molecules. Scientific Reports, 15(1), 1-15. https://doi.org/10.1038/s41598-025-18180-x