Biological Invasions (2018) 20, 1459-1473

Pilar Fernandez-Conradi, Nicolas Borowiec, Xavier Capdevielle, Bastien Castagneyrol, Alberto Maltoni, Cécile Robin, Federico Selvi, Inge Van Halder, Fabrice Vétillard and Hervé Jactel (2018)
Plant neighbour identity and invasive pathogen infection affect associational resistance to an invasive gall wasp
Biological Invasions 20 (6), 1459-1473
Abstract: Theory predicts that mixed forests are more resistant to native pests than pure forests (i.e. associational resistance) because of reduced host accessibility and increased top-down control by natural enemies. Yet, whether the same mechanisms also apply to invasive pests remains to be verified. We tested the hypothesis of associational resistance against the invasive Asian chestnut gall wasp (ACGW, Dryocosmus kuriphilus) by comparing ACGW infestation rates on chestnuts (Castanea sativa) in stands varying in species composition (chestnut alone or associated with oaks, pines or ashes). We investigated the effects of reduced chestnut density and frequency in mixed stands, as well as the effect of biotic interactions between ACGW, its parasitoids and the chestnut blight disease (caused by Cryphonectria parasitica). ACGW infestation rates were significantly lower in chestnut–oak and chestnut–ash mixtures than in pure chestnut stands and chestnut–pine mixtures. Infestation rate decreased with decreasing chestnut relative proportion. The composition of native parasitoid communities emerged from galls significantly differed between pure and mixed chestnut stands, but not the species richness or abundance of parasitoids. The abundance of the introduced parasitoid Torymus sinensis was not correlated with ACGW infestation rates and was independent of stand composition. Blight symptoms modified ACGW infestation rates with taller trees being preferred when they were asymptomatic but avoided when they presented blight disease damage. Our results suggest that conservation biological control based on tree species mixtures could contribute to reducing the damage of invasive forest pests.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Hervé Jactel

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Cryphonectria parasitica	Chestnut (Castanea)
	Dryocosmus kuriphilus	Chestnut (Castanea)
Torymus sinensis (parasitoid)	Dryocosmus kuriphilus