Laboratory Evaluation of Beauveria bassiana ARP14 Against Grapholita molesta (Lepidoptera: Tortricidae)

Entomopathogenic fungi often have wide host range and can be important biological control agents against the oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), a significant pest of stone and pome fruits. The virulence of six entomopathogenic fungi, including three strains of Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Cordycipitaceae) (ARP14, GHA, A) and one strain each of Metarhizium robertsii Bischoff, Rehner, & Humber (Hypocreales: Clavicipitaceae), Metarhizium brunneum (Petch) (Hypocreales: Clavicipitaceae), and Isaria farinosa (Holmsk.) (Hypocreales: Cordycipitaceae) was assessed against first instars (< 5 h old) of G. molesta held in glass scintillation vials. Compared to commercialized strain of B. bassiana (GHA), B. bassiana ARP14, which was recovered from a cadaver of Riptortus pedestris (F.) (Hemiptera: Alydidae), killed first instar larvae 2.6 times faster at 12 h after exposure to 1 × 108 conidia/ml concentration at 95.9% RH and 25.4 °C. However, the mycosis rate after 14 days was similar to that of B. bassiana GHA in all treatments. Beauveria bassiana ARP14 also killed adult moths 2.7 (males) and 2.2 (females) times faster than did B. bassiana GHA, measured 168 h (7 days) after exposure. However, the mycosis rate after 14 days was similar from both fungi. In assay using three conidial concentrations (1 × 107, 1 × 108, and 1 × 109 conidia/ml) and three RHs levels (55, 75, and 95%). Mortality became higher as concentration and RH increase, but mycosis rate at 14 days wasn’t significantly different among treatments. These results suggest that B. bassiana ARP14 can be a potential biological control agent against G. molesta.