PHD-Department of Plant and Microbial Sciences
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Item Application of Taxonomic and Dna Barcoding Techniques in Identifying Commonly Traded Herbal Plant Species in Selected Counties, Kenya(Kenyatta University, 2022) Mwaura, Ann; Joseph Kamau; Omwoyo Ombori; Barbara GravendeelOver eighty percent of the world’s population depends on herbal products for their basic health care needs. However, this widespread popularity is counterbalanced with the lack of relevant research to authenticate the source and purity of the traditional herbal products. There exists an extensive history on use of herbal products but lately there are concerns on authenticity and safety of these products. The objectives of the study were: determine plant species commonly traded as herbal products, assess the products using taxonomic and DNA barcoding techniques, application of DNA barcoding technology in reference barcodes generation, and determine if the plant herbal products are accurately labeled. The study was carried out in selected markets in three counties in Kenya (Kajiado, Narok and Nairobi). Data collection involved use of structured questionnaires, species observation, taxonomic and DNA barcoding techniques. Structured questionnaires were administered to individual herbalists and complementary interviews with key herbalists to enrich the data collected. The local and common names were recorded and later translated to scientific names using para-taxonomists and previously published data. Scientific names listed on labels of packaged plants products were as well recorded. The generated species list guided the collection of voucher specimens and creation of a reference library of DNA barcodes. DNA barcoding technology was used to authenticate the herbal product samples. The common single species samples were analyzed using Internal Transcribed Spacer (ITS) and ribulose -1,5-bisphosphate carboxylase Large subunit (rbcL) DNA barcoding markers while metabarcoding was applied in multi-species samples using nrITS2 marker. The study revealed that 86 plant species belonging to 43 families were traded as herbal products in the regions. Most of these plants were shrubs (66 %) traded as stem and bark. Majority of herbal plant species belong to Fabaceae, Apocynaceae and Rhamnaceae families. The DNA technology successfully generated barcode sequences that were used as reference for herbal products identification. Single species samples were found to be more authentic compared to the mixed species samples as most species were identified to species level as listed on the label. Adulteration in single species samples was mainly by substitution with closely related and/or looks alike species, which raises concern on value and quality of the herbal products sold in the studied counties. Kajiado County had more authentic samples in comparison to Narok and Nairobi. DNA metabarcoding technology was successful in identification of mixed species sample at 92 % to species level and 4 % each to genus and family level. This study has made the first attempt to identify herbal plant species traded in selected markets in Kenya using DNA barcoding technology in combination with morphological and literature methods. Authentication using DNAbarcoding provided a more reliable and accurate results compared to morphological identification. DNA barcoding should therefore be applied in identification and verification of herbal products. DNA barcodes successfully generated and deposited in National Centre for Biotechnology Information (NCBI) Genbank form crucial reference data for future studies and can be used as a baseline library for useful medicinal plants of Kenya.Item Bioecology and population dynamics of red spider mites( a cari: tetranychidae) on tomato in small scale production systems in Kenya(2012-01-03) Sarr, IbrahimaTomato, Lycopersicon esculentum Mill. (Solanaceae) is one of the most important vegetables grown in Eastern and South Africa for local consumption and income generation by small scale farmers. Yet, yields of the crop are far below the potentials due to many factors including damage caused by red spider mites. This is aggravated by unsustainable control strategies relaying solely on highly toxic pesticides with long term harvest intervals and subsequent contamination of human and the environment. Sustainable and environmentally friendly integrated production and pest management approaches are therefore urgently required. This study aimed at providing basic information on the bioecology and the population dynamics of red spider mite, Tetranychus evansi pritchard and Baker and the two spotted red Spider mite, Tetranychus urticae Koch appeared to form the acarine complex in field tomatoes in Kenya. In laboratory life table studies, T. evansi, the most damaging red spider mite on tomatoes showed a high potential of increase at 30°c with a short overall developmental time from egg-to-adult of 8.82±0.21 days, a more female biased sex ratio of 1.75 female per male despite a low hatchability of the eggs. None of the female deutonymphs emerged at 100°c and a significantly slower overall developmental time from egg-to-adult of 55.13±2.83 days at 15°C (p<0.05) was recorded. The lower thermal developmental threshold for T. evansi was 12°C. The spatio-temporal and within plant distribution patterns of the two spotted red spider mite, T.urticae revealed the lower tomato canopy layer as the preferred zone for these spider mites. Furthermore, T. urticae was a very aggregative species. The preliminary sampling plan derived