title: Tree Diversity Limits the Impact of an Invasive Forest Pest.
abstract: The impact of invasive herbivore species may be lower in more diverse plant communities due to mechanisms of associational resistance. According to the "resource concentration hypothesis" the amount and accessibility of host plants is reduced in diverse plant communities, thus limiting the exploitation of resources by consumers. In addition, the "natural enemy hypothesis" suggests that richer plant assemblages provide natural enemies with more complementary resources and habitats, thus promoting top down regulation of herbivores. We tested these two hypotheses by comparing crown damage by the invasive Asian chestnut gall wasp (Dryocosmus kuriphilus) on chestnut trees (Castanea sativa) in pure and mixed stands in Italy. We estimated the defoliation on 70 chestnut trees in 15 mature stands sampled in the same region along a gradient of tree species richness ranging from one species (chestnut monocultures) to four species (mixtures of chestnut and three broadleaved species). Chestnut defoliation was significantly lower in stands with higher tree diversity. Damage on individual chestnut trees decreased with increasing height of neighboring, heterospecific trees. These results suggest that conservation biological control method based on tree species mixtures might help to reduce the impact of the Asian chestnut gall.
authors.affiliation: INRA, DYNAFOR, UMR 1201, 31326 Castanet Tolosan, France; INRA, BIOGECO, UMR 1202, 33610 Cestas, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Guyot
authors.affiliation: Université de Bordeaux, BIOGECO, UMR 1202, 33405 Talence, France; INRA, BIOGECO, UMR 1202, 33610 Cestas, France.
authors.forename: Bastien
authors.initials: B
authors.lastname: Castagneyrol
authors.affiliation: INRA, DYNAFOR, UMR 1201, 31326 Castanet Tolosan, France; Université de Toulouse, INPT-ENSAT, DYNAFOR, UMR 1201, 31326 Castanet Tolosan, France.
authors.forename: Aude
authors.initials: A
authors.lastname: Vialatte
authors.affiliation: INRA, DYNAFOR, UMR 1201, 31326 Castanet Tolosan, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Deconchat
authors.affiliation: Università di Firenze, DISPAA, Laboratori di Botanica, 50144 Florence, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Selvi
authors.affiliation: Università di Firenze, DISPAA, Laboratori di Botanica, 50144 Florence, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Bussotti
authors.affiliation: Université de Bordeaux, BIOGECO, UMR 1202, 33405 Talence, France; INRA, BIOGECO, UMR 1202, 33610 Cestas, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Jactel
mesh_terms: D000818:Animals; D044822:Biodiversity; D065928:Forests; D060434:Herbivory; D007313:Insecta; D058865:Introduced Species; D007558:Italy; D014197:Trees