The Impact of Egg Quiescence on the Efficacy of Wolbachia-Infected Mosquito Releases for Arbovirus Control

An ordinary differential model is proposed to understand the role of egg quiescence on the efficacy of releasing Wolbachia-infected mosquitoes to control arbovirus transmission. The model admits up to five equilibrium points and four biologically meaningful scenarios: extinction of both populations; persistence of the uninfected population with extinction of the infected one; persistence of the infected population with extinction of the uninfected one; and coexistence of both populations. This occurs because the coexistence scenario allows for bistability in the system. A sensitivity analysis shows that mosquitoes optimize their fitness by adjusting the quiescence rate. Because Wolbachia-infected eggs do not survive quiescence, or the adults that emerge are infertile, quiescence negatively impacts the fitness of infected mosquitoes, thereby reducing the prevalence of infection in the mosquito population. This increases the chance of encountering an uninfected mosquito, which is more likely to carry the dengue virus compared to a Wolbachia-infected one, potentially increasing the risk of dengue transmission during or after environmental stress that triggers quiescence. More importantly, quiescence can compromise the establishment of infection within the mosquito population by increasing the number of infected mosquitoes required during the release period. Therefore, the use of Wolbachia-infected mosquitoes to control arbovirus transmission in regions where quiescence occurs at a high rate can be jeopardized.