from this aggregative distribution patterns showed that a precision of 0.25 ( a ration of mean to standard error) was reasonable and still adequate for the density estimate of T.urticae adults in field tomatoes. The study carried out on the effect of the predators on T. Evansi, showed that five species of predators were associated with T. Evansi,and included; Phytoseiuhus persimilis Athias -Henriot (A cari: Phytoseiidae), Pronematus spp. (A cari: Tydeidae), Oligota spp. (Coleoptera: Staphylinidae) and Stethorus spp. (Coleoptera: Coccinellidae) However, these predators did not seem to have any impact on the population of T. evansi. An intensive regression analysis and a graphical description carried out between the T. urticae rate of increase, the plant quality, the predators and the weather data from three tomato growing seasons revealed that, the plant quality was positively associated with the rate of increase, while rainfall and temperature relative humidity interaction showed a negative relationship with the rate of increase. Further more, the stepwise regression between the rate of increase, the plant quality, the predators and the weather data showed that 40% of the variation in red spider mite numbers over the three growing seasons was explained by the biotic factors and weather condition. The population dynamics was a function of the initial level of infestion and the rate of increaseItem Carbon budget and sustainable harvesting of cyperus papyrus L. (Papyrus) in a papyrus swamp in lake Naivasha, Kenya(2012-02-14) Kariuki, Francis WachiraCarbon budget and sustainable harvesting of Cyperus papyrus (papyrus) in a papyrus swamp in Lake Naivasha were investigated. Carbon dioxide fluxes and photosynthesis were measured using eddy covariance and IRGA techniques respectively. Sustainable harvesting was assessed using five treatments, control, harvesting at intervals of 6, 12, 24 and 36 months each replicated five times in a Latin Square Design Carbon sequestration in the swamp was investigated through decomposition using litterbag and analysis of swamp components for carbon and nitrogen. Light compensation point was reached at PAR value of 1200 m-2s-1 between 08.00 and 09-00 hours. Mean maximum midday CO2 uptake was -24.40 ± 1.36 mol m-2s-1 corresponding peak PAR (1882 mol m-2s-1) with -31.19 and -18.92 mol m-2s-1 as the highest and the lowest uptake values respectively for days with monomodal peaks. On those days with bimodal peaks, the initial peak was -24.87 ± 9.29 mol m-2s-1 between 11.00 and 12.00 hours and a second peak at about 14.00 hours of -29.29 ± 1.27 mmol m-2s-1. Mean CO2 efflux was 10.28 ± 1.38 mol m-2s-1. Mean water vapour flux were 0.00 and 8.25 mmol ± 1.27 mmol m2s-1 for night and day respectively. The day peak corresponded to peak PAR, temperature and sensible heat. Papyrus had a maximum assimilation rate of 68.7 umol m-2s-1 and Carboxylation Efficiency (CE) of 0.06 compared to assimilation rate of 36.7 umol m-2s-1 and CE of 0.02 in Cyperus immensus. However, C. papyrus was CO2 saturated at a lower internal carbon dioxide concentration that C. immensus (C4), an indication of intermediate characteristics. Papyrus above ground biomass and culm density at 6 months harvesting interval showed significant (P<0.05) difference in terms of harvesting intervals. The overall culm density for six months intervals was 7.78±1.33 initial, 11.66 ± 2.55 and 11.62 ± 5.94 during the second and third harvest intervals respectively. This insignificantly declined (P>0.05) TO 10.66 ± 2.89 when the fourth harvest was delayed by three months and declined significantly (P<0.05) further to 4.98 ± 1.65 on the fifth harvest. The 12 months intervals showed the overall density increasing insignificantly (P>0.05) from initial 6.04 ± 2.35 to 9.36 ±2.46 at the second harvest. This declined significantly (P<0.05) to 7.42± 2.04 at the time of the third harvest. The above ground biomass showed an initial significant (P<0.05) decreased to 1087.64 ± 695.10 from 3290.52 ± 637.04 and thereafter significantly (P<0.05) increased to 1773.18 ± 496.27 gm-2 upon the third harvest. This was an indication that papyrus biomass was not density dependent. With the 24 months interval, the overall density showed a fairly stable state with density of 10.07 ± 1.99 and 11.18 ±1.73 culms m-2 initial and second harvests respectively. The results show that the rate of recruitment was approximately equal to that of mortality indicating a stable community. The above ground biomass significantly (P<0.05) increased from initial 2697.61±597.60 ±818.89 gm-2 a 25% increase. Decomposition was found to vary with the position (habitat) of litter at the site. The percentage material remaining after 300 days of decomposition was 74.05, 73.76 and 86.54 under the detritus, in water and on the detritus respectively. The decomposition rates after 90 days were 0.36, 0.81 and 1.02 and, the half-life were 3.94, 1.87 and 1.94 on the detritus, in water and under the detritus respectively. Analysis of papyrus plant organs and swamp components showed that percentage carbon was highest 47.92 ± 0.25 in the umbels and lowest 43.86 ± 0.63 in roots. Percentage carbon was 44.29± 0.18 in culms, and 47.08 ± 0.15 in rhizomes. Detritus and peat had percentage carbon of 37.95 ± 2.30 and 18.23 ± 0.23 respectively. Percentage nitrogen content was least 0.329 ± 0.02 and highest 1.297 ± 0.04 in the roots. Culms had 0.934 ± 0.04 while rhizomes had 1.219 ± 0.06% nitrogen content. The whole plant had 45.85± 1.92 and 1.14 ± 0.15% carbon and nitrogen contents respectively and C: N ration of 40:1. In detritus