Ophiostomatales (Ascomycota) associated with Tomicus species in southwestern China with an emphasis on Ophiostoma canum

Abstract

Ophiostomatalean fungi may facilitate bark beetle colonization and reproduction. In the present study of the fungal community associated with bark beetle species belonging to Tomicus in Yunnan, China, six ophiostomatalean fungi (Ophiostoma canum, O. ips, O. tingens, Leptographium yunnanense, Leptographium sp. 1 and Leptographium sp. 2) were isolated from the beetles or their galleries; O. canum was the most common fungal species. The distribution of O. canum was associated with stands heavily damaged by Tomicus species and a higher percentage of valid galleries of Tomicus yunnanensis and T. minor in Yunnan pine (Pinus yunnanensis). After inoculation of Yunnan pine with the fungus, a phloem reaction zone formed and monoterpenes accumulated in the phloem. These results suggested that O. canum was pathogenic to Yunnan pine and that the wide distribution of the fungus might be beneficial to reproduction of pine shoot beetles in Yunnan pine. However, because the reaction zone and monoterpene accumulation were mild, fungal damage of Yunnan pine might be limited. A more integrated study considering all the fungal species should be done to better understand the interactions among bark beetles, blue-stain fungi, and the tree hosts in the region.