HOVER-WINTER: a multi-agent model to simulate the overwintering of a beneficial insect (Episyrphus balteatus, Diptera, Syrphidae) in a heterogeneous landscape
Résumé
Understanding how beneficial insects forage in a heterogeneous landscape is of primary importance in conservation biological control. For beneficial insect species that overwinter, survival is linked with the possibility to forage in the landscape for different resources simultaneously. We modelled the behaviour of Episyrphus balteatus (De Geer, 1776), a beneficial species of Syrphidae (Insecta, Diptera) which can overwinter as fertilized adult females and whose larvae feed on aphids occurring on both natural vegetation and crops. The "HOVER-WINTER" multi-agent model focuses on the winter dynamics of an E. balteatus population at the landscape scale. Each individual is modelled as an autonomous agent who behaves according to a set of rules for foraging in the landscape, feeding on flowers, sheltering in forest edges and dying, constrained by climate and land cover. HOVER-WINTER is the first individual based model for E. balteatus. Analysing the trajectories of insects emphasised the role played by meadows and south edges on the overall behaviour of the population. We also studied different scenarios of landscape improvements and showed that landscape configuration had less effect on overwintering success than the temperature and the foraging strategy of the individuals. In any case, landscape improvements greatly enhanced greatly the overwintering success.