Evaluation of Endophytes Associated With Maize and Entomopathogenic Fungi Against the Spotted Stem Borer, Chilo Partellus
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Date
2019-01-02
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Addis Ababa University
Abstract
Larvicidal effect of maize endophytes isolated from root and stem of maize and pathogenicity of selected entomopathogenic Beauveria spp. and Metarhizium spp. isolates against C. partellus were studied. Among 39 maize endophyte isolates screened for insecticidal activity, 11 isolates (8 bacteria and 3 fungi) showed larvicidal activity against C. partellus. Pathogenicity of crude extracts of the 11 isolates significantly varied in mortality ranging from 4.79% to 50.26%. The Isolate aaueb-11 under the genus Bacillus produced the highest mortality (50.26%) which was at the same significance level to the positive control Bt. Kurtsaki (60.13%). Eight EPF isolates were selected from 27 isolates and there was a significance variation in causing mortality against larvae of C. partellus. EPF isolates APPRC-34GM, S#10H and APPRC-44BC were the most virulent strains with mean percent mortality of 81.39%, 90.00% and 90.00% respectively. Lethal time and lethal concentrations required to kill 50% and 90% of the experimental insects of the most virulent EPF strains were also determined. The isolate S#10H showed relatively short time to kill 50% of the population where the highest time recorded was 6.15 days. There was a general increase in LT50 with decrease in conidial concentration. The highest dose of the isolate S#10H, required to kill 50% and 90% of the larval population were 5.95x104 and 2.2x107 conidia per ml, respectively. The effective isolates could be a promising biocontrol agent against larvae of C. partellus. However, the specific compound contributing on the insecticidal activity from the crude fermentation extracts of endophytes need insecticidal spectra study and further isolation and purification to incorporate in microbial based biopesticide development. Thus, the active ingredients and compound structures should be further studied.
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Maize Endophyte, Chilo Partellus, Entomopathogens, Insecticidal Activity