and peat, percentage nitrogen contents were 1.84 ± 0.14 and 0.977 ± 0.08 respectively. In terms of C:N ratio, the highest among the plant organs was 134:1 in senescent culms and least 34:1 in roots and 39:1 and 43:1 in rhizomes and umblels respectively and, 47:1 in culms. It was 19:1 and 21:1 in peat and detritus. This shows that the C:N ratio for papyrus organs was significantly (P<0.05) higher than the 17:1 dietary requirement of proteins for most animals. Carbon exchange indicates that papyrus swamps are presently sources of carbon. This status can be reversed through sustainable harvesting, which in the short term will be a source of carbon but will reverse once the amount of detritus is substantially reduced. Sustainable harvesting was found to be possible at 24 months intervals.Item Characterisation of Colletotrichum Gloeosporioides and Effectiveness of Management Strategies of Anthracnose Disease of Avocado in Murang’a County, Kenya(Kenyatta University, 2018) Kimaru, Stanley KirugoAvocado (Persea americana Mill) is a fruit commercially grown worldwide. Its production is affected by anthracnose disease which causes huge loss of avocado fruits both at farm level and in storage. Management of anthracnose disease worldwide has been mainly through use of fungicides. In Kenya, farmers use fungicides such as bayleton, milraz and Copper oxychloride which are not registered for controlling anthracnose in avocado. Despite this, the disease has continued to cause significant fruit losses of up to 40% as a post-harvest disease. This study was conducted to evaluate avocado production and anthracnose disease management practice; determine the incidences of anthracnose disease in avocado in Murang‘a County; determine the morphological and genetic characteristics of the Colletotrichum gloeosporioides; determine the pathogenicity of the representative isolates of the fungus on avocado varieties (Fuerte and Hass) and determine the inhibitory effect of selected fungicides on C. gloeosporioides isolates in vitro. A completely randomized block design was used in the laboratory tests while questionnaires were used during surveillance. The data on incidence, latent and surveillance was analysed descriptively into histograms and percentages using IBM SPSS version 21 software. Cultural and morphological data was analysed through ANOVA and Fisher's LSD to compare means using Genstart version 6 while molecular data was analyzed through PCR, sequencing (sanger sequencing), alignment (Bio edit software version 7.2.1 and phylogentics relationship of sequences using MEGA 7.0.18. Surveillance on anthracnose disease incidence and the control strategies adopted by farmers was done in the three agro-ecological zones upper midland (UM) 2, 3 and 4 where avocado is grown. The survey revealed that agro- ecological zone 2 had the highest disease incidence of 24.3% followed by zone 3 with 15% and lastly zone 4 with 9.6%. Farmers controlled the disease by pruning, sanitation and use of fungicides not registered for use in avocado. Eight percent of the farmers used fungicides while 30.2% used pruning strategy. Morphological and molecular studies identified C. gloeosporioides, C. boninense and Pestalotiopsis microspora as the causal agents of anthracnose. Further studies on C. gloeosporiodes showed a signicant difference (P≤0.05) among isolates in mycelia diameter and size of conidia. Both Hass and Fuerte fruit varieties were susceptible to all C. gloeosporioides isolates. Diameter of lesions on unripe Fuerte varieties four days after inoculation were not significantly different (P≥ 0.05) ranged from 7.33 -10.00 cm while in unripe Hass it was 6.33-7.33cm. However, lesions on ripe, Fuerte variety 2 days after inoculation ranged 10-17cm while ripe Hass was 9.67cm - 12.33cm. Hass variety was more tolerant to the disease as compared to Fuerte variety. The fungicides Bayleton, Milraz and Copper oxychloride significantly (P≤0.05) inhibited mycelial growth and sporulation of C. gloeosporioides invitro. Farmers should be encouraged to use cultural methods and field sanitation as management strategies to reduce loses and should be trained on strategies in handling, harvesting and storage. They should also be encouraged to grow Hass variety which is tolerant to anthracnose as compared to Fuerte variety. Field studies on the effectiveness of fungicides Bayleton, Milraz and copper oxychloride on anthracnose disease of avocado is recommendedItem Cross-stage physiological effects of the desert locust, schistocerca gregaria, aggregation pheromones on their behaviour and susceptibility to control agents(2012-03-07) Kane, Mohamed HabibThe desert locust, Schistocerca gregaria (Forskal, 1775) (Orthoptera: Acrididae) is a voracious and polyphagous pest of worldwide importance. Locust control relies on repetitive application of insecticides, rendering this option expensive and environmentally-damaging. New locust control initiatives emphasise the use of botanicals, entomopathogens, Insect Growth Regulators (IGRs), and pheromones. Phenylacetonitrile (PAN), the major and key component of the aggregation pheromone of older male adult desert locusts showed deleterious effects on conspecific nymphs. The nymphal pheromone blend (NPB) de-aggregated conspecific adults and lead gravid females to disperse their eggpods. However, the optimum use of PAN and NPB on desert locust control has not been investigated yet. The aim of this study was to optimise the use of PAN in enhancing susceptibility of S. gregaria nymphs to fenitrothion and neem oil and assess the effects of nymphal pheromone