The occurrence and pathogenicity of Geosmithia spp. and common blue-stain fungi associated with pine bark beetles in planted forests in Israel

Abstract

Fungi associated with the bark beetles Orthotomicus erosus, Tomicus destruens and Pityogenes calcaratus were sampled in various pine forests throughout Israel. Three ophiostomatoid fungi, Ophiostoma ips, Graphilbum rectangulosporium and Leptographium wingfieldii, and a fourth non-ophiostomatoid fungus, Geosmithia sp. 24, were identified by using morphological characteristics and molecular genetic analyses. O. ips, the most common fungus, was mainly isolated from O. erosus. The least common fungus, G. rectangulosporium, was frequently isolated from all three studied scolytids, while L. wingfieldii was almost exclusively associated with T. destruens. The fourth fungus, Geosmithia sp. 24, was isolated from both O. erosus and P. calcaratus. This is the first time that an association between O. erosus and a Geosmithia sp. has been reported. Our findings also suggest that Geosmithia sp. 24 can be separated into two distinct sub-groups by molecular analyses. Pathogenicity was demonstrated only for L. wingfieldii, both on Aleppo and brutia pine, exclusively under controlled conditions (25 ± 5 °C) but not at elevated temperatures.