Nitrogen and water supplies affect peach tree–green peach aphid interactions: the key role played by vegetative growth

The availabilities of water and nitrogen resources are among the main abiotic factors modifying plant physiology and growth. Consequently, via bottom‐up processes, they also can have an impact on the performance of herbivorous insects. However, the extent to which the modification of plant growth is responsible for such an impact remains unclear. We conducted a factorial experiment quantifying Myzus persicae aphid abundance and the vegetative growth of Prunus persica peach tree shoots under contrasting levels of nitrogen and water supplies. We used a hierarchical analysis of multiple regression models to determine whether the consequences of the availability of nitrogen and water on aphid abundance could be the result of a modification of plant growth. Maximum aphid abundance was achieved under nitrogen and water comfort conditions. The best model explaining variance in aphid abundance took into account vegetative growth and water supply, as well as their interaction. The results of the present study suggest that a higher nitrogen supply increases aphid abundance by fostering plant growth. Additionally, the positive response of aphid abundance to vegetative growth is lower in the case of water restriction because, under such conditions, aphids cannot take full advantage of tree vigour. Such a result provides new insights into aphid control in agriculture, as well as on the possible effects of climate change.