blend (NPB) on conspecific adults. The whole work was carried out under laboratory conditions. The results showed that desert locust nymphs were sensitive to all carriers that were tested [Tween 20, paraffin oil, polyethylene glycol 200 (PEG 200), paraffin oil, cyclohexanone], either applied topically or in vapour form regardless of the monitored parameters including food uptake, grouping behaviour and walking behaviour. Comparison of two modes of application of PAN showed that the release of PAN from a vial with a vent of 2 mm on its cap was significantly more effective in reducing the food uptake compared to their respective controls than its release from impregnated cotton roll. However, in both cases, the effect of PAN on the food uptake of test nymphs was dose-dependent. The optimum release rate of PAN (3.9 ± 0.14 mg / day) significantly reduced the grouping behaviour of treated nymphs compared to the controls throughout the experiment. It also reduced the food uptake and the total haemocyte count of treated nymphs compared to the controls. Of the haemocyte groups, the coagulocytes were the most affected by PAN. The NPB affected the haemocyte population of three and 15 day-old adults and gravid females. The NPB significantly increased the total haemocyte count (THC) of treated, three day-old adults and gravid females, but marginally decreased the THC of 15 days-old locusts. The increase of the numbers of plasmatocytes in the haemolymph of NPB-treated insects compared to the controls was significant in both three day-old adults and gravid females. Gregarious female locusts treated with NPB significantly dispersed their egg pods (75%) similar to the solitarious insects (81.25%). Only 25 and 37.5 % of the controls and carrier-treated females, respectively, dispersed their egg-pods. PAN enhanced mortality caused by sub-lethal doses of fenitrothion (1.19 x 10-2, and 1.79 x 10-2 mg a.i / nymph), and the lowest recommended dose of the pesticide (2.38 x 10-2 mg a.i / nymph) in third and fifth instar nymphs. This was significant on fifth instar nymphs for all three doses of fenitrothion applied three and five days after the start of PAN treatment. Similar mortality rates on fifth instar nymphs were obtained with 75% and 100% of the recommended dose of fenitrothion, when both doses of the pesticide were combined with the higher dose of PAN (3.9 ± 0.14 mg / day). Also, the results showed that at 75% of recommended dose of fenitrothion the two releases rate of PAN (3.9 ± 0.14 and 0.93 ± 0.06 mg / day) enhanced the mortality caused by fenitrothion to similar levels (66.16 and 66.19%, respectively). The best combination of both products was the application of 75% of recommended dose of fenitrothion three days after start of exposure to the lowest dose of PAN on to the nymphs. PAN also enhanced the efficacy of fenitrothion on third instar nymphs, but to a lesser extent than on fifth instar. In fifth instar nymphs, the combination of PAN and fenitrothion killed up to 4.34 times nymphs more than fenitrothion alone. This ratio was less by 1.2 times in third instar nymphs. The youngest three-day-old nymphs were significantly more susceptible to fenitrothion alone than the six or eight day-old nymphs in both third and fifth instar nymphs. PAN enhanced the mortality rate and induced growth disruptive effects characterized by delay of the moult and malformation of fledgelings. The overall mortality in all experiments was less than 50%. The malformations affected mostly the wings, hind legs, and the antennae, affecting either one, two or three organs or all three in different insects. The best combination in this study with regard to all parameters monitored (mortality and mal-growth) is that of PAN and the medium and sub-lethal dose of neem oil (39.72 x 10-5 mg a.i / nymph) applied on the same day.Item Cultural management of banana weevil cosmopolites sordidus germar (coleoptera: curculionidae) for improved banana field in Western Kenya(2012-04-04) Ngode, LucasStudies on the effects of planting materials, weevil trapping, and intercropping on the banana weevil cosmopolites sordidus Germar. and crop yields were conducted in western Kenya from 1994 to 1997. The objectives of the investigations were to explore the efficacy of non-pesticidal options for the management of the banana weevil. Field experiments were undertaken using clean planting materials, pseudostum traps for the weevil management and intercropping banana with groundnuts Arachis hypogaea L. different banana plant densities. Results indicate that paring and hot water treatment is effective in cleaning infested banana planting material. It did not affect the banana growth and yield performance. The infested planting material resulted into significantly high weevil damage and yield losses within two crop cycles compared to the infested but pared and hot water treated material. The lowest damage of 12.6% was recorded under furadan protection while the highest damage of 66% was in the infested suckers. The infested, pared and hot water treated material suffered 17.6% damage while in the healthy material it was 16.3% during the three crop cycles. The banana bunch yield under insecticide protection was 14.5 kg and in the healthy plant it was 15.3 kg whereas the infested, pared and hot water treated material yielded 13.3 kg. These weights were not significantly different from each other but differed significantly different from each other but differed significantly from the infested materials yield of 6.8 kg. The associated yield losses were 53.1% in the infested materials, 16.6% under