Modelling plant-aphid interactions explicitly considering the role of cultural practices : Peach (Prunus persica) - green aphid (Myzus persicae) as study case

Aphids alter plant development and can transmit viruses, thus representing a major threat for crops. Aphid pressure on plant can be reduced and crop production can be enhanced by facilitating some ecological processes in addition, or in substitution, to the use of pesticides. Mathematical models can help in predicting the direction and strength of these ecological processes and they can reveal the impact of alternative ways of managing crops. The proposed thesis aims to develop process based mathematical models coupling plant physiology and aphid demography to drive ecological intensification and reduce the use of pesticides. The models consider i) interactions between plant and aphid, while most crop models only consider the effect of the pest on the plant and not vice versa hence impairing insights upon bottom-up pest control via cultural practices; and ii) the effect of cultural practices and the outcome in terms of harvest, issues that are usually absent in ecological models. Therefore, I firstly couple a mechanistic plant growth model with a pest population model, I calibrate it for a peach-green aphid system and I use it to get insights on the mechanisms behind the response of aphids to fertilization and irrigation. Furthermore, I develop an epidemiological model explicitly accounting for the interference between two aphid vectors. I apply the model to explore the effect of inter-specific aphid interference in shaping the spread of plant viruses, considering the effect of agricultural practices.