Effects of nitrogen fertilization and vegetative growth on the population dynamics of the aphid, Myzus persicae, in the peach tree, Prunus persica

The green peach aphid, Myzus persicae, is a major pest in peach orchards. In order to find alternatives to the use of chemicals for aphid control, it is crucial to better understand the interactions between aphid population dynamics and tree status, i.e., growth and nutrient composition of the plant tissues. M. persicae acts as a flush feeder on peach tree. It is assumed that aphid abundance will be maximized on vigorous non-stressed plants, in concordance with the plant vigor hypothesis. How far cultural practices could be used to control plant vigor and, in turn, aphid populations was tested on potted trees submitted to two levels of nitrogen supply (N+ /N-) and artificially infested. We described shoot growth, leaf nitrogen concentration and aphid population levels during the entire infestation period (two months). When separately considering shoot growth and nitrogen treatment, we demonstrated a positive effect of both factors on aphid population dynamics. However, when testing for the concurrent effects of both shoot growth and nitrogen treatment, only shoot growth had a significant positive effect over aphid population dynamics. These results suggest that the observed effect of nitrogen treatment on aphid population dynamics may be indirect, mediated by a modification of plant growth.