paring and hot water treatment and 8.3% under insecticide protection. The use of split pseudostem traps for weevil management at low weevil population density significantly reduces the number of adult weevils and larval damage caused. However, trapping where the infestation and resulting damage is already high may not result into significant population decrease and yield responses. Intercropping banana with groundnut did not affect weevil colonizing the banana but influenced their distribution during the early stage of the banana establishment. The banana crop planted at 3x3m and 5x5m spacing did not affect the growth of the groundnut during the first one year. Thereafter, the banana canopy significantly reduced the growth and yield of the groundnuts in the 3x3x banana spacing. Nevertheless, spacing significantly influenced the banana yield per unit area with the 3x3m banana spacing yielding more than double that of the 5x5m spacing. The number of flower thrips and aphids were reduced in the banana intercrop compared to those in the groundnut monocrop. Incorporation of organic mature improves the banana performance. Nevertheless, with increased bunch weight snapping of the banana became significant due to the weakened corms. Thus, the use of clean planting materials, weevil trapping and application of organic manure are essential components of banana weevil integrated management.Item Distribution, Behavioural Biology, Rearing and Pollination Efficiency of Five Stingless Bee Species (Apidae: Meliponinae) in Kakamega Forest, Kenya.(2013-08-01) Kiatoko, NkobaThe study on distribution, behavioral biology, rearing and pollination efficiency of five stingless bee species (Apidae: Meliponinae) in Kakamega forest, Kenya showed that; species diversity was higher at Ivihiga compared to Isiekuti sites. Within habitats, species diversity varied and the indigenous and the mixed indigenous forests had more species diversity than the other habitats. The number of nesting habitats and also the chance of getting a nest of a particular species within nesting habitats varied among the stingless bee species. The nest pattern was under-dispersed for almost all the species nesting in the indigenous forest; mixed indigenous forest and grassland with the indigenous tree species. The nesting pattern for M. ferruginea (reddish brown) and H. gribodoi changed from an under-dispersed and over-dispersed pattern, respectively, to a clumped nest pattern when nesting in the homesteads. Within interspecific species nesting in the same habitat and within the nesting habitats of conspecific species; a difference was observed in the average nearest neighbour distance separating their nest entrances. Three different nesting sites were identified overall species (tree, underground, residential houses). Nest aggregation was observed within four bee species (except M. lendliana) and the average less minimum nearest neighbour distance between nests aggregated on a single substrate varied within conspecific and interspecific aggregation. Daily temperature and humidity influenced the bee flight activities out for foraging or grooming; with temperatures below 22oC and relative humidity above 70% being not ideal for the five bee species to start or maintain their out going flight activity. M. ferruginea (reddish brown) and H. gribodoi were the only species which bite to defend their nests from intruders. M. ferruginea (reddish brown) and M. lendliana were the only species which completely seal the open entrance of their nests at night. Acceptance of the designed hive types varied across bee species. All types of hives designed for M. ferruginea (reddish brown) were accepted at a probability of 0.63 and above. M. ferruginea (black) showed preferences for the two non compartmented hive designs and OATH hive type at a probability of 0,63 and above. H. gribodoi accepted only the icipe 1 hive model compared to the two designs of compartmented hives. M. lendliana preferred nesting only in the hives made out of clay as opposed to wooden hives. Three colonies of M. bocandei were succefully reared in the icipe 1M hive design. The average annual honey production under domestication varied among the five bee species and was higher in the M. bocandei species (3.13 ± 0.21 litres). The hive splitting method was more successful in propagation of colonies of three Meliponula species. Natural enemies recorded in this study included mainly parasites, predators and disturbers. Lastly, flowers of green pepper pollinated by H. gribodoi produced heavier fruits with superior number of seeds and the seeds were bigger compared to those produced by self-pollinated flowers or flowers pollinated by feral insects.Item Diversity and Molecular Phylogenetic Analyses of Parmelioid Lichens (Parmeliaceae, Ascomycota) In Kenya(Kenyatta University, 2017-11) Muigai, Kirika PaulLichens are symbiotic associations of fungi and algae or cyanobacteria.They are ecologically important as bioindicators for air pollution, forest age and health, and as sources of food, shelter and nesting materials for animals. Man has historically used them for dyes, medicines, poisons and in the manufacture of perfumes and antibiotics. Globally there are an estimated 28,000 species of lichens. Parmeliaceae is the largest family with over 2800 species in about 80 genera. Parmelioid clade is the largest group comprising 75% of the total number of species in the family. About 180 species of parmelioid lichens distributed in 19 genera are known for Kenya. The advent of molecular tools has shown that, the morphological and chemical