http://localhost/xmlui/handle/123456789/1292 2026-10-06T20:15:40Z http://localhost/xmlui/handle/123456789/7136 Efficacy of Endophytic Fungi in the Management of Spoladea recurvalis (Lepidoptera: Crambidae) on Amaranth (Amaranthus dubius) Nyamamba, Druscilla Obonyo Amaranth is a Traditional African Vegetable (TAV) that in recent years has gained global popularity due to its exceptional nutritional, medicinal and economic attributes. However, its production is significantly limited by insect pest infestations, mainly lepidopteran defoliators. Spoladea recurvalis, commonly known as Hawaiian beet webworm has been reported as the major pest that feeds voraciously on the leaves leading to substantial yield losses of up to 100% under severe pest infestation. Chemical control remains a widely used method for the management of S. recurvalis. The use of fungal endophytes has emerged as a promising, sustainable and eco-friendly alternative to chemical pesticides in the management of insect pests. Therefore, this study evaluated the efficacy of selected 15 fungal isolates to endophytically colonize Amaranthus dubius host plant. Only two fungal isolates Hypocrea lixii F3ST1 and Trichoderma asperellum M2RT4 were found to be endophytic to A. dubius with varied colonization rates among them. The results revealed that both endophytes successfully colonized over 90% of all the examined plant tissues (root, stem and leaves). The two fungal isolates were further evaluated for their endophytic persistence, effect on host plant growth promotion and insecticidal activity against S. recurvalis life cycle and F1 progeny. Also, the behavioral and chemical mechanism through which the presence of the most potent endophytes H. lixii F3ST1 and T. asperellum M2RT4 within amaranth plants influence S. recurvalis host selection and herbivory were investigated. Both endophytes persisted in the host plant throughout the four-week assessment period exhibiting varying colonization rates influenced by significant interaction between time, fungal isolates and plant parts. Although T. asperellum M2RT4 outperformed H. lixii F3ST1 in the weekly assessment on plant growth promotion, the two endophytes significantly improved plant height, the number of leaves, leaf length and leaf width. Trichoderma asperellum M2RT4 significantly enhanced dry shoot biomass when compared with H. lixii F3ST1 and the control. Further, both endophytes significantly reduced number of egg masses laid, egg hatchability, increased larval mortality, reduce pupae formation, adult emergence and reduced survival/longevity of F1 progeny. Amaranthus dubius plants endophytically colonized by H. lixii F3ST1 significantly recorded the lowest number of egg masses (3.75 ± 1.11) resulting in 5% and 49.8% reductions, followed by T. asperellum M2RT4 (36.75 ± 3.77) compared to (73.25 ± 5.14) in the control. Upon egg hatching, H. lixii F3ST1 endophytically colonized plants significantly recorded the lowest number of larvae (13.75 ± 1.75) followed by T. asperellum M2RT4 (94.5 ± 11.66) compared to 196.5 ± 22.14 in the control. There was no significant difference in larval mortality by H. lixii F3ST1 endophytically colonized (40 ± 0.82%) and T. asperellum M2RT4 plants (42 ± 0.74%) compared to (2.91 ± 0.29%) in the control. Fewer pupae were obtained in H. lixii F3ST1 (3.75 ± 1.75) followed T. asperellum M2RT4 (44.5 ± 1.94) compared to 76.25 ± 1.43 in the control. Besides, adult emergence of S. recurvalis varied significantly between the fungal isolates with the lowest number of moths emerging from H. lixii F3ST1 endophytically colonized plants (3.25 ± 0.25) followed by T. asperellum M2RT4 (38.5 ± 1.19) compared to the control (66.5 ± 2.25). Furthermore, the two endophytes H. lixii F3ST1 and T. asperellum M2RT4 significantly reduced the survival of S. recurvalis F1 progenies. The behavioral bioassay using the Y-tube olfactometer revealed that S. recurvalis showed a preference for non-colonized amaranth plants over those colonized by both endophytes. Nevertheless, the findings showed that S. recurvalis moths were not attracted to either infested non-colonized or infested endophyte-colonized amaranth plants. Gas chromatography-mass spectrometry (GC-MS) analysis of volatiles emitted from non-inoculated, inoculated, non-inoculated infested, and inoculated infested amaranth plants