A schematic illustration of how the dependence of individual fitness (A) upon total population size or density [] (B) could hypothetically cause mosquito populations to collapse without the opportunity for resistance to emerge (C) following rapid deployment of insecticidal vector control measures at high but imperfect levels of biological coverage. All outcomes plotted along the Y axis represent relative values for a given intervention scenario (Ω), with a given level of protective coverage of all available blood, sugar or aquatic resources (CA,p), compared to a baseline scenario (Ω = 0). A: Individual fitness is expressed as the reproductive number (R; the average number of female adult offspring per healthy female adult mosquito). B: Population size is expressed as the adult emergence rate (E). C: The rate at which the frequency physiological insecticide resistance traits increase to fixation or equilibrium.