Seasonality, Moisture, and Host Community Structure of Haemaphysalis Ticks in a Subtropical Urban Mosaic in Hong...

Ticks (Ixodida) are ecologically and epidemiologically important parasites, yet their diversity, host associations, and environmental drivers remain poorly resolved in many parts of the world, including subtropical and urban Hong Kong. Here, we combined wet-season spatial surveys (23 sites in 2023) with monthly temporal sampling (four sites across 11 months in 2024) to characterize the spatiotemporal dynamics of ticks in Hong Kong. Ticks were collected using standardized drags, CO² traps, and opportunistic sampling; adults were identified morphologically and validated via COI barcoding. Vertebrate host use was inferred through iDNA metabarcoding of tick abdomens. Our findings provide the first documented widespread occurrence of Haemaphysalis hystricis and Haemaphysalis formosensis in Hong Kong. Additionally, we provide initial insights into local life stage-specific seasonality dynamics, whereby adult peaks in late winter-spring, nymphs are elevated in the cool dry months, and larvae noticeably surge during the wet season. In assessing the potential environmental drivers, adult abundance was most strongly associated with moisture (relative humidity and dew point). Presence-only models suggested additional contributions from porcupine (Hystrix spp.) occurrence and temperature. iDNA analysis suggests primarily mammalian host feeding (73.7%), specficially wild boar (Sus spp.) and porcupines being the most frequent (43.4%), with additional detections of civets, dogs, cattle, and several bird families. In general, H. hystricis exhibited a broader host spectrum than H. formosensis. Overall, these results indicate that moisture availability and mammal host communities influence Haemaphysalis tick distributions across Hong Kong's mosaic landscape. Future consideration should be made for expanding spatial and temporal surveillance, integrating microhabitat moisture and host density data, and coupling ecological surveys with pathogen screening to inform One Health surveillance and management.