Miguel Eve, Boulinier Thierry, de Garine-Wichatitsky Michel, Caron Alexandre, Fritz Hervé, Grosbois Vladimir
Cirad-ES,AGIRs, (Animal et Gestion Intégrée des Risques/Animal and Integrated Risk Management), Montpellier, France; CNRS-Centre d'Ecologie Fonctionnelle et Evolutive - UMR 5175, Montpellier, France; Cirad-ES, AGIRs-RP-PCP, Harare P.O. Box 1378, Zimbabwe.
CNRS-Centre d'Ecologie Fonctionnelle et Evolutive - UMR 5175, Montpellier, France.
Acta Trop. 2014 Oct;138:5-14. doi: 10.1016/j.actatropica.2014.05.019. Epub 2014 Jun 4.
The sharing of habitat by wild and domestic animals may result in pathogen transmission, notably via ectoparasite vectors such as ticks. Interfaces between protected and communal lands constitute sharp transitions between areas occupied by host communities that are extremely contrasted in terms of composition, diversity and density. Empirical characterizations of tick communities and of their vertebrate hosts are strongly relevant for understanding the mechanisms leading to disease transmission between wild and domestic animals. In the present study we aimed at depicting the pattern of spatial variation in the density of immature ticks at such an interface located in Zimbabwe. At the end of the 2011 rainy season, we applied a hierarchical repeated protocol to collect ticks. We used the drag-sampling method in the vegetation surrounding water pans used by ungulates in 3 distinct landscape compartments (i.e. national park, mixed compartment and communal lands) characterized by a differential use by wild and domestic hosts. We combined generalized linear mixed models with site occupancy models to (1) assess tick aggregation levels at different spatial scales, (2) identify and disentangle factors which influence the density and probability of tick detection, and (3) compare robust estimations of tick densities among the landscape compartments. Ticks belonging to the Amblyomma and Riphicephalus genuses were found to be the most abundant. At small scale, ticks were more often detected in the afternoon and were more abundant close to water pans for Amblyomma and Riphicephalus genuses. Riphicephalus spp. density was also higher in grassland and bushland vegetation types as compared to woodland vegetation type. At large scale, for the three detected genuses, density was much higher near water pans located in the communal lands as compared to the national park and mixed compartment. Given that host community's diversity is much lower in the communal areas than in the two other landscape compartments, these results are compatible with a dilution effect but not sufficient to demonstrate this effect without additional studies. Up to date, it is the first utilization of these rigorous sampling and statistical modelling methodologies to estimate tick density in African ecosystem simultaneously at large and small scales.
野生动物与家畜共享栖息地可能会导致病原体传播，尤其是通过蜱等外寄生虫媒介传播。保护区与公共土地之间的边界构成了宿主群落占据区域之间的急剧过渡，这些区域在组成、多样性和密度方面存在极大差异。蜱类群落及其脊椎动物宿主的实证特征对于理解野生动物与家畜之间疾病传播的机制具有重要意义。在本研究中，我们旨在描绘位于津巴布韦的这样一个边界处未成熟蜱密度的空间变化模式。在2011年雨季结束时，我们采用分层重复方案来采集蜱。我们在有蹄类动物使用的水盘周围的植被中采用拖网采样法，该区域位于3个不同的景观区域（即国家公园、混合区域和公共土地），其特点是野生动物和家畜宿主的使用情况不同。我们将广义线性混合模型与位点占有率模型相结合，以（1）评估不同空间尺度下蜱的聚集水平，（2）识别并厘清影响蜱检测密度和概率的因素，以及（3）比较各景观区域蜱密度的稳健估计值。发现属于钝缘蜱属和璃眼蜱属的蜱最为丰富。在小尺度上，蜱在下午更常被检测到，对于钝缘蜱属和璃眼蜱属来说，在靠近水盘的地方更为丰富。与林地植被类型相比，璃眼蜱属在草地和灌木丛植被类型中的密度也更高。在大尺度上，对于检测到的三个属，与国家公园和混合区域相比，公共土地中水盘附近的密度要高得多。鉴于公共区域宿主群落的多样性远低于其他两个景观区域，这些结果与稀释效应相符，但在没有进一步研究的情况下不足以证明这种效应。迄今为止，这是首次利用这些严格的采样和统计建模方法在非洲生态系统中同时在大尺度和小尺度上估计蜱的密度。
