Isaria javanica (anamorphic Cordycipitaceae) isolated from gypsy moth larvae, Lymantria dispar (Lepidoptera: Lymantriidae), in Japan

Abstract

An entomopathogenic fungus, Isaria javanica (anamorphic Cordycipitaceae) was isolated from diseased larvae of the gypsy moth, Lymantria dispar, in outbreak populations from Iwate Prefecture, in northern Japan in the summer of 2008. The fungus caused a mixed infection with Entomophaga maimaiga in the gypsy moth populations. The fungus forms conidial chains on phialides verticillate on conidiophores, with conidia fusiform to oval, 3.0-4.3-6.3× 1.4-2.0-3.2 μm, chlamydospores and synnemata absent, and grows on SDAY medium at 10-30°C, with optimal growth at 25°C. Phylogenetic analyses, using the β-tubulin gene and internal transcribed spacer (ITS) rDNA, positioned the fungal isolates to a well supported branch where I. javanica was included. The dipping of larvae into the conidial suspension revealed a moderate virulence of the fungus to the gypsy moth (mortality 58-100% with 108/ml). This is the first discovery of I. javanica on L. dispar larvae.