Transcriptional regulation of diapause induction in the female Asian tiger mosquito, Aedes albopictus (Skuse)

Photoperiodic diapause refers to developmental arrest in response to a token photoperiodic cue. Precise induction of photoperiodic diapause is essential for the survival of many insects through the winter. However, knowledge of the molecular mechanisms regulating diapause induction is still extremely limited. In Aedes albopictus, short day lengths induce the adult female to produce offspring in which the pharate larva enters diapause inside the chorion of the egg. We have investigated the global transcriptional profiles of diapause induction in Ae. albopictus adult females reared under diapause-inducing (SD) and non-diapause-inducing (LD) photoperiods either without (NB) or with a blood meal (BM). We constructed a comprehensive transcriptome assembly that incorporated previous assemblies from other life-cycle stages. We validated previously described key transcriptional responses to a blood meal. The transcriptional response to SD photoperiods depended on blood meal status (NB vs. BM). The circadian clock genes timeless and cryptochrome 1 were up-regulated under SD conditions in NB females, suggesting a potential role for these genes in photoperiodic time measurement. Oxidative phosphorylation was up-regulated under SD conditions in both NB and BM females, but more so in BM females, suggesting that under SD conditions females up-regulate energy production pathways relative to LD conditions, and this effect is enhanced by blood feeding. Fatty acid synthase was up-regulated under SD conditions in BM females, implying that adult provisioning contributes to the increased lipid content of diapause relative to non-diapause eggs. This study provides candidate genes and pathways for studying diapause induction in other insects.