Evaluating bacteria, fungi and viruses for controlling shoot borer (Cryptophlebia ombrodelta) damage in Erythrophleum fordii plantations in Vietnam

Abstract

Erythrophleum fordii has been prioritized for use in sawtimber production and forest restoration programs with native tree species in Vietnam. However, the shoot borer Cryptophlebia ombrodelta (Lower, 1898) (Lepidoptera: Tortricidae) is becoming a serious pest in E. fordii plantations. This study evaluated the potency of biological agents to control C. ombrodelta in laboratory and field experiments. Eight biological control agents (BCAs) were prescreened in a laboratory trial and the five most effective BCAs were evaluated in a one-year-old plantation. Spraying foliage with Bacillus thuringiensis var. kurstaki + granulosis virus or nuclear polyhedrosis virus at concentrations of 4 g/l and 4 ml/l, respectively, reduced damage from C. ombrodelta by over 70% compared to the water control. The findings can guide further research on the timing and frequency of applications of BCAs necessary to manage the pest in young stands of E. fordii.