Meeting Abstract
Black widow spiders (Latrodectus) have evolved a potent venom (Latrotoxin, or LTX) that is effective against a wide range of prey, including small vertebrates. While the effects of LTX on mammals are well understood, the effects on reptiles have never been investigated. Lizards are often major predators of spiders, and at least two lizard species (Elgaria multicarinata and Sceloporus occidentalis are broadly syntopic with, and prey upon, Latrodectus in the western US. We sought to determine whether these lizards possess resistance to LTX. We assessed resistance in E. multicarinata, S. occidentalis, and a third lizard species known to be eaten by black widows (Uta stansburiana) through whole-animal performance trials and tissue histology. We obtained baseline sprint speeds, then injected lizards with low (1 mouse LD50) and high (5 mouse LD50) mass-adjusted venom dose treatments. Control animals received injections of saline, and we obtained post-injection sprint speeds from all groups. Following these whole animal trials, we harvested tissue from injection sites for histological examination. We found no statistical decrease in sprint speed between control and treatment groups, though we detected a potential decrease in sprint speed for U. stansburiana at the high venom dose. Although the histologic examination is still in progress, we saw evidence for some susceptibility in U. stansburiana, while both E. multicarinata and S. occidentalis appear resistant to the venom of their dangerous spider prey. These data suggest that the predator-prey relationships between some lizards and their spider prey may be more complex than previously imagined, and potentially involve a number of physiological and molecular adaptations that allow lizards to cope with potent arachnid venoms.
