Selective Parasitism of the Tick Ixodes asanumai (Acarina : Ixodidae) and Its Influence on the Host Lizard Eumeces okadae in Miyake-jima, Izu Islands

Abstract

The tick Ixodes asanumai parasitic on the lizard Eumeces okadae, showed a selective parasitism in respect of the size and sex of hosts and the attachment site for blood-sucking. In Miyake-jima, 21.0% of lizards were on the average infested by female ticks. Mature male lizards received the most intensive infestation, probably because of their high activity in the mating season. On the average, 67, 9%and 22.4% of lizards were infested by larval and nymphal ticks, respectively. In all stages of ticks, the infestation level increased with the lizard size. Almost all female ticks selectively attacheced on the knee of lizard's forelegs. In contrast, the larval ticks generally attached on the toe of legs and nymphs on the trunk. This stage specific selection of attrachment sites was reconfirmed by the feeding experiment under the laboratory conditions. The histological observation revealed that the female tick parasitism caused the atrophy of muscle fibers of the lizard's foreleg.