STANDARDIZING GROWTH CONDITIONS FOR CONIDIATION OF ENTOMOPATHOGENIC STRAINS OF BEAUVERIA BASSIANA (BALS.) VUILL. AND EVALUATION AS BIOPESTICIDE
Loading...
Date
2012
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
PAU
Abstract
Thirteen fungal species were isolated from field soils of Punjab on Beauveria specific selective medium (BS-medium). Molecular screening of these strains using PCR amplification with B. bassiana specific primer set P1-P3 resulted in amplification of expected 524bp DNA band from only three strains (now named as BbR1, BbR2 and BbR3) and reference BbM1 strain (B. bassiana MTCC 2028), establishing only these to be true B. bassiana strains. Comparative RAPD-PCR amplification with 10 different RAPD primers identified many polymorphic markers which established that all the three strains were different strains. Genetic relatedness dendrogram as developed using RAPD-PCR data by UPGMA measured the quantitative description of genetic diversity. B. bassiana strains achieved their maximum growth during optimum incubation period of seven days. The optimum pH and temperature for maximal growth of B. bassiana strains was found to be 6-7 and 25-30ºC, respectively. All the tested carbon and nitrogen sources supported growth and development of the B. bassiana strains. Starch and peptone as carbon and nitrogen sources supported maximum radial growth and conidiospore count. Strain BbR2 was the fastest growing strain on almost all nutrient sources studied and possessed commendable growth rate and sporulation potential. Wheat bran (WB) and rice bran (RB) in the proportion of 3:1 supported maximum conidiospores yields (1.90×107 conidia/ml) for strain BbR2 in solid state fermentation conditions. Significant mortality of S. litura was observed at all the tested concentrations of conidial suspensions (103 to 107 conidia/ml) of B. bassiana and conidial concentrations of 106 and 107 conidia/ml being statistically at par with each other in causing maximum mortality. In comparison, under similar conditions, the standard strain BbM1 caused only least mortality (67.12%) and was significantly poorest in bio-efficacy amongst all the strains. In this study, B. bassiana strain BbR2 was concluded to be most potential locally isolated strains both for growth and conidiospore production as well as for causing maximum mean mortality (83.33%) of S. litura followed by BbR1 (72.22%), BbR3 (74.33%) which were better than the standard BbM1 strain.
Description
Keywords
null