The impact of water quality on the efficacy an persistence of BACILLUS SPHAERICUS in c ontroling CULEX QUEFASCIATUS larvae

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Research type: Research Paper

Authors: Dafalla, Waheed Eldeen Elsideeg .

Abstract: The influence of water quality on the efficacy and persistence of B. SPHAERICUS STRAIN 2362 against C. QUINQUEFASCIATUS larvae was investigated in the laboratory. Bioassays were conducted with different dilutions of sewage water using different concentrations of B.SPHAERICUS. The impact of water quality was measured by larval mortality. Increasing concentrations of organic pollution in water resulted in higher LC50 & LC90 values. A linear relatonship was observed between organic content of the various dilutions and B.SPHAERICUS concentrations. NH3 - N and TKN as water parameter has significant effects on the C. QUINQUEFASCIATUS larvae mortality; i.e larve were reduced by more than 80 percent in samples with NH3-N ranged from 0.45 mg/l to 1.15 mg/l and TKN ranged from 0.83 mg/l to 2.28 mg/l when B. SPHAERICUS applied in a concentration of 0.06 mg/l, while mortality recorded less than 28 percent when NH3 - N and TKN more than or equal to 30.9 mg/l and 32.16 mg/l respectively using the same concentration of bacteria.B. SPHAERICUS persisted but in low level of control in the absence of dead larvae for 7 days (the maximum larval mortality reached was 21 percent).