Aedia leucomelas (Lepidoptera: Noctuidae)–pathogenic Entomophaga aulicae (Zygomycetes: Entomophthorales) in sweet potato fields

Abstract

Entomopathogenic fungi have high potential in pest management; however, little attention was given to phylum Zygomycota (order Entomophthorales). Herein we investigated the ecology of Entomophaga aulicae at three sweet potato fields (Iksan, Wanju, and Gimje) in Korea and further characterized its biological features, finally suggesting the possible factors inducing the occurrence of the fungal pathogen, which can be effectively used as a biological control agent. In 2002, E. aulicae were primarily observed in Aedia leucomelas (sweet potato leaf worm) larval populations (average infection rate=41.3%). Further investigation at Iksan and Gimje in 2004 and 2005 showed that this fungal epizootic mostly occurred during the autumn season and the occurrence was related to precipitation. From the laboratory characterization, the fastest mycelial growth and the highest number of satellite colonies were observed at 20–24°C on Sabouraud dextrose agar with 1% yeast extract medium (SDAY). E. aulicae produced large amounts of protoplasts within this temperature range; the production was significantly enhanced when the medium contained fetal bovine serum (FBS). This work provided useful information about E. aulicae and suggests that this isolate can be an effective biological control agent against the serious sweet potato leaf worm.