Circadian rhythms in insect disease vectors

Abstract

Organisms from bacteria to humans have evolved under predictable daily environmental cycles owing to the Earth’s rotation. This strong selection pressure has generated endogenous circadian clocks that regulate many aspects of behaviour, physiology and metabolism, anticipating and synchronising internal time-keeping to changes in the cyclical environment. In haematophagous insect vectors the circadian clock coordinates feeding activity, which is important for the dynamics of pathogen transmission. We have recently witnessed a substantial advance in molecular studies of circadian clocks in insect vector species that has consolidated behavioural data collected over many years, which provided insights into the regulation of the clock in the wild. Next generation sequencing technologies will facilitate the study of vector genomes/transcriptomes both among and within species and illuminate some of the species-specific patterns of adaptive circadian phenotypes that are observed in the field and in the laboratory. In this review we will explore these recent findings and attempt to identify potential areas for further investigation.

Flies as models for circadian clock adaptation to environmental challenges

“…Thus, the adaptation of the daily activity patterns to different environmental conditions can be easily observed in flies, although individual animals are relatively short‐lived and do usually not experience several seasons (only the individuals that overwinter experience autumn, winter, and spring). The great advantage of studying flies is that the molecular and neuronal mechanisms of the circadian clock are well‐understood in D. melanogaster (see King & Sehgal, this issue) and start to emerge also in other Diptera (Bazalova & Dolezel, ; Bertolini et al., ; Codd et al., ; Gentile, Rivas, Meireles‐Filho, Lima, & Peixoto, ; Gesto et al., ; Kaiser et al., ; Kyriacou, ; Meireles‐Filho & Kyriacou, ; Meuti, Stone, Ikeno, & Denlinger, ; Noreen, Pegoraro, Nouroz, Tauber, & Kyriacou, ; Rivas et al., ; Rund, Hou, Ward, Collins, & Duffield, ). In D. melanogaster , recent studies have shown that M and E activity bouts are reflected by Ca 2+ rhythms in the relevant clock neurons controlling M and E activity, respectively (Liang, Holy, & Taghert, , ).…”

Evolution to environmental contamination ablates the circadian clock of an aquatic sentinel species

“…In conjunction with the conservation of core clock genes, our data suggest that D. pulex maintain a molecular clock with similar architecture to those studied in other eukaryotic organisms (Partch, Green, & Takahashi, ; Tilden et al., ). Of note, the expression levels of per and clk in our control population closely resemble the expression of these genes in mosquitoes ( Anopheles gambiae ), relevant as the circadian rhythm of D. pulex is thought to be more like that of butterflies and mosquitos than that of Drosophila (Bernatowicz et al., ; Meireles‐Filho & Kyriacou, ; Rund et al., ; Tilden et al., ).…”

“…Of note, the expression levels of per and clk in our control population closely resemble the expression of these genes in mosquitoes (Anopheles gambiae), relevant as the circadian rhythm of D. pulex is thought to be more like that of butterflies and mosquitos than that of Drosophila (Bernatowicz et al, 2016;Meireles-Filho & Kyriacou, 2013;Rund et al, 2016;Tilden et al, 2011).…”

Mosquito Survey in the Campus Area of Universitas Padjadjaran Jatinangor in September to November 2016

“…activity change due to changes in their circadian rhythms by external factors such as light. 25 The number of Aedes spp. increased in the dormitory at night as students spend time at the dormitory at night, and electrical lighting attracts the mosquito.…”