colonized by H. lixii F3ST1 and T. asperellum M2RT4 revealed the presence of 80 and 74 volatile organic compounds (VOCs), respectively. Similarity percentage analysis highlighted the major compounds contributing to the differences observed among treatments. In H. lixii F3ST1-colonized plants, key discriminating VOCs included (Z)-3-Hexenyl acetate, pentadecane, α-Cedrene, o-Xylene, and (E)-β-Ocimene while for T. asperellum M2RT4-colonized plants, predominant differentiating compounds were Germacrene D, (Z)-3-hexenol, 1,3-Dimethylbenzene, Tetradecane, and 2,4,4-Trimethyl-1-pentene. The distinct VOC profiles linked to their colonization and treatment status suggest that these endophytes may influence plant defense signaling pathways, further contributing to their biocontrol efficacy for the management of S. recurvalis. Hence, providing insights for their integration into environmentally friendly pest management strategies in amaranth cropping systems. However, further studies are warranted to assess the effects of the key identified synthetic compounds on the pest and validate the results under field conditions. Master of Science in Plant Health Science and Managemen 2026-09-29T00:00:00Z http://localhost/xmlui/handle/123456789/7117 Black Soldier Fly (Hermetia illucens) Larval Meal for Broiler Chicken Feed: Effect on Growth Performance, Profitability, and Gene Expression Rotich, Victor Kiplangat The African poultry industry is characterized by high feed prices due to the limited availability of sufficient, high-quality protein. This has led to significant shortages, driving up the costs of poultry products and stagnating the sector's growth. Protein is the most expensive component of poultry feed, and its quality and availability are the limiting factors. This study investigated the effects of black soldier fly (Hermetia illucens L.) larvae meal (BSFLM) on growth performance, profitability and gene expression in 200 Ross 308 broiler chickens. Soybean meal (SBM) and fishmeal (FM) were substituted with varying levels of the BSFLM, resulting in five dietary treatments: SBM only, FM only, FM + BSFLM (1:1), SBM + BSFLM (1:1), or BSFLM only. Growth rates, organ weights, immune genes; interleukin-2 (IL-2), interleukin-6 (IL-6), tumor necrotic factor alpha (TNF-α), interferon-gamma (IFN-γ) and growth-related genes; chicken growth hormone (cGH), insulin growth factor 1 (IGF-1) expression were measured by quantitative Polymerase chain reaction (qPCR). Our results demonstrate that birds fed FM+BSFLM had significantly higher final body weight (p < 0.001), average daily weight gain (p < 0.001), and a low feed conversion ratio (p < 0.001). Birds fed FM+ BSFLM had significantly higher carcass weight (p = 0.026), while those fed SBM only yielded the lowest carcass weight. There were no significant differences in all the profitability parameters across the five treatments. The IL-2, IL-6, TNF-α, IFN-γ, IGF-1 and cGH gene expressions were significantly upregulated in the liver and spleen of birds fed diets containing BSFLM. Growth-related genes (cGH) positively correlated with live weight, body weight gain, and ADG. In conclusion, BSFLM at partial inclusion levels enhances broiler growth without significantly affecting profitability. Additionally, the inclusion of BSFLM in broiler diets upregulates the expression of genes associated with growth and immunity, leading to improved productivity in broiler production. It is recommended to use BSFLM as a partial replacement for soybean and fishmeal to improve growth and immune gene expression in broiler chickens. Keywords: black soldier fly larvae meal, profitability, immune modulation, gene expression, and poultry nutrition. Master of Science in Animal Nutrition 2026-08-26T00:00:00Z http://localhost/xmlui/handle/123456789/7113 Heavy Metals and Pathogen Content on Soil, Water and Produce in Urban Agriculture of Nairobi City Njenga, John Ng’ang’a Urban and peri-urban agriculture in Nairobi City County (NCC) is growing as a means of income generation, employment, nutrition and food security. However, environmental health risks outweigh urban agriculture practices in the city, as evident from widespread pollutant sources such as garbage dump site heaps, burst raw sewage pipes, contaminated wetlands, industrial effluent, and motor vehicle exhaust. Consumers are