FEMS Microbiology Letters (2010) 305, 155-161
Ramesh S. Hire, Ashok B. Hadapad, Narayanan Vijayalakshmi and Tanaji K. Dongre (2010)
Characterization of highly toxic indigenous strains of mosquitocidal organism Bacillus sphaericus
FEMS Microbiology Letters 305 (2), 155-161
Abstract: Three indigenous isolates of Bacillus sphaericus (ISPC-5, ISPC-6 and ISPC-8), along with standard 2362 and 1593 strains, were evaluated for spore viability and mosquitocidal activity. Among these, ISPC-8 was the most viable and virulent isolate, exhibiting a significantly higher total viability count (TVC) and lower LC50 values. The TVC of the standard strains ranged from 4.0 to 9.2 × 108 spores mL-1, whereas it was 1.3 × 109 spores mL-1 for ISPC-8. The LC50 values of ISPC-8, 2362 and 1593 against Culex quinquefasciatus were 0.68 × 103, 1.22 × 103 and 1.85 × 103 spores mL-1, respectively. The ISPC-8 was further assessed for host spectrum and found to be more active against C. quinquefasciatus, followed by Culex tritaeniorhynchus, Aedes albopictus and Aedes aegypti. The ISPC-8 strain was thus found to be a promising isolate for developing biopesticides. Among the indigenous strains, only ISPC-8 was found to have binary toxin genes (binA and binB). Comparative sequence analysis revealed that the BinA (41.9 kDa) protein of ISPC-8 differs by one amino acid (R197M), whereas BinB (51.4 kDa) differs by two amino acids (H99P, P174S) as compared with 1593 and 2362 strains. The purified binary proteins of ISPC-8 showed an LC50 value of 6.32 ng mL-1 against C. quinquefasciatus larvae after 48 h.
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Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution
evaluation - screening - selection
