The Occurrence of Entomopathogenic Fungi on Mineral and Peat Soils in Peninsular Malaysia

Abstract

The aims of this study are to isolate and identify Entomopathogenic Fungi (EPF) from mineral and peat soils in relation with the soil physico-chemical parameters. The mineral soil was sampled from the MPOB Research Station Hulu Paka in Terengganu, whereas peat soil was sampled from the MPOB Research Station Teluk Intan in Perak. Isolation of these fungi was carried out using a selective medium. Morphological characteristics of fungi were studied by observing the mycelium and conidia grown on agar plates using a light microscope. Soil physico-chemical parameters such as pH, water content, carbon and nitrogen content were also determined. Two species of EPF isolated from both types of soils were identified as Isaria amoenerosea and Metarhizium anisopliae. On potato dextrose agar, the colony of I. amoenerosea was pink in colour and slow growing with floccose mycelium which producing conidiophores with 3 to 4 phialides. The conidia were subglobose or irregular shapes between 2.0-3.0 µm long × 1.7-2.0 µm wide. The colony of M. anisopliae was whitish yellow and turned to dark green when matured; slow growing with floccose mycelium. The conidia were cylindrical with the dimension ranging from 6.0-7.0 µm long × 2.0-2.8 µm wide. The result shows that the occurrence of I. amoenerosea was more dominant than M. anisopliae. In mineral soil, out of 30 samples, I. amoenerosea was isolated from 25 soil samples (83%), while the M. anisopliae was only found in 15 samples (50%). In peat soil, out of 36 samples collected, 26 samples (72%) were found with I. amoenerosea, while the fungus M. anisopliae was isolated from eight samples (22%). In this study, the occurrence of EPF on mineral soil was higher than from peat soil, which was possibly due to low water content, high soil temperature and low C/N ratio.