Entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana as potential biological control agents of Coelaemenodera elaeidis of the oil palm (Elaeis guineensis Jacq.)

Abstract

The potential of two entomopathogenic fungi Metarhizium anisopliae.and Beauveria bassiana for the control of Coelaemenodera elaeidis were evaluated. The objective of this study was to control C. elaeidis using entomopathogenic fungi as biocontrol agents. The pathogenicity of M. anisopliae and B. bassiana isolates were tested using direct contamination bioassay set up of 2.5 g conidia (2.5 g of Metarhizium 2.5 x 10 10 or 2.5g of Beauveria 10 11) transferred to the centre of plastic Petri dishes. Results from M. anisopliae studies indicated that C. elaeidis changed from yellow to brown and darker brown colour. Death of C. elaeidis was observed on the fourth day post incubation with 100% mortality and the control treatment recorded 14% mortality. C. elaeidis were observed with white mycelia growth on the ninth day, the green conidia appeared around the cadavers. Using B. bassiana, ingestion of spores caused infection from the mandible which spread to the thorax. Infection spread beneath the thorax colonizing the abdomen with white mycelia growth. Death was observed on C. elaeidis with 100% mortality on the sixth day post incubation. The larvae and pupae recorded deaths on the eighth and eleventh days post incubations with 100% each. The control treatment recorded mortalities at 21% for larvae and 7% for pupae. The study results indicated that both M. anisopliae and B. bassiana have a high potential as biocontrol agents for the control of C. elaeidis.