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Experimental & applied acarology2025; 95(4); 67; doi: 10.1007/s10493-025-01097-5

Rewilded horses as a nature-based solution for wintertime tick control in Japan: help or hindrance?

Abstract: The control of ticks is challenging owing to their ubiquity, complex ecologies, and difficulties relating to costs and non-target impacts of chemical control programs. Nature-based solutions centre around co-opting natural processes and biodiversity to address socio-environmental problems; and in some cases, rewilded species can provide nature-based solutions. In northern Japan, the winter ecology of ticks is poorly studied, though some species are believed to overwinter under the snow. Winter grazing activity of rewilded horses may disturb overwintering ticks, exposing them to sub-zero temperatures and killing them, thereby providing a nature-based solution to tick control. In this study we sought to ascertain: (i) whether ticks in Japan overwinter in leaflitter under the snow, (ii) whether the winter grazing activity of semi-rewilded horses is associated with reduced springtime tick abundance, (iii) whether semi-rewilded horses serve as key hosts for ticks during springtime. Paired leaflitter sampling undertaken at 10 sites during autumn and winter, respectively, showed that Haemaphysalis ticks overwinter in leaflitter under the snow. Using six paired 25 m exclusion-grazing plots we tested whether winter horse grazing was associated with reduced springtime tick abundances but found no significant relationships. Springtime surveys revealed extremely low tick loads (0.2 ticks per horse) and prevalences (12%) on semi-rewilded horses. This suggests that while the winter grazing activities of horses may not appreciably reduce tick abundances, that horses likely do not serve as important amplifying hosts of ticks in northern Japan and that rewilded horses are neither a help nor hinderance to local tick control efforts in this region.
Publication Date: 2025-12-02 PubMed ID: 41329439PubMed Central: 10788177DOI: 10.1007/s10493-025-01097-5Google Scholar: Lookup
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  • Journal Article

Summary

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Objective Overview

  • This study investigated whether rewilded horses in northern Japan can naturally control tick populations during winter by disturbing their overwintering sites, and whether these horses might also serve as hosts that affect tick abundance in spring.

Background

  • Ticks are widespread and have complex life cycles, making their control difficult and costly.
  • Chemical control methods often produce negative effects on non-target species and the environment.
  • Nature-based solutions aim to harness natural processes and biodiversity to solve environmental problems with fewer side effects.
  • Rewilded species—animals reintroduced or allowed to return naturally to ecosystems—could potentially help control pests like ticks.
  • In northern Japan, the winter behavior and survival of ticks are not well understood, though some ticks are thought to survive under snow cover.
  • It was hypothesized that winter grazing by rewilded horses might disrupt ticks overwintering in leaf litter, exposing ticks to freezing temperatures and reducing their numbers.

Research Questions

  • Do ticks in northern Japan overwinter in leaf litter beneath snow?
  • Is there a connection between winter grazing by semi-rewilded horses and a reduction in tick numbers come spring?
  • Do semi-rewilded horses act as important hosts for ticks during the springtime?

Methodology

  • Leaf litter samples were collected from 10 sites in both autumn and winter to detect presence and survival of Haemaphysalis ticks during overwintering.
  • Six pairs of 25-meter plots were established: one set accessible to horses for grazing and one exclusion plot where horses could not graze, to compare springtime tick abundance.
  • Tick loads on semi-rewilded horses were recorded during spring to assess whether horses were hosting ticks and possibly increasing tick numbers.

Key Findings

  • Haemaphysalis ticks were found to survive overwinter within leaf litter under snow cover, confirming the overwintering habitat.
  • There was no significant difference in springtime tick abundance between grazed plots and exclusion plots, suggesting that winter grazing by horses does not reduce tick populations appreciably.
  • The tick load on semi-rewilded horses was very low (0.2 ticks per horse on average), with only 12% of horses hosting ticks in spring.

Conclusions

  • Winter grazing activity by rewilded horses does not significantly reduce tick abundance in northern Japan.
  • Semi-rewilded horses do not act as major amplifying hosts for ticks during spring, meaning they are unlikely to increase tick populations.
  • Rewilded horses neither substantially help nor hinder efforts to control ticks in this region through natural behavioral means.
  • This suggests that while rewilded horses influence their environment, their role as a nature-based solution for tick control in this context is limited.

