Thermal ecology of Plesiopelma longisternale: novel insights and comparative analysis with a sympatric species

Posted by
  Thermal ecology of Plesiopelma longisternale: novel insights and comparative analysis with a sympatric species Abstract Understanding thermal responses in ectotherms is key to assessing vulnerability to climate change. Tarantulas (Theraphosidae) are informative models due to their sedentary lifestyle, long life cycles, and reliance on specific microhabitats. We present the first integrative assessment of the thermal ecology of Plesiopelma longisternale , a widespread Argentine species, combining experimentally derived thermal limits and thermal preferences with species distribution models, and compare its thermal profile with the sympatric Grammostola vachoni to explore patterns of thermal niche differentiation. Plesiopelma longisternale showed a minimum thermal limit near 4 °C, a maximum near 44 °C, a thermal optimum of 29.5 °C, a narrow thermal performance breadth, and a preferred temperature of approximately 32 °C. Models integrating climatic and thermal parameters predicted...

Paralysis Efficiency (PD50) Scales Linearly with Lethality (LD50) in Spider Venoms

Posted by

 


Paralysis Efficiency (PD50) Scales Linearly with Lethality (LD50) in Spider Venoms

Abstract

Historically, venom potencies have been assessed using measures of lethality, such as the median lethal dose (LD50). However, venoms may be selected primarily for their ability to rapidly incapacitate rather than cause mortality, meaning LD50 may not capture the efficacy of venoms in an ecological and evolutionary context. To capture this context, recent studies have adapted measures that assess venoms’ ability to rapidly incapacitate, such as the median paralysis dose (PD50). However, while PD50 values are expected to provide a more proximate assessment of ecological variation in venom potency, it is unknown whether historically available LD50 values are still useful proxies of ecologically relevant potency or whether they capture independent axes of venom variation. Here, we test the relationship between LD50 and PD50 in spider venoms by experimentally estimating LD50 and PD50 for 12 species and collating additional potency data for 46 species retrieved from the literature, producing a dataset of 55 species spanning 26 families when combined. We observed a linear isometric relationship between LD50 and PD50, showing these potency measures are both strongly correlated, with an increase in paralysis efficiency associated with a similar increase in lethality. Our results suggest that due to the correlation between functional aspects of venom potency, paralysis and lethality, historically available LD50 values may be used to compare general venom potencies in spiders, provided that they are based on the same prey model.
Lyons, K., Leonard, D., McSharry, L., Martindale, M., Collier, B. L., Vitkauskaite, A., Dunbar, J. P., Dugon, M. M., & Healy, K. (2026). Paralysis Efficiency (PD50) Scales Linearly with Lethality (LD50) in Spider Venoms. Toxicon: X, 100256. https://doi.org/10.1016/j.toxcx.2026.100256