Amat-Valero M, Calero-Torralbo M A, Valera F
Departamento de Ecología Funcional y Evolutiva, Estación Experimental de Zonas Áridas EEZA-CSIC, Ctra. Sacramento s/n, La Cañada de San Urbano, 04120 Almería, Spain.
Parasitology. 2013 Sep;140(11):1357-67. doi: 10.1017/S0031182013000929. Epub 2013 Jul 22.
Understanding the population dynamics and co-evolution of host–parasite systems requires detailed knowledge of their phenology which, in turn, requires a deep knowledge of the effect of abiotic factors on the life cycles of organisms. Temperature is known to be a key environmental influence that participates in the regulation of diapause. Yet, not much is known about the effect of temperature on the free-living stages of true parasites and how it may influence host–parasite interactions. Here we experimentally study the effect of ambient temperature on overwintering pupae of Carnus hemapterus (Diptera, Carnidae), an ectoparasitic fly of various bird species. We also test whether chilling is a prerequisite for completion of diapause in this species. In the course of three winter seasons we experimentally exposed carnid pupae from nests of various host species to spring temperatures with and without chilling and recorded the emergence patterns in experimental and control groups. Experimental groups showed an advanced emergence date, a lower emergence rate and, consequently, a protracted emergence period. Chilling had no obvious effect on the start of emergence but it did advance the mean emergence date, shortened the length of the emergence period when compared with the control treatment and increased the emergence rate when compared with the spring treatment. This study identifies an environmental cue, namely temperature during the free-living stage, affecting the emergence of a widespread parasite and demonstrates the plasticity of diapause in this parasite. Our findings are of potential significance in understanding host–parasite interactions.
了解宿主 - 寄生虫系统的种群动态和共同进化需要详细掌握它们的物候学，而这又需要深入了解非生物因素对生物体生命周期的影响。已知温度是参与滞育调节的关键环境影响因素。然而，关于温度对真正寄生虫自由生活阶段的影响以及它如何影响宿主 - 寄生虫相互作用，我们所知甚少。在这里，我们通过实验研究环境温度对肉蝇（双翅目，肉蝇科）越冬蛹的影响，肉蝇是多种鸟类的体外寄生蝇。我们还测试了低温是否是该物种完成滞育的先决条件。在三个冬季期间，我们将来自不同宿主物种巢穴的肉蝇蛹在有低温和无低温的情况下暴露于春季温度，并记录实验组和对照组的羽化模式。实验组显示羽化日期提前、羽化率较低，因此羽化期延长。低温对羽化开始没有明显影响，但与对照处理相比，它确实提前了平均羽化日期，缩短了羽化期的长度，并且与春季处理相比提高了羽化率。本研究确定了一种环境线索，即自由生活阶段的温度，影响一种广泛存在的寄生虫的羽化，并证明了这种寄生虫滞育的可塑性。我们的研究结果对于理解宿主 - 寄生虫相互作用具有潜在意义。
