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20111
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Subject: Zoology × Author: Geroh, Monika × End date: 2018 × Start date: 2010 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Molecular characterization of Beauveria bassiana (Balsamo) vuillemin and its bioefficacy against Tetranychus urticae Koch (Acari: Tetranychidae)
    (CCSHAU, 2011) Geroh, Monika; Gulati, Rachna
    Investigations were carried out to assess the pathogenicity of Beauveria bassiana against Tetranychus urticae on okra. Molecular characterization of six strains of B. bassiana was done by RAPD- PCR to know the genetic similarity among them. The yield of genomic DNA of B. bassiana was higher in Lysis Buffer method (2.10 to 10.50μg/ ml) as compared to CTAB method (2.34 to 7.10μg/ ml). Absorbance ratio of all strains varied from 1.60 to 2.20. Eleven random primers generated 19 (82.16%) polymorphic and 4 (17.39%) monomorphic bands. The size of PCR amplified products ranged from 500 to 4000 bp. The genetic similarity of the strains varied from 50 to 70 percent. Under in vitro 42 to 94 and 34.1 to 66.25 percent mortality of T. urticae was recorded in Direct Spray and Treated Food Bioassay, respectively with 1 × 105 to 1 × 1012 conidia ml-1 conecntrations of B. bassiana. LC50 values of B. bassiana were in the range of 3 × 105 to 2.6 × 1011 conidia ml-1 and LT50 values varied from 52.12 to 141.53 h for eggs, larvae, nymphs and adults in both the bioassay methods. Direct Spray Bioassay was more effective as compared to Treated Food Bioassay. Under field conditions, the percent reduction in T. urticae was from 51.03 to 65.18 percent with all the strains. Hb- Hyderabad (65.18%), was the most potent in reducing the mite population followed by ITCC- 4668 (62.36%), ITCC- 5408 (58.55%), ITCC- 6063 (54.61%), ITCC- 5549 (52.48%) and ITCC- 4513 (51.03%). There was no effect of B. bassiana spray S. punctillum population as their numbers in B. bassiana (strain Hb- Hyderabad) treatments (1.43 beetles/ leaf) and control (1.17 beetles/ leaf) were statistically comparable. Higher yield of okra fruits was recorded in B. bassiana treated plots (581.43 g/ plot) as compared to untreated plots (577.66 g/ plot). The Chlorophyll content was also higher in B. bassiana treated leaves (0.289 to 0.492 μg/ ml) as compared to untreated plots (0.166 μg/ ml).