Newly invaded territories by Dryocosmus kuriphilus in Spain and first records of Torymus sinensis in the Sistema Central

Abstract

Aim of the study: To update the distribution of Dryocosmus kuriphilus, the Asian chestnut gall wasp, focusing on the central area of the country (Sistema Central). Gall samplings of these areas were carried to obtain the first records of parasitoids on D. kuriphilus in this area. Area of study: Spain and, especially, the Sistema Central. Materials and methods: Georeferenced new records were used to produce a map with the updated distribution of D. kuriphilus as of 2019. Galls were collected and stored in emergence boxes. Parasitoids that emerge from these galls were collected and identified at the most detailed taxonomic level. Main results: The alien species D. kuriphilus was found in the Spanish Sistema Central. Infestation focal points were detected in the Valle del Jerte (South of Sierra de Gredos), Sierra de Francia and in the mountains southwest of Madrid. In all detected focal points of infestation, the available evidence indicates that introduction was caused by the accidental mobilization of infested chestnut material. Alongside other parasitoids recruited by D. kuriphilus, we found individuals of Torymus sinensis, constituting the first records of this foreign species in the Sistema Central. Research highlights: We updated the previously published distribution of D. kuriphilus in Spain, an alien species and pest of chestnut forests and orchards. We also reported the first list of recruited parasitoids by D. kuriphilus and, more specifically, the first records of T. sinensis in the Sistema Central. Keywords: Asian chestnut gall wasp; Torymus sinensis; parasitoids; galls; Iberian Peninsula; pest species; alien species.