The consequences of aphid infestation on fruit production become evident in a multi-year perspective: Insights from a virtual experiment

Aphids are commonly considered major agricultural pests because of their ability to severely alter host plant physiology. However, their effects on fruit tree yield have not received wide attention and few existing works considering plant-aphid interaction and its consequences have only been conducted over a single year. We modified an existing process based model for the peach tree Prunus persica − green aphid Myzus persicae pathosystem, explicitly considering interactions between the two species under the influence of cultural practices (i.e. winter pruning and nitrogen fertilization), in order to simulate multi-year dynamics. The new model indicates that fertilization affects plant growth more than aphid infestation and the consequences of aphid infestation over fruit yield only emerge when considering the entire tree life span (ca. 10 yr). In fact, in a given year, aphid infestation mainly impairs shoot growth and, as fruits are borne on 1-yr old wood, its effects on fruit production are delayed in time. Our results are in accordance with the few existing experimental studies and highlight the need of considering multi-year dynamics, both via modelling and field observations, when dealing with perennial crops as fruit trees.