characters traditionally used to delimit taxa in lichens underestimate diversity. Application of molecular data has therefore become a prerequisite while making taxonomic evaluations in this group. Molecular DNA sequence data were used to evaluate the phylogenetic relationships and to re-asses traditional phenotype-based taxon delimitation in Bulborrhizina, Bulbothrix, Canoparmelia, Hypotrachyna, Parmelinella, Relicina and Relicinopsis. Seventy seven samples were collected from 5 floral regions in Kenya and duplicates deposited in EA, F and MAF herbaria. Genomic DNA were extracted from newly collected samples and the ITS, nuLSU and mtSSU regions of rDNA sequenced using Sanger sequencing approach. To infer phylogenetic relationships, 6 datasets of concatenated ITS, nuLSU and mtSSU comprising 746 DNA sequences were analyzed using ML and BI methods. Three species, Bulbothrix kenyana, Hypotrachyna himalayana and Parmelinella schimperiana were described as new to science, and taxonomic re-evaluation of 22 taxa carried out. Eight new combinations were proposed: Bulbothrix sublaevigatoides, Parmotrema epileucum, P. zimbabwense, Relicina dahlii, R. intertexta, R. malaccensis, R. rahengensis and R. stevensiae. The monotypic genus Bulborrhizina had not been studied previously using molecular data and its phylogenetic position hitherto unknown. DNA sequences of Bulborrhizina africana were analyzed with 95 other samples of parmelioid lichens. In the resultant phylogenetic tree, B. africana clustered with Bulbothrix, in the Parmelina clade. Species boundaries in Bulbothrix isidiza and B. tabacina, two pantropical and asexually reproducing species were re-examined using mutilocus dataset of Bulbothrix specimens from E. Africa, Asia and S. America. Five species-level lineages in Bulbothrix isidiza s.lat. and three in B. tabacina s.lat were recovered. Alternative hypothesis testing using SH and ELW tests significantly rejected monophyly of B. isidiza and B. tabacina, respectively. In the phylogenetic analysis of Canoparmelia s.lat. the genus was recovered as polyphyletic with three divergent lineages, two formed a sister group relationship with Parmotrema. Consequently they were included in Parmotrema and recognized at subgeneric level as Parmotrema subgenus Africanae and Crespoa, the former described as new. Genetic diversity of the pantropical sorediate species Hypotrachyna sorocheila was assessed with the resultant phylogeny forming two distinct species-level lineages.The pantropical species Parmelinella wallichiana s.lat. was assessed, samples of P. wallichiana were recovered in four well-supported clades. Evolutionary relationships of Relicina and Relicinopsis were elucidated; Relicina was recovered nested with Relicinopsis. However, based on differences in conidia, Relicinopsis is accepted at a subgenus rank as Relicina subgen. Relicinopsis. The use of DNA sequence data in understanding true diversity and biogeography in Parmeliaceae is underscored. A wider taxon sampling is recommended for the lineages that remain undescribed in this study.Item Efficacy of Selected Medicinal Plants Used by the Ogiek Communities against Microbial related Infections(2014-02-24) Amuka, Omari; Okemo, P. O.; Mbugua, P. K.Ethnobotany and traditional medicines have been used for bioprospection for modern pharmaceutical in all the world continents. In Kenya the ethnobotanical of several communities has revealed that plants are important source of medicinal products that require further research to establish their validity, efficacy and quality of health services. The Ogiek communities who currently live in harmony with nature and have minimal with modern cultural practices exhibit high potentials for discovery of new pharmaceutical products through ethnobotanical, phytochemical, and microbial strategic studies. Furthermore, such studies have been necessited by newly emerging and reemerging diseases and the development of resistance of diseases to the drugs that are currently in use. The Ogiek community, who has lived in Mau forest for over six centuries, is fast being assimilated into other culturally stronger communities. However, their life is shrouded in secrecy and their rich cultural practices including ethnomedicine are being lost. Ethnobotanical field surveys revealed that over 80% of the Ogiek community has constructive knowledge of the forests and forest products. They have clear knowledge of medicine plants, their pharmaceutical procedures and pharmacological manifestations. It was evident that majority of the human health complaints were parasitic, bacterial, and fungal in nature. Symptomatic areas were the abdomen, chest, and the head. A total of 49 plant species in 33 families were collected. Bioassay of the extracts showed that some of the plant species possessed promising antimicrobial activities. In order to verify the efficacy of the drugs, selected pathogens were selected and in vitro studies carried out on individual crude extracts and essential oils. It emerged that 16 plant species showed reasonable biological activities on the selected human pathogens. Further studies to confirm the efficacies of the drugs were successfully done to establish the susceptibility (MIC, MBC and MFC) individually. Several metabolites known for their efficacy were identified. There is need to further document the Ogiek culture, in situ and ex-situ conservation of the Mau forest complex so as to conserve the biodiversity for the future generations. Further elucidation of the extracts may lead to discovery of new pharmaceutical compounds that could be used in