Centre for Ecology and Conservation, University of Exeter Cornwall campus, Treliever Road, Penryn, TR10 9FE, United Kingdom.
Laboratory of Entomology, Droevendaalsesteeg 1, Wageningen University and Research, 6708 PB Wageningen, The Netherlands.
J Appl Microbiol. 2024 Nov 4;135(11). doi: 10.1093/jambio/lxae261.
A wide range of vector control programmes rely on the efficient production and release of male mosquito. Asaia bacteria are described as potential symbionts of several mosquito species but their relationship with Aedes aegypti has never been rigorously tested. Here, we aimed to quantify the benefits of three Asaia species on host development in Ae. aegypti, and the ability of these bacteria to form a stable symbiotic association with growing larvae.
In order to disentangle direct and indirect effects of Asaia inoculation on host development, experiments used insects with an intact microbiome and those reared in near-aseptic conditions, while we characterized bacterial communities and Asaia densities with culture dependent and independent methods (16S rRNA amplicon sequencing). Neonate larvae were inoculated with Asaia spp. for 24 h, or left as uninoculated controls, all were reared on sterile food. Aseptic larvae were produced by surface sterilization of eggs. Although all Asaia were transient members of the gut community, two species accelerated larval development relative to controls. The two mutualistic species had lasting impacts on the larval microbiome, largely by altering the relative abundance of dominant bacteria, namely Klebsiella and Pseudomonas. Axenic larvae were dominated by Asaia when inoculated with this species but showed slower development than conventionally reared insects, indicating that Asaia alone could not restore normal development.
Our results reveal Asaia as a poor mutualist for Ae. aegypti, but with a species-specific positive effect on improving host performance mediated by interactions with other bacteria.
许多蚊虫控制项目依赖于高效生产和释放雄性蚊虫。Asaia 细菌被描述为几种蚊子的潜在共生体，但它们与埃及伊蚊的关系从未经过严格测试。在这里，我们旨在量化三种 Asaia 物种对埃及伊蚊宿主发育的益处，以及这些细菌与生长中的幼虫形成稳定共生关系的能力。
为了理清 Asaia 接种对宿主发育的直接和间接影响，实验使用了具有完整微生物组的昆虫和在近无菌条件下饲养的昆虫，同时我们使用依赖培养和独立方法（16S rRNA 扩增子测序）来描述细菌群落和 Asaia 密度。将新生幼虫用 Asaia spp. 接种 24 小时，或作为未接种对照留作空白，所有幼虫均在无菌食物上饲养。无菌幼虫是通过卵的表面消毒产生的。尽管所有 Asaia 都是肠道群落的短暂成员，但有两种物种相对于对照加速了幼虫的发育。这两种共生物种对幼虫微生物群产生了持久的影响，主要是通过改变优势细菌（即克雷伯氏菌和假单胞菌）的相对丰度。当用该物种接种无菌幼虫时，它们被 Asaia 主导，但发育速度比常规饲养的昆虫慢，表明 Asaia 本身不能恢复正常发育。
我们的结果表明，Asaia 是埃及伊蚊的一种较差的共生体，但通过与其他细菌的相互作用，对改善宿主性能具有特定的积极影响。
