Isolation of entomopathogenic fungi from cultivated and uncultivated soils and evaluation of virulence against cowpea beetle, Callosobruchus maculatus (F.) (Coleoptera:Chrysomelidae)

Abstract

We aimed to explore the entomopathogenic fungi (EPF) from the different ecosystems including forests, gardens, fields, and rangeland soils in Kermanshah province, Iran. Trials were carried out on morphological, molecular characterization, diversity indices, and virulence assessments of indigenous EPF from 41 sampling sites of various localities. Using the Ephestia kuehniella (Zeller) as host bait, 114 fungal isolates were recovered-i.e., 39 from forests, 38 from fields, 22 from rangelands, and 15 from garden soils. Based on morphological features and the sequence analysis of the internal transcribed spacer (ITS) of the ribosomal DNA, the recovered entomopathogenic fungi were identified as Alternaria chlamydosporigena, Aspergillus nomius, Beauveria bassiana, B. pseudobassiana, B. brongniartii, Chaetomium elatum, Fusarium equiseti, F. oxysporum, Fusarium sp., Meyerozyma guilliermondii, Paramyrothecium roridum, Penicillium sizovae, P. solitum and Penicillium sp.. Higher species richness was found in the oak forest soils compared with fields, gardens, and rangelands. Additionally, the oak forest soils had high values of diversity indices, i.e., Simpson Ds (0.97), Shannon (3.30), Equitability (0.69), and Fisher's alpha (25.8). The dominance index was higher in the rangelands compared with the others. Following the priliminary assays, the insecticidal activity of three selected EPF isolates, including Beauveria brongniartii, B. bassiana, and B. pseudobassiana was tested against adults of the cowpea beetle, Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae: Bruchinae) as host. Hypervirulent strains caused high mortality considered as promising effective biocontrol agents in insect pest management programs.