Habu vipers (Protobothrops flavoviridis) are an overlooked but important reservoir of the zoonotic tick Amblyomma testudinarium (Acari: Ixodidae) in subtropical Asia.

Subtropical Asia has a rich diversity of reptiles and ticks, though the role of reptiles in the sylvatic cycles of medically important ticks in the region is poorly known. Habu vipers (Protobothrops flavoviridis) are widespread and common in the Japanese subtropics but their role as hosts for ticks has not been carefully explored. For 15 months in 2023/24, habu vipers were screened for ticks and were found to be important hosts for immature stages of the tick Amblyomma testudinarium, with a 22 % infestation rate. Amblyomma testudinarium was found to have weak attachment site preferences on P. flavoviridis and host body length was found to have no relationship with either the risk of infestation or the tick load in infested snakes. The phenological profile of A. testudinarium was mapped for the first time in the subtropics based on mean tick loads on P. flavoviridis and historical flagging data. March-April were identified as the period of highest activity, May to July was a period of declining activity, August-September was a period of almost complete inactivity, and October to February was a periods of increasing activity. The role of habu vipers in the sylvatic cycle of A. testudinarium in subtropical Asia is discussion. Additionally, the potential of habu vipers to serve as reservoirs of pathogens or as dilution hosts is also explored.