Pengaruh pH Larutan Buffer Dan Suhu Penyimpanan Terhadap Aktivitas Larvasida Bacillus sphaericus 2362

Widyastuti, Umi and Blondine, Blondine (2009) Pengaruh pH Larutan Buffer Dan Suhu Penyimpanan Terhadap Aktivitas Larvasida Bacillus sphaericus 2362. Buletin Penelitian Kesehatan, 36 (1). ISSN 0125-9695

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Abstract

. A study was conducted to determine 1). The effect of increasing pH buffer (4-10) and storage temperature (4oC) on larvicidal activity of B. sphaericus 2362, 2). The effect of increasing pH buffer (4-10) and storage temperature (25oC) on larvicidal activity of B. sphaericus 2362, 3) The interaction effect between increasing pH buffer and storage temperature on persistence of larvacidal activity of B. sphaericus 2362. This study was conducted from June-December 2005 and was done in two steps i.e. mosquito and larvae collecting (field evaluation) and mosquito and larvae rearing completed with bioassay (laboratory evaluation). B. sphaericus 2362 was stored in acid, neutral and alkaline buffers ranging from pH 4 to 10 at 4oC and 25oC, and was then tested on Anopheles aconitus, Culex quinquefasciatus, and Ae aegypti early fourth instar larvae. The test was conducted according to WHO standard guidelines periodically biweekly until 224 days. Larvicidal activity was calculated based on larval mortality after 48 hours of exposure. The results showed that bioassay test of B. sphaericus 2362 for 48 hours exposure within the concentration of 0.0098 ppm, 0.0035 ppm and 1.3232 ppm were respectively killed 95% of An. aconitus, Culex quinquefasciatus, and Ae aegypti. From each concentration showed that larvicidal activity of B. sphaericus 2362 which was stored in neutral buffer was proven to be longer compared to those which formerly stored in acid and alkaline on three species tested. Larvicidal activity of B. sphaericus (of more than 70%) stored at 4oC in neutral buffer (pH 7) was maintained longer than at 25oC on An. aconitus, respectively 112 days compared to 98 days and it is remained the same 224 days for Cx. quinquefasciatus and 70 days for Ae. aegypti. The best storage regime for maintenance of larvicidal activity of B. sphaericus on An. aconitus, Cx. quinquefasciatus and for Ae. aegypti larvae was 4oC in neutral buffer

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