The Sterile Insect Technique (SIT) is a demographic control procedure consisting in re-leasing males sterilized by ionizing radiations. A workaround technique, named boost-ed SIT, aims at contaminating the sterilized males with pyriproxyfen; the males would then transfer this insecticide to other compartments of the target population (females, breeding sites) through auto-dissemination. To anticipate the effect of SIT and boosted SIT on mosquito populations, they were included into an age-structured population model of Aedes albopictus in the geographical context of La Reunion Island. A sensitiv-ity analysis shows that timing and duration of the male release events, as well as the quantity of sterile males released, are of key importance for both control methods. The persistence of pyriproxyfen in larval habitat appears to be the major determinant for boosted SIT to be more efficient than SIT. While the model appears a powerful tool to investigate release strategies, our findings specifically call for lab experiments towards a better assessment of pyriproxyfen transfer rates and persistence in breeding sites.
The tiger mosquito, Ae. albopictus, is emerging throughout the world as a public health hazard through the transmission of many human pathogens for which no effective antiviral agent or vaccine are available. Chemical insecticides remain the main tools to control the tiger mosquito populations, but the development of resistances is threatening their effectiveness. In this context, it is necessary to develop alternative control methods, one of which is the Sterile Insect Technique (SIT) consisting in releasing males that have been sterilized using ionizing radiation. Those males reduce the reproductive success of the encountered wild females, hence causing the target population to decline. Another method is the boosted SIT, a SIT improvement, where sterile males are also vectors of a biocide transmitted to the females through mating. The biocides (e.g. growth regulators affecting larval development) can be then specifically dispersed to the breeding sites by the females. Yet, experimenting those practices across the relevant space and time scales is costly, as well potentially hazardous. In this context, mathematical models can provide useful tools to test and optimize such control strategies. We will present an age-structured population dynamics model of the vector Ae. albopictus, designed to explore the demographic effects of SIT control strategies. The model accounts for the spatiotemporal heterogeneity of environmental and meteorological conditions across La Reunion Island (Indian Ocean, France). The control strategies and their optimization will be analyzed and discussed.
