Estación Experimental de Zonas Áridas (EEZA-CSIC), Ctra. de Sacramento s/n, La Cañada de San Urbano, 04120, Almería, Spain.
Parasitol Res. 2012 May;110(5):1733-9. doi: 10.1007/s00436-011-2693-9. Epub 2011 Oct 21.
The dynamics of host-parasite interactions depends to a large extent on the effect of host responses on parasite fitness. An increased research effort is currently being invested in the study of host influence on parasite fitness both at a population and at an individual level even though basic information (e.g. the reproductive anatomy of parasites) is frequently missing. Here, we study for the first time the reproductive system of the diptera Carnus hemapterus, a 2-mm long, highly mobile haematophagous fly parasitizing nestlings of a broad variety of bird species. Although this species is poorly known, it is being increasingly used for the study of host-parasite interactions. We also assess the reliability of a method to estimate fecundity based on the number of laid eggs per gravid female and analyse the effect of body size on fecundity estimates. Our results show that carnid flies are synovigenic, so that both the number of laid eggs at a given moment and the egg load represent only a fraction of the true potential fecundity. Moreover, laid eggs are probably a fraction of the number of mature eggs ready to be laid since females withheld seemingly mature eggs at oviposition. A high proportion of pregnant females did not lay eggs, and the number of eggs laid per pregnant female varied remarkably. The latter is explained partly by a positive relationship with body size (thorax length and abdomen width). Caution is needed when using the number of laid eggs as a shortcut estimation of fecundity in C. hemapterus. We propose some improvements to the method for assessing Carnus fertility.
宿主-寄生虫相互作用的动态在很大程度上取决于宿主反应对寄生虫适应性的影响。目前，人们正在投入大量的研究努力来研究宿主对寄生虫适应性的影响，包括在种群和个体水平上的影响，尽管基本信息（例如寄生虫的生殖解剖结构）经常缺失。在这里，我们首次研究了双翅目 Carnus hemapterus 的生殖系统，这是一种 2 毫米长的、高度活跃的血食性蝇，寄生在多种鸟类雏鸟身上。尽管这种物种知之甚少，但它越来越多地被用于研究宿主-寄生虫相互作用。我们还评估了一种基于每只怀孕雌虫产卵数来估计生殖力的方法的可靠性，并分析了体型对生殖力估计的影响。我们的结果表明，肉食蝇是同步生殖的，因此在给定时刻产卵的数量和卵负荷仅代表真实潜在生殖力的一部分。此外，产下的卵可能只是即将产下的成熟卵数量的一部分，因为雌虫在产卵时会保留看似成熟的卵。相当多的怀孕雌虫没有产卵，而且每只怀孕雌虫产卵的数量差异很大。这种情况部分可以通过与体型（胸部长度和腹部宽度）呈正相关来解释。在使用产下的卵数作为肉食蝇生殖力的捷径估计时需要谨慎。我们提出了一些改进评估 Carnus 生殖力方法的建议。
