Beauveria bassiana- a potential mycopesticide for the efficient control of Coffee Berry Borer, Hypothenemus hampei (Ferrari) in India

Abstract

The Coffee Berry Borer (CBB), Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae) has been a serious insect pest of coffee cultivars C. robusta and C. catimor in India since 1991, causing 40-80% coffee bean loss. To combat this important pest, an indigenous entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin was isolated from dead and moribund coffee berry borers from the wild. The fungus was cultured on yeast extractpeptone supplemented liquid medium. The mycelial mat was harvested from 12-day old cultures and lyophilized. A suspension of the most virulent isolate (Bb2) was prepared in sterile water and used as a mycopesticide. The laboratory studies were conducted on coffee berry borers by applying conidial suspensions at a dosage rate of 1×10⁶ conidia ml⁻¹ . Pest mortality with the Bb2 isolate increased from 69.3% to 95.3% with an increase in relative humidity (RH) at 25 ± 2°C. Field experiments were conducted in a coffee plantation area in the Kodagu district of Karnataka, and the results showed that, under favourable environmental conditions (27-29°C; 82-91% RH; 10-15 inches rainfall per year), the fungus required only eight days to colonize and kill the target pest. A maximum of 75.6% insect mortality was recorded 24 days after spraying. Large-scale field trials conducted in five plantation plots between September 1995 and September 1998 showed significant insect mortality both in C. robusta and C. catimor cultivars of coffee. The potential use of this indigenous fungal strain of B. bassiana as a mycopesticide for management of CBB in India is discussed.