García-Del Río Marina, Castaño-Vázquez Francisco, Martínez Javier, Martínez-de la Puente Josué, Cantarero Alejandro, García-Velasco Javier, Merino Yago, Merino Santiago
Department of Evolutionary Ecology, National Museum of Natural Sciences, Spanish National Research Council (CSIC), Madrid, Spain.
Department of Biodiversity, Ecology and Evolution, Complutense University of Madrid, Madrid, Spain.
Mol Ecol. 2024 Oct;33(19):e17517. doi: 10.1111/mec.17517. Epub 2024 Aug 28.
Sexual differences in pathogen prevalence in wildlife often arise from varying susceptibility influenced by factors such as sex hormones and exposure to pathogens. In the case of vector-borne pathogens, host selection by insect vectors determines the exposure of hosts to infections, largely affecting the transmission of these infectious diseases. We identify the blood-feeding patterns of insect vectors in Blue Tit (Cyanistes caeruleus) nestlings in a 3-year study. Blood from both nestlings and insect vectors (Culicoides spp. and Simuliidae) captured inside nest-boxes were used to molecularly determine the sex of the host. We then compared the sex-ratios of the nestlings that had been bitten and those of the complete brood in each nest. We found that males were bitten more frequently than females in 2021, when males weighed less in comparison to other years. Additionally, we molecularly identified bitten nestlings individually by genotyping the DNA of blood obtained from both, the vector's abdomen and nestlings of each brood in 2022. Nestlings more frequently bitten by vectors were males, weighed less and were closest to the nest entrance. To our knowledge this is the first study identifying the nestling selection by insect vectors in bird nests under natural conditions. These results contribute to understanding the mechanisms of host selection by insect vectors, shedding light on pathogen transmission and offering insights into the observed sex-biased infections in wildlife populations.
野生动物中病原体流行率的性别差异通常源于受性激素和病原体暴露等因素影响的易感性差异。对于媒介传播的病原体而言，昆虫媒介对宿主的选择决定了宿主接触感染的情况，在很大程度上影响了这些传染病的传播。在一项为期3年的研究中，我们确定了蓝山雀（Cyanistes caeruleus）雏鸟体内昆虫媒介的吸血模式。从巢箱内捕获的雏鸟和昆虫媒介（库蠓属和蚋科）的血液被用于从分子层面确定宿主的性别。然后，我们比较了被叮咬雏鸟的性别比例与每个巢穴中整个雏鸟群体的性别比例。我们发现，在2021年，雄性比雌性更频繁地被叮咬，当时雄性体重比其他年份轻。此外，在2022年，我们通过对从每个巢中昆虫媒介腹部和雏鸟获得的血液DNA进行基因分型，分别从分子层面鉴定被叮咬的雏鸟。更频繁被媒介叮咬的雏鸟是雄性，体重较轻，且离巢口最近。据我们所知，这是第一项在自然条件下确定鸟巢中昆虫媒介对雏鸟选择的研究。这些结果有助于理解昆虫媒介选择宿主的机制，揭示病原体传播情况，并为野生动物种群中观察到的性别偏向性感染提供见解。
