マダニが異常気温に強いことを証明する(Ticks prove resilient to extreme temperatures)

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2023-06-01 ワシントン州立大学(WSU)

◆最新の研究では、ブラックレッグド・ダニ(Ixodes scapularis)が極端な寒暑にも耐えられることが明らかになりました。成虫と若虫は乾燥や熱にほとんど影響を受けずに生き延びることができます。
◆この発見は、ライム病の広がりに関する洞察を提供し、ダニ媒介の病原体のリスクを軽減するための戦略開発に役立つ可能性があります。将来の研究では、ダニの生息に影響を与える要素や寄主種の役割をさらに探求する予定です。

<関連情報>

北アメリカ東部におけるクロアシカツオダニの宿主外生存率: 多段階、多年度、多拠点での研究 Off-host survival of blacklegged ticks in eastern North America: A multistage, multiyear, multisite study

Jesse L. Brunner, Shannon L. LaDeau, Mary Killilea, Elizabeth Valentine, Megan Schierer, Richard S. Ostfeld
Ecological Monographs  Published: 30 March 2023
DOI:https://doi.org/10.1002/ecm.1572

Details are in the caption following the image

Abstract

Climatic conditions are widely thought to govern the distribution and abundance of ectoparasites, such as the blacklegged tick (Ixodes scapularis), vector of the agents of Lyme disease and other emerging human pathogens. However, translating physiological tolerances to distributional limits or mortality is challenging. Ticks may be able to avoid or tolerate unsuitable conditions, and what is lethal to one life history stage may not extend to others. Thus, even after decades of research, there are clear gaps in our knowledge about how climatic conditions determine tick distributions or patterns of abundance. We present results from a 3-year study combining daily hazard models and data from field experiments at three sites spanning much of I. scapularis‘ current latitudinal distribution. We examine three predominant hypotheses regarding how temperature and vapor pressure deficits affect stage-specific survival and transition success and consider how these results influence population growth and distribution. We found that larvae are sensitive to temperature and vapor pressure deficits, whereas mortality of nymphs and adults is consistent with depletion of energy reserves. Consistent with prior work, we found that overwinter survival was high and successful stage transitions (e.g., fed nymphs molting to adults) were sensitive to temperature. Collectively, results from this comprehensive, multiyear, multistage field study suggest that population growth of I. scapularis is less limited by restrictive climatic conditions than has been broadly assumed, although influences on larval survival may slow tick population growth and establishment in some desiccating conditions. Further studies should integrate climate effects on stage-specific survival to better understand these effects on population dynamics and range expansion in a changing climate.

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