Abdu Salamatu, Chimento Michael, Alarcón-Nieto Gustavo, Zúñiga Daniel, Aplin Lucy M, Farine Damien R, Brandl Hanja B
Department of Biology University of Konstanz Constance Germany.
Department of Collective Behaviour Max Planck Institute of Animal Behavior Radolfzell Germany.
Ecol Evol. 2022 Aug 23;12(8):e9242. doi: 10.1002/ece3.9242. eCollection 2022 Aug.
Parasites can impact the behavior of animals and alter the interplay with ecological factors in their environment. Studying the effects that parasites have on animals thus requires accurate estimates of infections in individuals. However, quantifying parasites can be challenging due to several factors. Laboratory techniques, physiological fluctuations, methodological constraints, and environmental influences can introduce measurement errors, in particular when screening individuals in the wild. These issues are pervasive in ecological studies where it is common to sample study subjects only once. Such factors should be carefully considered when choosing a sampling strategy, yet presently there is little guidance covering the major sources of error. In this study, we estimate the reliability and sensitivity of different sampling practices at detecting two internal parasites- and sp.-in a model organism, the great tit . We combine field and captive sampling to assess whether individual parasite infection status and load can be estimated from single field samples, using different laboratory techniques-McMaster and mini-FLOTAC. We test whether they vary in their performance, and quantify how sample processing affects parasite detection rates. We found that single field samples had elevated rates of false negatives. By contrast, samples collected from captivity over 24 h were highly reliable (few false negatives) and accurate (repeatable in the intensity of infection). In terms of methods, we found that the McMaster technique provided more repeatable estimates than the mini-FLOTAC for eggs, and both techniques were largely equally suitable for oocysts. Our study shows that field samples are likely to be unreliable in accurately detecting the presence of parasites and, in particular, for estimating parasite loads in songbirds. We highlight important considerations for those designing host-parasite studies in captive or wild systems giving guidance that can help select suitable methods, minimize biases, and acknowledge possible limitations.
寄生虫会影响动物的行为，并改变它们与环境中生态因素的相互作用。因此，研究寄生虫对动物的影响需要准确估计个体的感染情况。然而，由于多种因素，对寄生虫进行量化可能具有挑战性。实验室技术、生理波动、方法学限制和环境影响都可能引入测量误差，尤其是在对野外个体进行筛查时。这些问题在生态研究中普遍存在，在这类研究中，通常只对研究对象进行一次采样。在选择采样策略时，应仔细考虑这些因素，但目前几乎没有涵盖主要误差来源的指导意见。在本研究中，我们估计了不同采样方法在检测一种模式生物大山雀体内两种体内寄生虫（和种）时的可靠性和灵敏度。我们结合野外采样和圈养采样，使用不同的实验室技术（麦克马斯特法和微型FLOTAC法）评估是否可以从单个野外样本中估计个体寄生虫感染状态和负荷。我们测试了它们在性能上是否存在差异，并量化了样本处理如何影响寄生虫检测率。我们发现单个野外样本的假阴性率较高。相比之下，在24小时内从圈养环境中采集的样本具有高度可靠性（假阴性少）和准确性（感染强度可重复）。在方法方面，我们发现麦克马斯特技术对虫卵的估计比微型FLOTAC法更具可重复性，两种技术在很大程度上对卵囊同样适用。我们的研究表明，野外样本在准确检测寄生虫的存在方面可能不可靠，尤其是在估计鸣禽体内的寄生虫负荷时。我们强调了对于那些在圈养或野生系统中设计宿主 - 寄生虫研究的人员的重要考虑因素，提供了有助于选择合适方法、最小化偏差并认识到可能局限性的指导意见。
