2001 Volume 10 Issue 1 Pages 1-17
In the Ryukyu Islands of southern Japan, we examined the ticks and mites parasitic on the body surface of sea snakes belonging to the subfamilies Hydrophiinae (Emydocephalus ijimae, Hydrophis melanocephalus and H. ornatus) and Laticaudinae (Laticauda semifasciata, L. laticauda and L. colubrina). the tick, Amblyomma nitidum, and three species of trombiculid mites were found only from Laticaudinae sea snakes. The % snakes infested by larvae, nymphs and adults of A. nitidum ranged 0-95.0%, 0-55% and 0-20.0%, respectively. Larvae and nymphs infested more intensively in warmer seasons. Frequency distributions of the number of ticks per host showed that they were not distributed randomly but clumped. Replete larvae detached from the hosts in the daytime more frequently (not examined for replete nymphs and adults). This temporal drop-off pattern results in ticks remaining in the resting sites of the hosts because the hosts usually swim at night but rest in crevices of shore rocks in the daytime, No larvae or nymphs died even when placed in artificial seawater for 24 hours in the laboratory. The infection rates of the trombiculid mites, tentatively called spp. t, w, and b in this paper, ranged 0-34.6%, 0-50.0%, and 0-25.0%, respectively. In total, 62,5% of hosts were infested by a single mite species, and 37.5% by two or three species. Similarly to the tick A. nitidum, these mites had clumped distribution patterns and diurnal drop-off rhythms after engorgement, although the latter was examined only for sp. t.
