A city in the middle of a heatwave rewrites its transit schedule: fewer routes, but each bus runs longer and breaks down less often. The Asian tiger mosquito Aedes albopictus rearranges its own life schedule in much the same way as the temperature around it creeps upward. In the lab, mosquitoes were kept at tropical heat for three years, 32°C by day and 26°C by night, and every five generations the researchers checked how their bodies and habits were changing.
In the first generation, the heat acted as a stressor: the mosquitoes lived shorter lives but rushed to leave offspring, developing faster and laying more eggs. By generations 10-15, the picture had flipped. Females lived as long as their relatives in cooler conditions, yet laid fewer eggs. This is not a temporary adjustment but a new balance locked into heredity. Males adapted more slowly than females, and that is a worrying sign: they are more vulnerable to heat.
Scientists looked inside the fat body of newborn females, the organ where an insect stores energy. Gene activity there had shifted: instead of responding to stress, the cells took up fat storage. When some of the "tropical" lines were returned to cooler conditions, half of the genes reverted to their previous state, but 250 genes kept the changes. That means adaptation to heat is written into heredity, not simply switched on for a while.
The biggest contribution to overall success came not from fecundity or longevity but from survival from egg to adult. That is what determines how many females live long enough to bite for the first time. For cities where mosquitoes transmit dengue and Zika, this means disease-spread models must account not only for the weather but also for the speed of insect evolution.
A city that has learned to live in the heat does not become safer. It simply distributes its resources differently. Mosquitoes are doing the same thing, and that changes the rules of the game for everyone trying to control them.
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.