The chromosome-level genome of Mesobuthus martensii provides insights into its evolution and the diversity of venom peptides

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  The chromosome-level genome of Mesobuthus martensii provides insights into its evolution and the diversity of venom peptides Abstract Mesobuthus martensii , the source species of the traditional Chinese medicine “Quanxie”, has long been utilized for its therapeutic properties. Venom peptides are recognized as the major active molecular basis of these pharmacological activities. Despite this, their development as therapeutic agents remains poorly explored. In this study, we performed an integrated multi-omics investigation to systematically explore the venom peptides of Mesobuthus martensii . We generated a chromosome-level genome assembly of Mesobuthus martensii using third-generation sequencing technologies, yielding a genome size of 1.08 Gb with a contig N50 of 46.46 Mb. Integrated genomic and transcriptomic analyses led to the identification of 51 putative novel venom peptide candidates. From the broader venom peptide set, five lysine- and arginine-rich candidates were select...

Recluse spiders (Araneae: Sicariidae): contesting myths on distribution, bite behavior, and medical risk in Florida

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Recluse spiders (Araneae: Sicariidae): contesting myths on distribution, bite behavior, and medical risk in Florida

Abstract

Recluse spiders are arachnids of potential medical significant due to their necrotic venom. However, in areas populated by the brown recluse, Loxosceles reclusa, bites and necrosis are rare. In Florida, USA, public media reports and medical case studies have propagated three misconceptions about recluse spiders: breeding populations are widespread in Florida, USA; recluse spiders readily bite when encountered; and verified recluse spider bites inevitably produce necrotic wounds. Here, in onsite investigations of 220 Florida properties with alleged infestations of recluse spiders reported to the USDA or the Florida Brown Recluse Project, we found breeding populations of the invasive Mediterranean recluse (L. rufescens) at only 19 sites. In experimental bite assays including non-injurious pressure or pinching to jaws, legs, or abdomen, brown recluse and Mediterranean spiders exhibited negligible bite responses (median = 0%). In contrast, wolf spiders exhibited significant defensive bite responses (median = 80%). Lastly, only one verified bite was reported by an adult female, which did not result in necrosis. In conclusion, our field survey and behavioral assays challenge three long-standing myths specific to Florida. Recluse spiders are scarce. Recluse spiders are reluctant to bite. Recluse spiders are unlikely to account for most necrotic skin wounds attributed to them. In the final analysis, the risk to humans has been overstated, warranting a reevaluation of their role in suspected necrotic lesions by the medical community and the public.

Louis A Coticchio, Deby L Cassill, Recluse spiders (Araneae: Sicariidae): contesting myths on distribution, bite behavior, and medical risk in Florida, Journal of Medical Entomology, Volume 63, Issue 1, January 2026, tjag004, https://doi.org/10.1093/jme/tjag004