Institute of Tropical Medicine, University of São Paulo, São Paulo, SP, Brazil; São Paulo City Hall, Health Surveillance Unit, São Paulo, SP, Brazil.
Department of Epidemiology, School of Public Health, University of São Paulo, São Paulo, SP, Brazil.
Acta Trop. 2021 Sep;221:106009. doi: 10.1016/j.actatropica.2021.106009. Epub 2021 Jun 12.
São Paulo is one of the largest cities in the world and has several characteristics that favor a diversity of urban and wild mosquitoes. Little is known about how variations in mosquito diversity and feeding preferences for different hosts in different vegetation strata can influence the risk of pathogen transmission to humans. We investigated vertical stratification of mosquitoes and its relationship with vertebrate hosts in environments with different degrees of conservation in two conservation units in the city of São Paulo. Adult mosquitoes were collected using CDC traps, aspiration and Shannon traps. After morphological identification, host blood in engorged females was analyzed by PCR with a vertebrate-specific primer set based on mitochondrial cytochrome b DNA of vertebrates commonly found in the two conservation units. Although a higher abundance of the species Anopheles cruzii and Culex nigripalpus was found in the canopy, blood not only from birds but also from humans and rodents was identified in these mosquitoes. In one of the units, Wyeomyia confusa and Limatus durhamii were found occupying mainly niches at ground level while Culex vaxus was frequently found in the canopy. Haemagogus leucocelaenus, the main vector of yellow fever, was found in low abundance at all collection points, particularly in the canopy. Species richness and composition tended to vary little between canopy and ground level in the same environment, but the abundance between canopy and ground level varied more depending on the species analyzed, the most abundant and frequent species exhibiting a predilection for the canopy. Even those mosquito species observed more frequently in the canopy did not show an association with hosts found in this stratum as most of the blood identified in these species was from humans, suggesting opportunist feeding behavior, i.e., feeding on the most readily available host in the environment. The two most common species in the study, An. cruzii and Cx. nigripalpus, may be able to act as bridge vectors for pathogens to circulate between the forest canopy and ground level.
圣保罗是世界上最大的城市之一，具有多种有利于城市和野生蚊子多样性的特征。对于蚊子多样性的变化以及不同植被层中不同宿主的摄食偏好如何影响病原体向人类传播的风险，人们知之甚少。我们调查了在圣保罗市两个保护单位中具有不同保护程度的环境中蚊子的垂直分层及其与脊椎动物宿主的关系。使用 CDC 诱捕器、抽吸和 Shannon 诱捕器收集成蚊。在形态学鉴定后，用基于在两个保护单位中常见的脊椎动物线粒体细胞色素 b DNA 的脊椎动物特异性引物组对饱血雌蚊中的宿主血液进行 PCR 分析。虽然在树冠中发现了更多的物种 Anopheles cruzii 和 Culex nigripalpus，但在这些蚊子中不仅鉴定出了鸟类的血液，还鉴定出了人类和啮齿动物的血液。在其中一个单位中，Wyeomyia confusa 和 Limatus durhamii 主要占据地面的生态位，而 Culex vaxus 则经常在树冠中发现。黄热病的主要传播媒介 Haemagogus leucocelaenus 在所有采集点的数量都很少，特别是在树冠中。在同一环境中，树冠和地面的物种丰富度和组成变化不大，但由于分析的物种不同，树冠和地面之间的丰度变化更大，最丰富和最频繁的物种表现出对树冠的偏好。即使在树冠中观察到的蚊子物种也与该地层中发现的宿主没有关联，因为在这些物种中鉴定出的大多数血液来自人类，这表明它们具有机会主义的摄食行为，即摄食环境中最容易获得的宿主。在研究中最常见的两种物种 An. cruzii 和 Cx. nigripalpus 可能能够充当病原体在森林树冠和地面之间循环的桥梁媒介。
