Assessment of Bioactivity of Se-lected Plants against Pests and Microbes from Agro-pastoral Communities in Mbulu District, Tanzania

Michael , Qwarse (2015) Assessment of Bioactivity of Se-lected Plants against Pests and Microbes from Agro-pastoral Communities in Mbulu District, Tanzania. Masters thesis, The Open University Of Tanzania.

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Abstract

This study intended to have an ethnobotanical inventory of medicinal and pesticidal plant species and their bioactivities and toxicity against selected bacteria, fungi and storage pests. Bioactivities (antimicrobial and antioxidant activities) against disease causing organisms, toxicity against brine shrmps, first filial generation (F1) progeny, feeding deterrence and repellence against selected storage pests and quality grains evaluation as well as phytochemicals profiles were determined using standard proce-dures. A total of 66 dentifies plant species mainly from Minosoidaceae, Solanaceae, and Euphobiaceae families were used for pesticidal and medicinal purposes with oral route as the main route of administration and leaves as commonly used plant parts. Antibacterial activities of selected plants were between 25% and 75% of the activity of gentamycin sactivity. Antifungal activities of selected plant species varied from 0% to 55 % of the fluconazole activity. Antioxidant activity of Phytolacca dodecan-dra roots measured by percent absorbance was 90% as compared to 98% of the Bu-tylated Hydroxy Toluene (BHT) activity. Brine shrimp cytotoxicities ranges of P. dodecandra, (LC50 = 4.6 – 34.7 μg/mL), Cynoglossum geometrium (LC50 = 71.09 μg/mL) and Ocimum filamentosum (LC50 = 28.08 μg/mL) are indicate potential cyto-toxicity of plants. P. dodecandra leaf extracts killed 98% of Sitophilus zeamais and 99% of Tribollium castaneum at concentration of 150 mg/mL on day 3. Similarly, P. dodecandra leaf extracts reduced grain damage to 0% and had moderate repellence of 57% and 66% to Sitophilus zeamais and Tribollium castaneum, respectively. Little effects of leaf extracts on the grain quality (seed damage, colour and odour) was ob-served. Seed viability decreased to about 30% after 90 days. Isolation and structure elucidation of bioactive ingredients in selected plant species is recommended.

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