Laboratory and Field Susceptibility of Drosophila suzukii Matsumura (Diptera: Drosophilidae) to Entomopathogenic Fungal Mycoses1

Abstract Spotted wing drosophila (Drosophila suzukii Matsumura; Diptera: Drosophilidae) is a recently established invasive insect pest of berries and stone fruits. We tested the susceptibility of adult D. suzukii to infection by four species of entomopathogenic fungi: Beauveria bassiana (Bals.) Vuill., strains GHA and HF-23; Isaria fumosorosea Wize, strains FE-9901 and Apopka 97; Metarhizium anisopliae var anisopliae (Metschn.), strain F-52; and Metarhizium robertsii, strain DW-346; in laboratory bioassays. Scanning electron micrographs confirmed germination of conidia on D. suzukii integument. Exposure to conidia of all fungal isolates significantly increased mortality rates in comparison to untreated flies. In a subsequent bioassay of the two most virulent isolates, increasing pathogen dose from 0–16,000 conidia mm−2 of B. bassiana strain GHA increased fly mortality and proportion of sporulating cadavers. While fly inoculations with M. anisopliae at 0–4000 conidia mm−2 did not yield any measurable morta...