increasingly aware of the importance of buying safe food, and therefore urban agriculture practitioners must be informed on the safety status of their produce in order to adjust to good agricultural practices and take full advantage of the easily accessible consumer food market. The objectives of this research were to assess heavy metal incidence in inputs and food crops for urban farms in eastern zone of Nairobi, determine microbial incidences in food crop produce from farms, determine differences in element uptake by the crops, and to examine influence of environmental quality of the surrounding spaces on crop produce safety. A purposive sampling of farmers who grew any of the three target crops namely arrowroot (Colocasia esculenta L.), kale (Brassica olerasii var.Acephala L.) and tomatoes (Lycopersicon esculentum Mill.) was conducted of which ninety five farmers were identified. To focus on the critical regions of the city and with the guidance of Sub-County Agricultural Officers, three sub-counties of Starehe, Kamukunji and Kasarani, in the Eastern part of Nairobi City County were selected. Farm plots that met the criteria for the three target crops were identified (Starehe 4, Kamukunji 7 and Kasarani 4). From each of the 15 farm plots, samples of tomatoes, arrowroots, kales, water and soil were obtained with three replications per farm, following standard procedures for sample collection. Farmer’s immediate environment (neighbourhoods) were classified according to three pollution levels low, moderate, and high that were classified based on source and type of inputs and the condition of the environment surrounding the farm plot. Contents of cadmium, manganese, zinc and lead were analysed using Atomic Absorption/Flame Emission Spectrophotometer. Microbial analysis on irrigation water and the three produce was done to test for presence of salmonella, shigella and Escherichia coli bacteria. One way ANOVA was applied (i) to examine differences in means of heavy metals between locations and to compare transfer factor (TF) index of the crops and (ii) to examine differences on occurrence of the pathogenic microbes. Elements that were above allowable limits in the crops were Cd, Mn, Pb and Zn in arrowroots; Cd and Mn in kales and Cd, Mn and Pb in tomatoes. Cadmium content was highest in farm plots within Kasarani (2.44±0.86 mk/kg) and was significantly different from other two locations (p<0.05, Tukey HSD test). Between the neighbourhood qualities, heavy metal contents were different but not significant (p>0.05) between classes. The mean TF index for the heavy metals decreased in the order Cd>Pb>Zn>Mn. A transfer factor index of > 1 for cadmium was recorded in arrowroots, kales, and tomatoes. Overall, the highest mean of E.coli bacteria count was recorded in arrowroots at the Kamukunji sub-county (P=0.002). Between neighbourhoods, E.coli was significantly higher in irrigation water and arrowroots in the low-quality neighbourhoods (p<0.05). Kamukunji had the highest occurrence of Salmonella in irrigation water and arrowroots at 40%. There was no significant difference between neighbourhood classes in the prevalence pattern of Salmonella. The sub-county also had the highest prevalence of Shigella in irrigation water, at 20%. The overall mean rate of occurrence of Shigella was highest in irrigation water and in kales, at a rate of 17% in both cases. Compared to the other sub-counties, Kasarani had a much higher prevalence of Shigella in tomatoes with a significant difference in distribution pattern (p=0.001). Based on FAO/WHO standards, the measured heavy metal contents were high enough to cause health risk concerns. Produce from areas designated as of low environmental quality was not necessarily contaminated, as perceived. Urban agriculture producers in Nairobi need technical risk reduction technologies and legislative support to guarantee quality produce and valuable participation in the urban food system framework. It is recommended that future studies diversify crop types and localities and enhance collaboration between stakeholders. MSc in Horticulture 2026-08-31T00:00:00Z http://localhost/xmlui/handle/123456789/7080 Physicochemical, Nutritional and Functional Properties of Popped Finger Millet (Eleusine coracana) and its Application in Product Development Koros, Clarice Jepchirchir