Host resistance to ticks (Acari: Ixodidae) in a pit viper, Gloydius tsushimaensis, (Reptilia: Squamata: Viperidae) observed in the field.

Resistance of hosts to ticks has important roles in their interactions. Ticks parasitize not only mammals, but also birds, reptiles and amphibians. Thus, a better understanding of their interaction requires studies of the resistance of various host taxa. We examined the presence of ticks engorged on three species of snakes, Gloydius tsushimaensis, Lycodon rufozonatus and Elaphe climacophora, on Tsushima Islands, Japan in 2017 and 2018. The rate of G. tsushimaensis parasitized by ticks was high (87.5%), but none of those ticks were engorged, and the frequency of live ticks on each snake was low (16.1 ± 5.4%). On the other hand, engorged ticks were found on L. rufozonatus and E. climacophora, and no dead ticks were observed on them. In addition, laboratory observation revealed that two of three ticks that had attached to G. tsushimaensis died within approximately 6 days after attaching, and the third did not engorge. Our results suggest that only G. tsushimaensis among the three snake species on the Tsushima Islands possesses strong host resistance to ticks. Our study suggests that host resistance in snakes may have considerable influence on tick and host populations and on transmission dynamics between them. [ABSTRACT FROM AUTHOR]