Temperature modulates the dissemination potential ofMicrosporidia MB,a malaria-blocking endosymbiont ofAnophelesmosquitoes

Abstract

The endosymbiontMicrosporidia MBis a promising malaria control strategy that inhibits the development ofPlasmodiumnaturally inAnophelesmosquitoes. To be successful, it would be necessary to significantly increase the prevalence ofMicrosporidia MBin populations of malaria mosquitoes to decrease the malaria transmission potential of the mosquito population. However, very little is known about the role of temperature in driving the prevalence ofMicrosporidia MBinfections in mosquito populations. By rearing mosquito larvae under four air temperature regimes (22°C, 27°C, 32°C and 37°C), we show that warm temperatures favour the growth ofMicrosporidia MBinfected larvae. In addition,Microsporidia MBinfected larvae developed faster compared to the uninfected offspring of the same mothers. Starting with 10Microsporidia MBinfected mothers, our population growth model showed that, at 32°C, it would take 15-35 days to reach a population of 1000Microsporidia MBinfected mothers; this represents a dissemination potential of 4.7, 1.3 and 1.7 times higher compared to 22°C, 27°C and 37°C, respectively. Despite a relatively high mosquito mortality rate (20% more compared to 27°C), 32°C was estimated the best temperature for rearingMicrosporidia MBinfected larvae due to the shorter development time and high infection rate. This study gives insight into the favourable conditions forMicrosporidia MBmass rearing and potential release strategies in malarious regions.