ENHANCING THE VIRULENCE OF THE ENTOMOPATHOGENIC FUNGUS LECANICILLIUM AGAINST APHIDS BY MUTATION USING ULTRAVIOLET AND N-METHYL-N’-NITRO-N-NITROSOGUANIDINE FOR BIOPESTICIDE PRODUCTION
Vũ Văn Hạnh
Lê Thị Thùy Dương
Quyền Đình Thi
Nguyễn Thị Thu Thủy
Abstract
Fungi in the genus Lecanicillium are important pathogens of insects and some have been developed as commercial biopesticides due to its parasitic virulence. Among tested fungal strains, an entomopathogenic fungal strain L43 is highly virulent against peach aphids (Myzus persicae) that caused 100 % aphid’ mortality after 5 days conidia spraying, at 23 - 27oC and 75 – 85 % of relative humidity. The fungal strain L43 was identified as a strain belonging to genus Lecanicilliumand its 28S rRNA sequence showed 99.5 % of identities in comparison to those from ecanicilliumstrains deposited on GenBank. For improvement of virulence against aphids, protoplasts of Lecanicilliumsp.L43 were exposed to UV-irradiation (ultraviolet) and Vũ Văn Hạnh, Lê Thị Thùy Dương, Quyền Đình Thi, Nguyễn ThịThu Thủy 210 NTG (N-methyl-N’-nitro-N-nitrosoguanidine) to generate mutants. Among 42 mutants were screened, UV10.1, UV10.4 and UV60.3 (created by UV treatment), NTG30.2, NTG50.1, NTG50.2 and NTG60.2 (created by NTG treatment) showed 100 % mortality against M. persicaeafter 4 to 5 days of conidia spraying. The virulence of selected mutants was increased by 6 to 58 % compared to that of the widetype L43, at 25 - 29 oC và 75 - 85 % of relative humidity. These results suggested that mutants of Lecanicillium sp. L43 are precious resource for futher study and may have potential for development of an effective microbial control agent against