Abstract : In the fight against arboviruses transmitted by mosquitoes, several techniques consist in acting directly on the population of mosquitoes. Among these techniques, the Wolbachia technique aims at replacing the population of wild mosquitoes by a population infected by a bacteria named Wolbachia, which is naturally present in many arthropods. Once infected by this bacteria, mosquitoes are not able to transmit viruses like dengue, chikungunya, and zika. Moreover, this bacteria is transmitted from mother to offsprings. Therefore, several experiments are made to study the feasibility of the replacement by locally releasing Wolbachia infected mosquitoes. In this talk, I will present a mathematical study of this replacement strategy. More precisely, we will focus on the spatial spread of the bacteria after some local releases of Wolbachia infected mosquitoes and on the optimal way to perform the releases.