the synthesis of new drugs for the currently challenging medical conditions.Item An ethnopharmacological investigation of plants used by Abagusii traditional medical practitioners(2012-03-07) Gisesa, Nyangate ObieroAn ethno-medical survey of plants used by Abagusii Traditional Medical Practitioners was carried out and 166 plant species representing 138 genera and 62 families were botanically identified. Antimicrobial and phytochemical screening of 20 plants selected from the survey, and reputed to be widely used in the treatment of infectious diseases, was carried out. The various plant parts (roots, stems, leaves and flowers) of one of the medicinal plants, Euphorbia hirta L. were Sohxlet extracted with three solvents in order of increasing polarity (ether, methanol and water). The solvent with the most active extracts (methanol) was used for subsequent extractions of the rest of the plants. The extracts were screened for bioactivity using the disc diffusion method. Using the same method representative organisms were screened to represent a broad spectrum of microorganisms including specific clinical isolates from Kenyatta National Hospital. Tests were performed using the selected plant extracts to find out how effective individual extracts were against specific human pathogens. The phytochemcal screening was done by the use of successive and selective extractions with solvents of different polarities (ether, methanol and water). The screening covered mainly nitrogenous compounds, acetogenins, polyketides, isoprenoids and carbohydrates. In the antimicrobial screening it was found that most of the plant extracts inhibited the growth of the 7 bacterial species, the fungus and the majority of the 13 pathogenic micro-organisms that they were tested against. In the phytochemical screening 12 plants (60%) gave a positive reaction for alkaloids, 14 plants (70%) tested positive for tannins, 12 plants (60%) tested positive for flavonoids, 17 plants (85%) tested positive for coumarins, 9 plants (45%) tested positive for polyketides(emodin), 7 plants (35%) showed the presence of anthocyanins, 7 plants (35%) tested positive for anthracene glycosides and 6 plants (30%) showed the presence of fatty acids, 17 plants (85%) showed the presence of steroids/triterpenoids, 13 plants (65%) tested positive for saponins, 17 plants (85%) tested positive for volatile oils and 10 plants (50%) showed the presence of carotenoids, 9 plants (45%) showed the presence of polyuronoids, 11 plants (55%) tested positive for polyoses while 2 plants (10%) showed a positive reaction to starch.and 18 plants (90%) tested positive for reducing compounds. The results show that the local flora has a diversity of plant species with potential medicinal value. The results also confirm that there is credence to a number of uses to which herbalists put in certain plants and their use in traditional medicine and that the plants used by Abagusii Traditional Medical Practitioners are effective against pathogenic micro-organisms. The results supported the hypothesis that the plants used by the Abagusii Traditional medical practitioners have compounds of curative value and therefore they play an important role in the basic health care of these peopleItem Fungal parasitism of root-knot nematode eggs and effects of organic matter, selected agrochemicals and intercropping on the biological control of meloidogyne javanica on tomato(2012-06-05) Owino, P. O.Root-knot nematodes are serious pests all over the world. Over 50% Pyrethrum losses have been associated with these pests in Kenya. Chemical management of these organisms is effective but difficult to sustain for long-term benefits, and alternative control measures must be sought. The use of fungal antagonists may provide an alternative but factors affecting their efficacy are not known. Therefore, in vitro, in vivo and greenhouse tests were conducted at Kenyatta University, Nairobi, Kenya, to compare efficacy of the fungi Paecilomyces lilacinus Thom(sam), Fusarium oxysporum Schlecht isolates 1, 2 and 3, and Phoma herbarum against root-knot nematode eggs, egg masses and females, and (2) assess whether aldicarb (10% Temik), captafol (orthodifolatan 80% wp), organic matter and intercropping with the nematicidal plants Tagetes minuta L, Datura stramonium L,. and Ricinus commnis L., could stimulate , inhibit or have no effect on the biocontrol potential of P. lilacinus, tomato (Lycopersicon esculentum (Mill) shoot heights and weights, nematode population in soil, gall index and number of galls per gram root weight were assessed using standard methods. Gall index was based on a subjective scale of 0-4, where 0=no gall and 4=76 - 100% of the root system galled. To obtain the P. lilacinus isolate and other fungi for this study, 120 fungal isolates were isolated from nematode eggs extracted from soils collected from fields in Kakamega, Kiambu, Nyeri, Mombasa, Baringo, Kisumu, and Kisii districts. Isolates that parasitized 30-95% of eggs on agar were selected for further tests. Paecilomyces lilacinus and F. oxysporum isolate 1 parasitized significantly (P<0.05) more M. javanica eggs and females on agar than F. oxysporum isolates 2 and 3, and P. herbarum,. P. lilacinus F. oxysporum isolates 1,2 and 3, and P. herbarum parasitized up to 91.9% eggs and 87.3% females, 82.4% eggs and 79.1% females, 25.9% eggs and 44.7% females 9.4% eggs and 19.2% females and 29.5% eggs and 60.6% females, respectively, on water agar. Levels of egg parasitism, however, were lower in sterile field soil. P. lilacinus and F. oxysporum isolate 1, the most aggressive