Microbiome diversity in Haemaphysalis flava (life stage-host dependent) and Haemaphysalis longicornis ticks with zoonotic implications in Nantong, China.

PURPOSE

This study characterized the microbial communities of Haemaphysalis flava (H. flava) and Haemaphysalis longicornis (H. longicornis), in Nantong, China, and assessed the zoonotic implications.

METHODS

We collected both on-host and off-host ticks and performed 16S rRNA amplicon sequencing. Subsequent bioinformatic analyses included taxonomic composition assessment, community diversity evaluation, differential abundance analysis, interspecies abundance correlation and functional inference.

RESULTS

Rickettsia dominated in H. flava (77.31%), while H. longicornis exhibited higher abundances of Stenotrophomonas (10.78%), Coxiella (10.04%), and Psychrobacter (9.70%). Comparative analyses of life stages and host associations were only performed for H. flava due to limited sample sizes of H. longicornis across developmental stages. Rickettsia was enriched in on-host H. flava (90.41-90.51%) compared to off-host specimens (46.12%). α-diversity analysis showed higher microbial richness in off-host nymphs than in on-host adults. β-diversity revealed strong species-specific clustering. Network analysis demonstrated more complex microbial interactions in adult ticks. Pathogen screening detected Rickettsia japonica (R. japonica, host-specific to H. flava), Ehrlichia ewingii (E. ewingii), and Anaplasma bovis (A. bovis). Functional prediction highlighted elevated B vitamin biosynthesis pathways in nymphs, aligning with Coxiella-like endosymbionts (CLEs)'s putative nutritional role.

CONCLUSION

This study emphasizes the importance of enhanced tick surveillance and regular pathogen screening in domestic animals, particularly for spotted fever group (SFG) Rickettsia. CLEs may exhibit stage-specific abundance patterns aligned with the host's developmental nutritional requirements. These findings highlight the need for integrated One Health surveillance to mitigate tick-borne disease threats.