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. 2013 Dec 20;8(12):e81860. doi: 10.1371/journal.pone.0081860

Figure 7. The effect of immigration on the frequency of adult females carrying an anti-pathogen gene two years after releases end under a point-source release of adult male transgenic mosquitoes with weekly releases of (A) 80 males released per site, with the anti-pathogen gene carrying a fitness cost, (B) 80 males released per site, with no fitness cost, (C) 160 males released per site, with the anti-pathogen gene carrying a fitness cost, and (D) 160 males released per site, with no fitness cost.

Figure 7

These release numbers represent values that resulted in relatively low (80 males per site each week) and high (160 males released per site each week) levels of variability across replicate simulations in the frequencies of the anti-pathogen gene (Fig. 5A). We focused our analysis of the effects of immigration on release numbers where population extinction never occurred. These release numbers correspond to total release numbers of approximately 1 million (A–B) to 2 million (C–D) transgenic adult males over a single year. Only gravid wild-type females are assumed to migrate into the system. Although removing the fitness cost can reduce the impact of immigration, increasing the number of mosquitoes released amplifies the ability of immigration to counteract the replacement strategy. With immigration, none of the model runs result in extinction across the simulated region. As in figures 46, each model run represents a different, randomized spatial configuration of sites.