Sagwe R.N.,Jomo Kenyatta University of Agriculture and Technology |
Muya S.M.,Jomo Kenyatta University of Agriculture and Technology |
Maranga R.,Multimedia University of Kenya
Journal of Insect Conservation | Year: 2015
Habitat degradation poses a great threat to biodiversity conservation. Abundance and diversity of butterflies is an indicator of good environmental health. Understanding how different butterfly species respond to habitat degradation is a necessary step towards the development of effective measures to enhance environmental protection. This study investigated the impact of land use patterns on the diversity, abundance, and conservation status of butterflies in the Kisii highlands; a densely-populated region in Kenya that has received little attention in ecological studies. Sampling was done through a line transect of 300 m. A total of 2799 individual butterflies comprising 67 species were recorded across seven land cover types; secondary forest, grasslands, riverine, human settlement, mixed farmlands, monoculture, and mining areas. The secondary forest, riverine and mixed farmlands recorded more butterflies (37.0, 26.0, and 15.5 %, respectively), followed by grasslands (12.5 %), while monoculture, human settlements, and mines had the least number of butterflies (3.0 % each). Moreover, the secondary forest, riverine and mixed farmland land cover types were the most species rich. Nymphalidae were the most abundant (38 species) whereas, Papilionidae the least (3 species) in the region. Junonia sophia was the dominant species. Butterflies were most diverse in the secondary forest (Shannon–Weaver diversity index, H′ = 2.89), while the human settlement had the least (H′ = 1.25). One-way ANOVA analysis indicated a higher species similarity between secondary forest, mixed farming and riverine land cover types compared to a low species similarity between secondary forest and mining, grassland, monoculture and human settlement. Butterfly abundance and distribution was different between the dry and wet season among the land cover types. Therefore, land use patterns had effects on butterfly abundance and diversity and their conservation is threatened if proper management practices are not put in place. Planning of land use activities should thus encourage agro-forests/secondary forests interspaced with other land use activities to enhance environmental health and improve on biodiversity conservation. © 2015, Springer International Publishing Switzerland.
Onunga D.O.,Masinde Muliro University of Science and Technology |
Kowino I.O.,Masinde Muliro University of Science and Technology |
Ngigi A.N.,Multimedia University of Kenya |
Osogo A.,Masinde Muliro University of Science and Technology |
And 3 more authors.
Journal of Environmental Science and Health - Part B Pesticides, Food Contaminants, and Agricultural Wastes | Year: 2015
Carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate) has been used within the Nzoia River Basin (NRB), especially in Bunyala Rice Irrigation Schemes, in Kenya for the control of pests. In this study, the capacity of native bacteria to degrade carbofuran in soils from NRB was investigated. A gram positive, rod-shaped bacteria capable of degrading carbofuran was isolated through liquid cultures with carbofuran as the only carbon and nitrogen source. The isolate degraded 98% of 100-μg mL−1 carbofuran within 10 days with the formation of carbofuran phenol as the only detectable metabolite. The degradation of carbofuran was followed by measuring its residues in liquid cultures using high performance liquid chromatography (HPLC). Physical and morphological characteristics as well as molecular characterization confirmed the bacterial isolate to be a member of Bacillus species. The results indicate that this strain of Bacillus sp. could be considered as Bacillus cereus or Bacillus thuringiensis with a bootstrap value of 100% similar to the 16S rRNA gene sequences. The biodegradation capability of the native strains in this study indicates that they have great potential for application in bioremediation of carbofuran-contaminated soil sites. © 2015, Copyright © Taylor & Francis Group, LLC.
Ngigi A.,Multimedia University of Kenya |
Getenga Z.,Masinde Muliro University of Science and Technology |
Boga H.,Jomo Kenyatta University of Agriculture and Technology |
Ndalut P.,University of Eldoret
Bulletin of Environmental Contamination and Toxicology | Year: 2014
The s-triazine herbicide hexazinone [3-cyclohexyl-6-dimethylamino-1-methyl- 1,3,5-triazine-2,4(1H,3H)-dione], is widely used in agriculture for weed control. Laboratory biodegradation experiments for hexazinone in liquid cultures were carried out using sugarcane-cultivated soils in Kenya. Liquid culture experiments with hexazinone as the only carbon source led to the isolation of a bacterial strain capable of its degradation. Through morphological, biochemical and molecular characterization by 16S rRNA, the isolate was identified as Enterobacter cloacae. The isolate degraded hexazinone up to 27.3 % of the initially applied concentration of 40 μg mL-1 after 37 days of incubation in a liquid culture medium. The study reports the degradation of hexazinone and characterization of the isolated bacterial strain. © 2014 Springer Science+Business Media New York.
Mutua G.K.,Masinde Muliro University of Science and Technology |
Ngigi A.N.,Multimedia University of Kenya |
Getenga Z.M.,Masinde Muliro University of Science and Technology
Bulletin of Environmental Contamination and Toxicology | Year: 2015
Two organic amendments, filter mud compost and Tithonia diversifolia leaves generated within a sugarcane growing area were used to enhance the degradation of chlorpyrifos in soil. Filter mud compost and T. diversifolia leaves significantly enhanced degradation of chlorpyrifos in soils (p < 0.05) with DT50 values of 21 and 24 days, respectively. Furthermore, field degradation of chlorpyrifos in soil with prior exposure to chlorpyrifos was significantly enhanced (p = 0.034) with DT50 of 21 days compared to 30 days in soil with no previous exposure. Degradation of chlorpyrifos in sterile and non-sterile soils were significantly different (p = 0.023) with DT50 values of 161 and 27 days, respectively. Results show enhanced degradation of chlorpyrifos in organically amended soils and soils with prior exposure to the pesticide. These amendments show promise in a continuing effort to reduce chlorpyrifos concentrations in soils. © 2015 Springer Science+Business Media New York.
Wambua P.M.,Moi University |
Mayaka A.N.,Multimedia University of Kenya |
Odhong E.O.V.,Moi University
Research Journal of Applied Sciences, Engineering and Technology | Year: 2012
Thermoplastics are among polymers that biodegrades very slowly over a very long period and can be regarded as nonbiodegradable despite their rapid accumulation in the environment. The use of plant natural fibres as reinforcement for thermoplastics to produce composites is an important area for research. In this study, composites of high density polyethylene wastes reinforced with wood flour, rice husks and bagasse fibers were prepared. The fibers were heated to reduce their moisture content and improve their compatibilities with heated high density polyethylene wastes so as to increase adhesion at the interface. Binders were used to improve interfacial strength of the composite. Composites were prepared by extrusion. From preliminary laboratory test results based on Fratios using ANOVA, optimal coupon was found to be wood flour mixed with high density polyethylene and polyurethane resin (X 17) heated to 210°C and extruded at 140°C. The final test results for mechanical properties for optimal wood flour, rice husks and bagasse composites respectively were: Tensile strength; 83.87, 74, and 62.73 MPa. Flexural strength; 26.73, 39and 15.22 MPa. Compressive; 225, 190.5 and 140 MPa and Impact; 78, 81 and 66 J/mm 2. The use of binders significantly improved impact strengths and widely expanded the usage of such product to include light load structural applications thus offering alternative source of construction materials to supplement timber and hence save forests. The technology can create employment to thermoplastic waste collectors, fibre collectors and composite producers. © Maxwell Scientific Organization, 2012.