Aedes mosquitoes transmit dengue, Zika and chikungunya, threatening half of humanity. As small cold-blooded creatures, they respond sharply to ambient temperature. Alongside this work, the archive holds studies of climate signals, urban dengue fever and temperature rhythms in the Po Valley, but all of them describe reactions to weather, not evolution. Until now, scientists debated whether mosquitoes could genetically adapt to warming over decades or merely adjust plastically to heat. Experimental evolution over 20 generations has finally answered that question.
The researchers created ten lines of Aedes albopictus: five lived under a tropical regime (32°C by day, 26°C at night), five under a standard one (28°C by day, 26°C at night). After 13 generations, some of the tropical lines were returned to cooler conditions to separate inherited changes from temporary acclimation. Every five generations they measured survival, development rate, fecundity, wing size, energy reserves, behavioral responses to heat and the freezing point of eggs. They also sequenced RNA from the fat body of newly emerged females at generations 1 and 15 and after the selection was lifted.
In the first generation under heat, the mosquitoes lived shorter lives but developed faster and produced more offspring. By generation 10–15, the picture had flipped: female lifespan rose to control levels, while fecundity fell and then stabilized. This is a locked-in trade-off between reproduction and survival. Males adapted more slowly than females, which points to their greater vulnerability to heat. The fat body transcriptome shifted from a stress response to enhanced biosynthesis and lipid accumulation. When selection was lifted, half of the genes returned to their original expression levels, but 250 genes kept their altered state, indicating inherited adaptation. The model showed that the main contributor to overall reproductive success is survival from egg to adult, not fecundity or longevity.
What sets this work apart from neighboring climate studies is that it tracked mosquito evolution under controlled conditions for 20 generations for the first time. This is not a correlation along latitudinal gradients but a direct experiment with replicates and removal of selection. The result changes our view of how fast invasive species can adapt: mosquitoes may evolve over a few years, not decades. For modeling the risk of arboviral infections, this means we must account not only for plasticity but also for rapid evolutionary shifts.
The field could move toward identifying the specific genes responsible for thermal adaptation. The 250 'sustained' genes and the set of thermosensitive traits provide targets for genetic testing. Epigenetic mechanisms and the role of the microbiome in adaptation could also be explored. Comparing with other mosquito species, such as Aedes aegypti, will show how universal the discovered trade-off is.
The results will influence epidemiological modeling of dengue and Zika spread under climate warming. They are also important for mosquito control programs, especially those using sterile males or Wolbachia.
The next step is whole-genome sequencing of lines at different generations to identify alleles under selection. Then we can test whether epigenetic marks accelerate adaptation and compare with wild populations from the tropics.
This work directly addresses an unsolved problem in ecology: how quickly cold-blooded animals can evolutionarily keep pace with climate change. For medical entomology, it raises the question of whether mosquitoes will become more dangerous vectors in a warming world.
The tropical mosquito lines produced only six generations per year instead of eight in the controls, even though up to thirteen are predicted in real tropics. This shows that laboratory heat does not fully mimic nature.
In Frank Herbert's novel Dune, the sandworms of Arrakis are adapted to extreme heat and dryness. This work shows that even ordinary mosquitoes can evolve quickly under a new climate, though not in a single generation.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.