Warmer Temperature Accelerates the Aging-Dependent Decrease in Female Ovary Size, Delays Male Accessory Gland Development, and Accelerates Aging-Dependent Changes in Reproductive Gene Expression in Anopheles gambiae Mosquitoes

In most mosquito species, reproduction requires mating between the female and the male, followed by the female blood-feeding, completing oogenesis, and laying eggs. Warmer environmental temperature and aging both reduce mosquito fecundity and fertility, and warmer temperature accelerates the aging-dependent decline in reproduction such that reproductive impairment manifests earlier in life. To shed light on how this warming-based acceleration of reproductive senescence occurs, we investigated how temperature (27 °C, 30 °C, and 32 °C) and aging interactively shape female and male reproductive tissue size in the African malaria mosquito, <i>Anopheles gambiae</i>. In blood-fed females, we discovered that warmer temperature accelerates the aging-dependent decrease in the size of the ovaries but not the spermatheca. In males, we discovered that warmer temperature lessens and delays the aging-dependent increase in the size of the male accessory glands but not the testes. Next, we measured the expression of reproductive genes in females and males. In female reproductive tissues, warmer temperature accelerates the aging-dependent decrease in the expression of vitellogenin and the aging-dependent increase in the expression of <i>MISO</i> and <i>HPX15</i>. In male reproductive tissues, warmer temperature accelerates an aging-dependent decrease in the expression of <i>Plugin</i>, <i>TGase3</i>, <i>phLP</i>, and <i>CYP315A1</i>. Altogether, these data shed light on how physical and transcriptional changes underpin the warming-based acceleration of an aging-dependent decline in mosquito fecundity and fertility.