Fertility decline in Aedes mosquitoes is associated with reduced maternal transcript deposition and does not depend on female age

Female mosquitoes undergo multiple rounds of reproduction known as gonotrophic cycles. A gonotrophic cycle spans the period from bloodmeal intake to egg laying. Nutrients from vertebrate host blood are necessary for completing egg development. During oogenesis, a female pre-packages mRNA into her oocytes, and these maternal transcripts drive the first two hours of embryonic development prior to zygotic genome activation. In this study, we profiled transcriptional changes in 1-2 hours old Aedes aegypti embryos across two gonotrophic cycles. We found that homeotic genes which are regulators of embryogenesis are downregulated in embryos from the second gonotrophic cycle. Interestingly, embryos produced by Ae. aegypti females progressively reduced their ability to hatch as the number of gonotrophic cycles increased. We show that this fertility decline is due to increased reproductive output and not the mosquitoes age. Moreover, we found a similar decline in fertility and fecundity across three gonotrophic cycles in Ae. albopictus. Our results are useful for predicting mosquito population dynamics to inform vector control efforts.