Implications and Future Directions

  • Further research could explore other nature-based approaches or different species that might impact tick populations more effectively.
  • Understanding the detailed ecology of ticks in winter remains important, especially regarding other factors that could reduce their survival.
  • Management strategies for tick control in northern Japan may need to combine multiple approaches rather than relying solely on rewilded herbivores.

Cite This Article

APA
Kwak ML, Echigo H, Hoketsu T, Taya Y, Numata H, Shiraki Y, Kelava S, Markowsky G, McInnes D, Hayashi N, Nonaka N, Kawai M, Nakao R. (2025). Rewilded horses as a nature-based solution for wintertime tick control in Japan: help or hindrance? Exp Appl Acarol, 95(4), 67. https://doi.org/10.1007/s10493-025-01097-5

Publication

ISSN: 1572-9702
NlmUniqueID: 8507436
Country: Netherlands
Language: English
Volume: 95
Issue: 4
Pages: 67

Researcher Affiliations

Kwak, Mackenzie L
  • Department of Disease Control, Faculty of Veterinary Medicine, Laboratory of ParasitologyHokkaido University, Sapporo, 060-0818, Hokkaido, Japan. mackenziekwak@gmail.com.
Echigo, Hazuki
  • Graduate School of Global Food Resources, Hokkaido University, Sapporo, 060-0809, Hokkaido, Japan.
Hoketsu, Takaya
  • Department of Disease Control, Faculty of Veterinary Medicine, Laboratory of ParasitologyHokkaido University, Sapporo, 060-0818, Hokkaido, Japan.
Taya, Yurie
  • Department of Disease Control, Faculty of Veterinary Medicine, Laboratory of ParasitologyHokkaido University, Sapporo, 060-0818, Hokkaido, Japan.
Numata, Hideka
  • Department of Disease Control, Faculty of Veterinary Medicine, Laboratory of ParasitologyHokkaido University, Sapporo, 060-0818, Hokkaido, Japan.
Shiraki, Yuto
  • Department of Disease Control, Faculty of Veterinary Medicine, Laboratory of ParasitologyHokkaido University, Sapporo, 060-0818, Hokkaido, Japan.
Kelava, Samuel
  • Department of Disease Control, Faculty of Veterinary Medicine, Laboratory of ParasitologyHokkaido University, Sapporo, 060-0818, Hokkaido, Japan.
Markowsky, Greg
  • School of Mathematics, Monash University, 9 Rainforest Walk, Clayton, VIC, 3800, Australia.
McInnes, Daniel
  • School of Mathematics, Monash University, 9 Rainforest Walk, Clayton, VIC, 3800, Australia.
Hayashi, Naoki
  • Department of Disease Control, Faculty of Veterinary Medicine, Laboratory of ParasitologyHokkaido University, Sapporo, 060-0818, Hokkaido, Japan.
Nonaka, Nariaki
  • Department of Disease Control, Faculty of Veterinary Medicine, Laboratory of ParasitologyHokkaido University, Sapporo, 060-0818, Hokkaido, Japan.
Kawai, Masahito
  • Shizunai Livestock Farm, Field Science Center for Northern Biosphere, Hokkaido University, Shinhidaka, Japan.
Nakao, Ryo
  • Department of Disease Control, Faculty of Veterinary Medicine, Laboratory of ParasitologyHokkaido University, Sapporo, 060-0818, Hokkaido, Japan.
  • Division of Parasitology, Veterinary Research Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, 060-0818, Hokkaido, Japan.
  • One Health Research Center, Hokkaido University, Sapporo, Japan.

MeSH Terms

  • Animals
  • Japan
  • Horses / physiology
  • Seasons
  • Tick Control / methods
  • Ixodidae / physiology
  • Herbivory
  • Horse Diseases / parasitology
  • Horse Diseases / prevention & control
  • Tick Infestations / veterinary
  • Tick Infestations / prevention & control
  • Tick Infestations / parasitology
  • Tick Infestations / epidemiology

Grant Funding

  • JP23wm0225034 / Japan Agency for Medical Research and Development

Conflict of Interest Statement

Declarations. Competing interests: We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome. Ethical approval: No experiments were performed on live animals or human subjects and all ethical guidelines for research in Japan were adhered to.

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