Finger millet (Eleusine coracana) is a highly nutritious grain with significant health benefits; however, its traditional processing methods have not been fully optimized for modern applications to enhance commercialization. This study evaluated the physicochemical, nutritional, and functional properties of popped finger millet and its application in cereal bar development. Finger millet grains were sourced from Jamhuri Market in Thika Town. The grains were sorted, cleaned, and dried, with an initial moisture content of 10.01%. The moisture content was subsequently adjusted to 15%, 18%, and 21% (in triplicates) and popped at chamber pressures of 120, 140, and 160 psi. The popped grains were analyzed for selected physicochemical, nutritional, functional, and microstructural properties. Grains popped at 21% moisture content and 160 psi were used to formulate five cereal bar variants with varying concentrations of guar gum and honey, which were then subjected to sensory, physicochemical, and microbiological analyses. Results indicated that increasing moisture content and pressure significantly (p≤0.05) enhanced popping yield and expansion ratio while reducing bulk density. The interaction between pressure and moisture content also had a significant (p≤0.05) effect on these parameters. Increasing moisture content from 15% to 21% significantly (p≤0.05) increased lightness and total color difference, while redness and browning index decreased significantly with increasing moisture content and pressure. Crude fat and moisture content of the popped grains decreased significantly (p≤0.05) with increasing pressure and moisture, whereas crude protein content increased significantly with pressure. Mineral analysis showed significant (p≤0.05) increases in zinc and iron content with increasing pressure and moisture levels. Total phenolic content also increased significantly, while phytates and tannins decreased significantly (p≤0.05), indicating improved nutritional quality. Functional properties were significantly influenced by processing conditions, with water absorption capacity, swelling power, and viscosities increasing, while bulk density decreased when popping pressure and moisture content were raised. Particle size distribution was also significantly affected by pressure, moisture, and their interaction. For the developed cereal bars, color attributes (lightness, redness, yellowness, and hue angle) varied significantly (p≤0.05), with increased lightness and yellowness observed at higher honey levels (10%–50%). Water activity ranged from 0.391 to 0.776 and decreased with increasing honey concentration, remaining within safe microbial limits. Bulk density and texture decreased significantly (p≤0.05) with increasing honey levels, improving handling and packaging characteristics. Proximate composition showed moisture content ranging from 3.47% to 11.35%, crude fiber from 2.31% to 2.70%, crude protein from 7.17% to 8.39%, and carbohydrates from 70.02% to 78.24%, all significantly influenced by formulation. Microbial analysis of the developed cereal bars revealed total viable counts ranging from 2.2007 to 2.7253 log CFU/g, within acceptable limits for ready-to-eat foods. No coliforms were detected, indicating satisfactory hygienic practices. Staphylococcus aureus was detected in two cereal bars, although no immediate health risk was indicated, while yeast and mold counts remained within acceptable limits. Sensory evaluation showed significant differences (p≤0.05) in appearance, flavor, taste, texture, and overall acceptability. Samples B1 and B5 were the most preferred, with overall acceptability scores above 7.0. Honey and guar gum significantly influenced sensory attributes,  xiv with higher honey levels enhancing flavor and consumer acceptance. In conclusion, popping pressure and moisture content significantly affect the nutritional, functional, and physicochemical properties of finger millet and demonstrates strong potential for value addition. The developed cereal bars exhibited acceptable sensory and microbial quality, supporting their potential as nutritious snack products. These findings highlight the role of popped finger millet in enhancing food and nutrition security and promoting the utilization of this underutilized indigenous crop. MSc in Food Science and Technology 2026-08-06T00:00:00Z