Center for Infectious Disease Dynamics & Department of Entomology, The Pennsylvania State University, University Park, PA, 16802, USA.
School of Life Sciences, Monash University, Clayton, Vic, 3800, Australia.
Heredity (Edinb). 2022 Oct;129(4):215-224. doi: 10.1038/s41437-022-00553-x. Epub 2022 Jul 22.
Wolbachia is an insect endosymbiont being used for biological control in the mosquito Aedes aegypti because it causes cytoplasmic incompatibility (CI) and limits viral replication of dengue, chikungunya, and Zika viruses. While the genetic mechanism of pathogen blocking (PB) is not fully understood, the strength of both CI and PB are positively correlated with Wolbachia densities in the host. Wolbachia densities are determined by a combination of Wolbachia strain and insect genotype, as well as interactions with the environment. We employed both artificial selection and inbreeding with the goal of creating lines of Ae. aegypti with heritable and distinct Wolbachia densities so that we might better dissect the mechanism underlying PB. We were unable to shift the mean relative Wolbachia density in Ae. aegypti lines by either strategy, with relative densities instead tending to cycle over a narrow range. In lieu of this, we used Wolbachia densities in mosquito legs as predictors of relative densities in the remaining individual's carcass. Because we worked with outbred mosquitoes, our findings indicate either a lack of genetic variation in the mosquito for controlling relative density, natural selection against extreme densities, or a predominance of environmental factors affecting densities. Our study reveals that there are moderating forces acting on relative Wolbachia densities that may help to stabilize density phenotypes post field release. We also show a means to accurately bin vector carcasses into high and low categories for non-DNA omics-based studies of Wolbachia-mediated traits.
沃尔巴克氏体是一种昆虫共生体，正被用于控制埃及伊蚊，因为它会导致细胞质不亲和（CI）并限制登革热、基孔肯雅热和寨卡病毒的复制。虽然病原体阻断（PB）的遗传机制尚未完全理解，但 CI 和 PB 的强度均与宿主中的沃尔巴克氏体密度呈正相关。沃尔巴克氏体密度由沃尔巴克氏体菌株和昆虫基因型的组合以及与环境的相互作用决定。我们采用了人工选择和近亲繁殖的方法，目的是创建具有可遗传和不同沃尔巴克氏体密度的埃及伊蚊系，以便更好地剖析 PB 的机制。我们无法通过这两种策略改变埃及伊蚊系中的平均相对沃尔巴克氏体密度，而是相对密度往往在一个狭窄的范围内波动。因此，我们使用蚊子腿部的沃尔巴克氏体密度作为预测剩余个体尸体中相对密度的指标。由于我们使用的是杂交蚊子，我们的研究结果表明，控制相对密度的蚊子中缺乏遗传变异，或者对极端密度的自然选择，或者是影响密度的环境因素占主导地位。我们的研究表明，有一些调节力量作用于相对沃尔巴克氏体密度，这可能有助于稳定田间释放后的密度表型。我们还展示了一种将载体尸体准确分类为高和低类别的方法，用于基于非 DNA 组学的沃尔巴克氏介导性状的研究。
