Ecophysiological responses and vulnerability to other pathologies in European chestnut coppices, heavily infested by the Asian chestnut gall wasp

•Invasive Asian chestnut gall wasp (ACGW) colonizes massively Italian chestnut woods.•ACGW affected the vigour of sprouts in coppices by reducing leaf surface.•Gall-infested leaves showed a reduction in CO2 assimilation and stomatal conductance.•Chestnut blight appears not yet affected by ACGW, Gnomoniopsis sp. spread increased.•ACGW spread opens unpredictable scenarios for the maintenance of chestnut stands.