Fungi associated with necrotic and asymptomatic galls of Dryocosmus kuriphilus (Hymenoptera: Cynipidae) and the adults of its parasitoid Torymus sinensis in chestnut growing areas of Turkey

Abstract

The chestnut gall wasp (CGW) Dryocosmus kuriphilus is a serious pest of chestnuts (Castanea sativa) in many chestnut growing areas in Turkey. Out of 200 galls randomly collected from four different areas of Yalova and Giresun provinces, 116 showed necrosis, while 84 were asymptomatic. Fungi associated with the necrotic and asymptomatic galls were determined based on morphology and DNA sequencing. Gnomoniopsis smithogilvyi, Colletotrichum acutatum, Penicillium glabrum, Botrysphaeria dothidea, Trichoderma atroviridea, and Botrytis cinerea were found on 49, 11, 10, 8, 7, and 1 necrotic galls, respectively. On the other hand, G. smithogilvyi, Fusarium proliferatum, Aureobasidium sp., C. godetiae, Rhizopus stolonifer, P. glabrum, C. acutatum, Cladosporium sp., Alternaria spp., and Aspergillus sp. were hosted by 37, 35, 15, 14, 12, 8, 6, 3, 1, and 1 asymptomatic galls, respectively. Seven fungi, G. smithogilvyi, C. acutatum, F. proliferatum, B. dothidea, Cryphonectria parasitica, Diplodina castanea, and Penicillium sp. were isolated from 31, 6, 4, 1, 1, 1, and 1 of the dead larvae of D. kuriphilus, respectively. Two fungi, F. proliferatum and Penicillium sp., were isolated from the adults of Torymus sinensis, a parasitoid of CGW. Pathogenicity of G. smithogilvyi, C. acutatum, and F. proliferatum detected from dead larvae of D. kuriphilus and galls was tested on young chestnut saplings: the former two produced necrosis while the third one did not.