Fertility decline in Aedes aegypti 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 blood meal
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 before zygotic genome activation. In this
study, we profiled transcriptional changes in 1-2 hour-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.