Toxicity of Venom from a Japanese Pitviper (Gloydius blomhoffii) to Centipedes

Hamanaka, Kyosuke

kyo@ethol.zool.kyoto-u.ac.jp

Mori, Akira Department of Zoology

Graduate School of Science

Kyoto University

Kyoto, Japan

Most vipers usually feed on vertebrates, but several species of rattlesnakes and pit vipers sometimes eat centipedes. Centipedes have been also found occasionally in stomach contents of a Japanese pit viper, Gloydius blomhoffii. Like many other vipers, G. blomhoffii usually injects its venom to prey animals to kill or incapacitate them before eating. Toxicity of the venom of G. blomhoffii to mammals has been well studied, but there is no information concerning its toxicity to centipedes. Here, we studied the toxicity to the Red-headed Centipede, Scolopendra subspinipes, by comparing with the toxicity to two other common prey animals; House Mouse (Mus musculus) and Pond Frog (Pelophylax nigromaculatus). To evaluate the toxicity of the venom that is actually injected to prey animals when snakes strike them in the wild, the injection was carried out using raw venom collected from fangs, and mortality rate three hours after injection was examined. The lethal doses for mice weighing around 21.5 g and frogs weighing around 3.8 g were both less than 5 µl, which corresponds to an estimated dose of one envenomation by G. blomhoffii. On the other hand, centipedes weighing 0.8–3.2 g needed 10–35 µl of the venom to die. There was no significant correlation between the lethal dose and their body mass. Our results indicate that it is difficult for G. blomhoffii to kill or incapacitate centipedes by a single envenomation. Thus, G. blomhoffii may eat centipedes in a way different from that for eating mice and frogs.