New Insight Into the Evolutionary Arms Race Between Spider Egg Sac Pseudoparasitoids and Active Maternal Care by the Spiders

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  New Insight Into the Evolutionary Arms Race Between Spider Egg Sac Pseudoparasitoids and Active Maternal Care by the Spiders ABSTRACT Pseudoparasitoids can lead to high mortality in spider egg sacs, and in some cases, they reduce the reproductive success of a spider female to zero. On the other hand, a species that develops within the spider's egg sac uses a limited resource derived from a single egg sac for its larval development. Therefore, the most crucial behaviour that increases the fitness of free-living pseudoparasitoid females is choosing the best host for their offspring. We analysed various points of the counter-adaptations of the spider egg sac pseudoparasitoid and spiders exhibiting active maternal care, utilising the ichneumonid  Hidryta fusiventris  (Thomson, 1873) and the wolf spider  Pardosa lugubris  (Walckenaer, 1802). We showed that the oviposition decision of  H. fusiventris  is based on the spider's egg sac size and that the fema...

Hyaluronidase activity of Indian ornamental tarantula (Poecilotheria regalis) venom is significantly reduced by commercial Latrodectus mactans and American scorpion antivenoms

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Hyaluronidase activity of Indian ornamental tarantula (Poecilotheria regalis) venom is significantly reduced by commercial Latrodectus mactans and American scorpion antivenoms

Abstract

A recent clinical case involving a Poecilotheria regalis bite was treated with Mexican L. mactans antivenom (Aracmyn Plus, Silanes, Mexico), resulting in the improvement of some of the symptoms. This could be attributed to cross-reactivity caused by structural similarities between certain components of L. mactans and P. regalis venoms. The aim of the present study was to evaluate the cross-reactivity of P. regalis venom with commercial antivenoms that target the venom of the Latrodectus mactans spider and American scorpions. Hyaluronidase activity was evaluated via a turbidimetric method, while edema was evaluated in rat paw via a histopathological analysis. Cross-reactivity was determined using SDS-PAGE and western blotting. The results obtained showed that both antivenoms significantly reduced the hyaluronidase activity of P. regalis venom and that induced by other tarantula venoms. Aracmyn Plus did not reduce inflammation caused by P. regalis venom. Furthermore, it was previously observed that this antivenom failed to reduce the characteristic muscle cramps induced by this venom. Finally, western blotting revealed that both antivenoms showed cross-reactivity with P. regalis venom. The above findings suggest that hyaluronidases and other high-molecular-weight components exhibit structural similarities across the venoms from different arachnid species.
García-García, M., Mosqueda, J., Escobar-Cabrera, J. E., Murillo-Maldonado, J. M., & José Alejandro, G. (2025). Hyaluronidase activity of Indian ornamental tarantula (Poecilotheria regalis) venom is significantly reduced by commercial Latrodectus mactans and American scorpion antivenoms. Toxicon, 108543. https://doi.org/10.1016/j.toxicon.2025.108543