Professor Vanderbilt University Nashville, Tennessee
As a poikilothermic ectotherm, a mosquito’s body temperature varies with that of its environment. Body temperature dictates the efficacy of many physiological processes, so shifts in environmental temperature influence how mosquitoes develop, respond to infection, and transmit disease. Moreover, as a mosquito ages, its body condition deteriorates and the immune system weakens, a process known as senescence. Thus, individually, both temperature and age impact the strength of the immune response, but whether temperature influences the progression of senescence is unknown. We began to investigate this by scrutinizing the interplay of temperature and age on adult female Anopheles gambiae survivorship and infection intensity. Mosquitoes were reared under three constant temperatures of 27℃, 30℃, or 32℃ and were exposed to an immune treatment at either 1-, 5-, 10-, or 15-days post eclosion. In experiments measuring adult lifespan, we found that as the temperature increased, average adult lifespan decreased. An infection with E. coli further decreased survival for all ages and temperatures tested. An M. luteus infection decreased survival for all ages at 32℃, but at cooler temperatures, survival only decreased when mosquitoes were infected at 15-days post eclosion. In experiments measuring infection intensity, we found that with older age, the intensity of infection increased, and that this increase occurred at an earlier age in warmer temperatures. Combined, these results suggest that the progression of senescence is accelerated in warmer temperatures.