Isolation and identification of entomopathogenic fungi and an evaluation of their actions against the larvae of the fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae)

Abstract

In China, the fall webworm, Hyphantria cunea, causes enormous losses. The potential of entomopathogenic fungi (EPF) to control pest insects has been demonstrated in the laboratory and the field. In this study, we isolated and identified EPF from the surfaces of H. cunea larvae cadavers, and we investigated their efficacy against fall webworm larvae under bioassay conditions in the laboratory. Isaria javanica BE01 conidial suspensions with concentrations between 1 × 10⁴ and 1 × 10⁸ conidia ml⁻¹ were shown to have marked effects on the larval mortality (the 3rd, 4th, and 5th instar larvae) over a 15 days period. However, the effect of the instar on the mortality was not always significant, except during the late stages (10–14 days) at low concentrations (1 × 10⁴–1 × 10⁶ conidia ml⁻¹) or the early stages (1–5 days) at high concentrations (1 × 10⁷–1 × 10⁸ conidia ml⁻¹). Otherwise, the mortality of the 3rd and 4th instar larvae exceeded 85% at 1 × 10⁸ conidia ml⁻¹. The present study suggests that I. javanica BE01 is a potential biological control agent of H. cunea.