Circadian rhythm of mosquitoes: Blood feeding and disease transmission

Abstract

The circadian rhythm refers to the adjustment of behavioural rhythms of organisms' to the environmental cues. The rhythm adjusting and maintaining is done through an internal timekeeping mechanism. The timekeeping mechanism is governed through a series of translational transcription feedback loops that obtain the environmental cues from outside and translate them to behavioural rhythms through a series of neurotransmitters and gene transcriptions. The behavioural rhythms are essential for the animals to stay in optimal conditions. The circadian rhythm is especially important for blood-feeding arthropods, such as mosquitoes, to adjust their feeding times to the optimal time window of the day. The time window depends on host availability, evasion of predators, and other factors like humidity and temperature. This process ensures the optimum feeding and maximum efficiency in the parasite transmission. This mechanism plays an important role in the mosquito-borne disease transmission. Furthermore, due to the blood meal-induced processes such as trypsin activation and vitellogenesis, the time of blood meal might affect the mosquito's survival and reproductive health. The circadian timekeeping mechanism depends on external environmental cues. The changing of the environmental conditions due to climatic change and human intervention may alter the circadian behavioural rhythms and make erratic behaviours that are hard to predict and, in turn preventing the spread of mosquito-borne diseases. In here, we look into the circadian patterns in blood feeding in mosquitoes, the impact of environmental factors, the genetic control, and how it might contribute to the disease transmission.