Characterization of Isolates of Beauveria bassiana (Balsamo) Vuillemin Collected from Three States of Southwest Nigeria

Abstract

Beauveria bassiaana is a soil borne fungus with variations in molecular composition across varying locations. Ten isolates of B. bassiaana isolated from soil samples collected from forest sites in three States of Southwest Nigeria were characterized using morphological and molecular tools. The morphological characteristics considered were radial growth, colour of colonies, texture, shape of the spores and filaments and the relationship of the spores to the filaments.Means were separated using Duncan’s Multiple Range Test at 0.05% level of significance. DNA was extracted from the isolates and results from the OTU clustering were sequenced using ITS1 and IT4 primers. Results showed slight variation in colour of the colonies, varying from whitish cream to white, having smooth, powdery textures with colonies becoming more identical as plates extended with no significant differences in texture and elevation of the colonies. The radial growth of the isolates was fast, with complete plate cover of the 9 cm Petri dish plates within 7 days for all the isolates. Images of the conidia as viewed under the microscope at x10 and x100 magnifications were observed to possess conidiophores that have whorl and dense clusters of symphodial, short and globose conidiogenous cells with apical zigzag appearance and one celled spherical conidia that prevents any variation in colonies. Isolate sequences showed a 100% homology to B. bassiana having molecular character variations with isolates 6, 4, 9, 3, 2 having percentage similarity of 99.86 with B. bassiana with accession no BbN06B02, isolate 5 had a percentage similarity of 90.62 with B. bassianawith accession number MW633220.198-48 and isolates 7 and 8 had a percentage similarity of 99.18 with B. bassiana with accession number AY805547.1:180-346 as represented in the dendrogramic tree. These observed variations could be utilized in biological insect pest management.