It is acknowledge that economically important crops are more and more damaged by pests and diseases. This is partly due to Climate change but also to international trades that favor the transportation of pests, and diseased seeds or plants. For instance Tephridit fruit flies (which damage fruit and other crops) have already spread du to warmer climate. That is why, Food security has become a major concern in many countries around the world, and in particular in Southern countries. In the past, many field experiments have been done to find a way to avoid or reduce the impact of pests and diseases in crops. These experiments were long, tedious and costly, and, for some, almost impossible to conduct. For a long time adulticides and larvicides were mostly used. We know now that this was a big mistake, having an impact on Human Health and Biodiversity. Biological control tools are needed but since it is impossible to test all scenarios in the field, virtual experiments are more than welcome. Modelling, and in particular Mathematical Modelling, Mathematical Analysis, and Numerical Simulations are some of the best tools to help the experts to select the most important traits to develop resistant crops, as well as the relevant field experiments to conduct in order to improve our knowledge and to test all possible control scenarios.