Effet de la diversité des forêts sur leur résistance aux insectes ravageurs natifs et exotiques (Résumé)

Résumé

In view of the technical, economic and environmental problems raised by curative control of insect pests, greater attention should be paid to developing prevention of entomological risks in forests. An increasing number of meta-analyses and empirical studies suggest that mixed forests suffer less damage from insects than pure forests in a temperate environment. Several mechanisms explain this "associational resistance" (of forest species). The presence of non-host species in mixed forests brings about a decrease in the host tree resource, reduces their accessibility and may alter their traits limiting their colonisation and exploitation by the insect pest. Furthermore, forest species biodiversity leads to an increase in the resource and to habitats that are favourable to the natural enemies of pests and therefore to an improvement in their predatory efficiency. Rather than the wealth of species in a mixed forest, it is more the identity and relative proportions of the various species in the mix that impact their resistance to herbivores. These ecological processes based on the concept of associational resistance could be taken into account to develop alternative silvicultural practices for preserving forest health in the long term.

Abstract

In view of the technical, economic and environmental problems raised by curative control of insect pests, greater attention should be paid to developing prevention of entomological risks in forests. An increasing number of meta-analyses and empirical studies suggest that mixed forests suffer less damage from insects than pure forests in a temperate environment. Several mechanisms explain this "associational resistance" (of forest species). The presence of non-host species in mixed forests brings about a decrease in the host tree resource, reduces their accessibility and may alter their traits limiting their colonisation and exploitation by the insect pest. Furthermore, forest species biodiversity leads to an increase in the resource and to habitats that are favourable to the natural enemies of pests and therefore to an improvement in their predatory efficiency. Rather than the wealth of species in a mixed forest, it is more the identity and relative proportions of the various species in the mix that impact their resistance to herbivores. These ecological processes based on the concept of associational resistance could be taken into account to develop alternative silvicultural practices for preserving forest health in the long term.