Questing Height of Haemaphysalis megaspionosa Saito, 1969 (Acari: Ixodidae) is Influenced by Developmental Stages and Relative Humidity

Haemaphysalis megaspinosa Saito, 1969, is a three-host tick species that employs an 'ambush strategy' when questing host animals for vegetation. This strategy involves adjusting the questing height to align with the body size of potential hosts, thereby facilitating external parasitism. The questing height of ticks varies across developmental stages, and while physiological theories suggest that immature ticks are more susceptible to desiccation due to their thinner exoskeletons, empirical evidence directly linking developmental stage, questing height, and environmental conditions remains limited across tick species. We examined how questing height differs according to developmental stage and how it is influenced by environmental conditions (temperature, relative humidity, and soil moisture) and host body size. Our analysis revealed a significant positive association between questing height, developmental stage, and relative humidity. In larvae and nymphs, the questing height increased with relative humidity, indicating that these stages adjusted their positioning in response to humidity levels. In contrast, the questing height of adults remained largely unaffected by relative humidity and was predominantly observed within the estimated possible range of adhesion for large mammals such as sika deer (Cervus nippon Temminck, 1836) and wild boar (Sus scrofa Linnaeus, 1758). These findings suggest that the response of tick-questing behavior to environmental conditions varies by developmental stage, influencing host selection in ticks using the ambush strategy.