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

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  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...

Synthesis of U-theraphotoxin-Pv1a_1, an Aedes aegypti larvicidal disulfide bridged peptide from the Colombian tarantula Pamphobeteus verdolaga (Araneae: Theraphosidae)

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Synthesis of U-theraphotoxin-Pv1a_1, an Aedes aegypti larvicidal disulfide bridged peptide from the Colombian tarantula Pamphobeteus verdolaga (Araneae: Theraphosidae)

ABSTRACT

The attention to the increased resistance of Aedes aegipty to traditional insecticides has been directed to the development of bioinsecticides, such as those produced by insect predators, e.g. spiders. Here we present the solid-phase synthesis of native U-theraphotoxin-Pv1a_1 (n-Pv1a_1) from Pamphobeteus verdolaga, an active (by contact) insecticidal peptide against A. aegipty. U-theraphotoxin-Pv1a_1 sequence was gathered from venom proteomics and venom gland transcriptomics of Pamphobeteus verdolaga, and synthesized by solid phase using the Fmoc strategy followed by dimethyl sulfoxide promoted native disulfide bond formation. The synthetic peptide (s-Pv1a_1) was assayed for larvicidal activity in II and III instar A. aegypti larvae, as well as for cytotoxicity in human red blood and HaCat cells. s-Pv1a_1 showed potent activity towards A. aegypti larvae in the micro molar range, while showing no hemolytic activity and mild cytotoxicity to HaCat cells. Its potent contact activity makes n-Pv1a_1 and its synthetic version, s-Pv1a, promising biopesticides for the control of mosquito populations.

Estrada-Gómez, S., Salinas-Restrepo, C., Vargas Muñoz, L. J., Guzmán, F., Latorre, C. S., Pla, D., Sanz, L., & Calvete, J. (2025). Synthesis of U-theraphotoxin-Pv1a_1, an Aedes aegypti larvicidal disulfide bridged peptide from the Colombian tarantula Pamphobeteus verdolaga (Araneae: Theraphosidae). Toxicon: X, 100224. https://doi.org/10.1016/j.toxcx.2025.100224