Wolbachia densities in the mosquito Aedes aegypti
Open Access
- Author:
- Mejia, Austin
- Graduate Program:
- Entomology
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 06, 2022
- Committee Members:
- Gary Felton, Program Head/Chair
Elizabeth Ann Mcgraw, Thesis Advisor/Co-Advisor
Jason Laurence Rasgon, Committee Member
Todd C Lajeunesse, Committee Member - Keywords:
- Wolbachia
density
Aedes aegypti
mosquito
symbiont
Wolbachia
density
Aedes aegypti
mosquito
symbiont
artificial selection
inbreeding
biocontrol - Abstract:
- The mosquito Aedes aegypti is a vector for viruses like dengue, chikungunya, and Zika. These arboviruses in most cases cause low mortality in humans but can lead to long-term complications. Dengue virus can also lead to severe forms resulting in death. Currently, there are no effective vaccines or drugs to combat these arboviruses. By 2050, it is expected that ~50% of the world will live in association with Aedes species vectors due to climate change and increasing urbanization. One critical tool to control arbovirus transmission in Ae. aegypti is the vertically inherited insect endosymbiont, Wolbachia. Ae. aegypti is not naturally infected with Wolbachia, but stably infected lines have been created by transinfection. Wolbachia causes two main traits of interest in mosquitoes; Cytoplasmic Incompatibility (CI) and viral blocking. CI manifests as embryonic death resulting from the mating of a Wolbachia infected male with an uninfected female. Wolbachia-infected females do not suffer any such issue and so the symbiont tends to spread through populations. CI Wolbachia-infected males have been released into wild populations to crash native mosquito populations. Viral blocking is where Wolbachia limits the replication of dengue, chikungunya, and Zika viruses in the vector. Together with CI, this effect has led to the release of Wolbachia-infected females to replace native mosquito populations that then exhibit reduced virus transmission. In chapter 1, I reviewed both control strategies, how Wolbachia’s density affects CI and viral blocking strength, and the factors that affect Wolbachia density in insects. In chapter 2, I examined the relative densities of Wolbachia in somatic and reproductive tissues of Ae. aegypti and assessed whether densities are correlated across tissues in the same individual and across generations. In chapter 3, I attempted to create Ae. aegypti with stable low and high Wolbachia densities using artificial selection and inbreeding so that we could better study the basis of Wolbachia-mediated traits. Additionally, I assessed whether Wolbachia densities in mosquito legs could be used as sentinels for predicting densities in the remainder of the insect body as a non-destructive means for accurately binning mosquitoes into high and low-density groups. Finally, in chapter 4, I discuss key findings in chapters 2 and 3, what they mean in our understanding of Wolbachia:insect associations, and what our results mean for field releases of Wolbachia-infected mosquitoes for biocontrol.