Browsing by Author "Anyika, D."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Characterization of various Bacillus thuringiensis strains having larvicidal activity on Chilo partellus first-instar larvae, after culture on cost-effective medium, in Kenya
    (2011) Anyika, D.; Boga, Hamadi I.; Mwirichia, Romano K.
    Bacillus thuringiensis strains are widely used in many larvicidal pest control programs. However, the large-scale production of these biolarvicides is very expensive due to the high cost of the production synthetic medium. In this study, we developed cost-effective media, based on locally available raw materials namely legumes, potato, and whey. The optical density, protein concentration yield, sporulation and Chilo partellus larvicidal action were studied by growing bacterial strains in these waste product and in comparison with the conventional medium (NYSM). Protein concentration yield of 27.60 μg/ ml, spore count of 5.60 × 108 and Chilo partellus larvicidal activity (LC50) of 78 μg/ l against first-instar larvae were obtained with a 72 h culture of this bacterium. Production of Bt Insecticidal Crystal Proteins in NYSM was comparable to the test media and mean values were not significantly different for spore counts: F (media) = 25.19 P>0.01. One-way ANOVA (repeated measures) difference in percentage larval mortalities of Bacillus thuringiensis subspecies kurstaki (F = 26.88, P>0.05) and Bt isolates was not statistically significant. The SDS-PAGE profiles indicated that spore-crystal product from each treatment consisted of proteins with molecular weights of approximately 110-120 kDa and 60-70 kDa. Therefore the investigation suggests that legume, potato and whey-based culture media are more economical for the industrial production of Bt Insecticidal Crystal Proteins.
  • Thumbnail Image
    Item
    Development of cost-effective media for the culture of Chilo partellus larvicide in Kenya
    (Academic Journals, 2013-03) Anyika, D.; Boga, Hamadi I.; Mwirichia, Romano K.
    Stem borers (Chilo partellus) are important field insect pests of maize (Zea mays L.) and sorghum (Sorghum bicolor L.) in Africa. They account for more than 30% yield losses depending on the composition of the pest community. C. partellus larvicide like Bacillus thuringiensis have been widely and effectively used in C. partellus control programs, but the industrial production of theses bacilli is expensive. Here we have attempted to develop three cost-effective media, based on legumes, potato, and whey. Growth and production of the insecticidal proteins from these bacteria were satisfactory; protein concentration yields of 27.60 mg/ml, spore counts of 5.60 × 108 CFU/ ml and first-instar Chilo partellus larvicidal activity (LC50) of 78 μg/l were obtained with a 72 h culture of this bacterium. Therefore, this investigation suggests that legume, potato and whey-based culture media are more economical and effective for the industrial production of B. thuringiensis insecticidal crystal proteins.