Beyond Venom and Constriction: Bite Performance and Trophic Ecology in the Genus Drymarchon

Posted by
  Beyond Venom and Constriction: Bite Performance and Trophic Ecology in the Genus Drymarchon Abstract Snakes exhibit extreme cranial kinesis that facilitates ingestion of prey with large cross-sectional area, but this ability is widely predicted to reduce bite performance due to decreased structural rigidity. Consequently, most large-bodied snakes rely on envenomation or constriction to subdue prey prior to ingestion. Species within the genus Drymarchon represent a notable exception: these large, non-venomous, non-constricting snakes routinely consume a wide range of prey, including large and potentially dangerous vertebrates, using only simple seizing and pinioning behaviors. Here, we quantify bite performance in three species of Drymarchon ( D. corais, D. couperi, and D. melanurus ), examine morphological predictors of biting performance, compare biting pressure to constriction pressure in similarly sized snakes, and synthesize dietary records across the genus. Our results sh...

Evaluation of the therapeutic window of commercial antivenoms against neurotoxicity induced by Bungarus ceylonicus and Bungarus caeruleus venoms in the chick-biventer cervicis model

Posted by

 


Evaluation of the therapeutic window of commercial antivenoms against neurotoxicity induced by Bungarus ceylonicus and Bungarus caeruleus venoms in the chick-biventer cervicis model

Abstract

Krait (Genus: Bungarus) envenoming is characterised by progressive neuromuscular paralysis. In Sri Lanka, the absence of a species-specific antivenom for envenoming by the endemic Sri Lankan krait (Bungarus ceylonicus) necessitates reliance on Indian polyvalent antivenoms, despite limited evidence of their efficacy. This study investigated the time window during which commercial Indian (BHARAT, VINS) and Australian polyvalent (Seqirus) antivenoms can prevent neurotoxicity induced by Sri Lankan Krait (B. ceylonicus) and Common Krait (Bungarus caeruleus) venoms using the chick biventer cervicis nerve–muscle preparation. Venoms were added at concentrations producing either predominantly pre-synaptic or post-synaptic neurotoxicity, and antivenoms were added 30 or 90 min after venom exposure. When added after venom, all antivenoms showed a consistent, time-dependent decline in efficacy against pre-synaptic neurotoxicity, with only partial prevention when added after 30 min and complete failure when added after 90 min. In contrast, post-synaptic neurotoxicity remained more amenable to neutralisation after a delay; BHARAT partially prevented post-synaptic effects of both venoms at 30 min, while VINS fully prevented post-synaptic neurotoxicity of B. caeruleus at the same time point. These findings support the hypothesis that pre-synaptic toxins rapidly enter motor nerve terminals, limiting antivenom access and reversibility, whereas the effects of post-synaptic toxins are more readily reversible due to their extracellular mode of action.
Galappaththige, J., Hodgson, W. C., Maduwage, K., Isbister, G. K., & Silva, A. (2026). Evaluation of the therapeutic window of commercial antivenoms against neurotoxicity induced by Bungarus ceylonicus and Bungarus caeruleus venoms in the chick-biventer cervicis model. Toxicon, 109258. https://doi.org/10.1016/j.toxicon.2026.109258