isolates on agar, parasitized only 22.2% and 19.6% of the eggs in sterile soil, respectively. Besides egg parasitism, the five fungi influenced egg hatch differently. Up to 22.2%, 24%, 24.1%, 55.8%, and 74.4% of egg hatched on WA plates inoculated with F. oxysporum isolate 1, P. lilacinus, P. herbarum, F. oxysporum isolate 2, and F. oxysporum isolate 3, respectively. Chicken manure, and the nematicidal plants T. minuta, D. stramonium and R. communis significantly increased egg parasitism by up to 112, 72, 54.9 and 106.3% respectively, when compared to controls. The nematicidal plants also stimulated parasitism of M. javanica eggs were parasitized in soils planted with R communis T. minuta and D. stramonium, respectively 50 days after inoculation, compared to 23.2% in controls. Levels of egg parasitism were however, lower, 17.6, 16.4 and 15.1% respectively, 98 days after inoculation compared to 10.3% in controls. In both cases, percentages of egg parasitism were higher than those obtained in non-amended soils, but lower than those obtained on water agar. R. communis, T. minuta and D. stramonium increased egg parasitism by 3.2, 28.4 and 22% respectively, 50 days after noculation. The treatments, chicken manure, R. communis, D. stramonium and T. minuta also suppressed nematode population and gall development significantly than controls. Galling indices were decreased by up to 76.5%, 35.3, 47% where chicken manure, R. communis, D. stramonium and T. minuta were used, respectively. These treatments enhanced shoot weights by up to 159, 106, 100, and 64.7% respectively when used in combination with P. lilacinus. Delaying the time of planting tomato in soil amended with chicken manure and infested with P. lilacinus from 0 to 8 weeks increased egg parasitism significantly (b=1.9;) and significantly reduced gall development (b=-0.5; r=-0.9). Tomatoes planted in chicken manure-amended soil 8 weeks after incorporation of chicken manure and P. lilacinus were significantly heavier than those planted 0 - 6 weeks after soil amendment. The number of juveniles increased with time of planting in soil not amended with chicken manure (b=+2.1; r=0.44) but the increase was not significant. Significant decrease in galling index with time of planting (r=-0.95) was observed in pots treated chicken manure alone or in combination with P. lilacinus. In general, aldicarb and chicken manure were effective in suppressing gall development and nematode population build up, whether used alone or in combination with P. lilacinus. Among the nematicidal plants, R. communis enhanced egg parasitism more significantly than T. minuta or D. stramonium. However, the maximum levels of egg parasitism achieved in all tests were less than 40%, an indication that the treatments used may not enhance egg parasitism to levels that can reduce nematode populations significantly in the field.Item Genetic transformation of select African sweet potato (ipomoea halalas l. Lain.)Cultivars with Weevil resistance genes and evaluation of phytoalexin levels from infected roots(Kenyatta University, 2015) Wamalwa, Lydia NanjalaAbstract Sweetpotato is an important root and tuber crop in Sub-Saharan Africa (SSA) used as food and feed but weevil infestation remains a major concern. Weevils account for production losses between 28 and 100% but no resistance genes are available in the natural gene pool. When weevils attack, they create avenues for secondary infection, which in turn elicit phytoalexin production, toxic to farm animals. Since genetic transformation has been widely used to introduce genes into germplasm that may not be available in the natural gene pool, it was used in this study. Objectives of this study included (i) to develop a regeneration protocol of 32 SSA cultivars through indirect organogenesis, (ii) to develop a transformation protocol for the best cultivars using uidA gene and the double gene construct (cry7AaJ and ET33-34), and (iii) to isolate a fungus that infects sweetpotato after weevil infestation and subsequent analysis of the furanoterpenoid elicited from infected roots. Regeneration and transformation were conducted via indirect organogenesis. Four gene constructs were used in this study: pCIPlOO, pCIP87, pCIP88 and pCIP85. Phytoalexin levels were evaluated on four consumer-preferred sweetpotato cultivars using coupled gas chromatography mass spectrophotometry (GC-MS), thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and Nuclear Magnetic Resonance (NMR). Results showed 6 SSA cultivars with RE above 40% while TE of 5 SSA cultivars revealed GUS-stained calli between 6 and 98%. Six transgenic events were produced using the double gene construct as confirmed by southern blot but they had low protein levels. For phytoalexins, levels between 0.3 and 2,900 mg/kg were recorded. The results suggested that pre-screening for high RE and TE was important in identification of the best cultivars. Low protein concentration levels obtained could be due to post transcription or/and post-translational factors. Such high variations in furanoterpenoid levels have previously been reported, and could be an indicator of a potential health concern to both animals and humans on consumption.Item Geographic variation in the development of cotesia sesamiae (hymenoptera: braconidae) on Busseola fusca (lepidoptera : noctuidae) in Kenya: polydnaviruses and co-evolutionary dynamics(2011-12-07) Gitau, Anne CatherineMicrogastrine endoparasitoids co-inject symbiotic viruses known as polyDNAviruses (PDV) together with other wasp factors such as the venom and calyx fluid proteins during oviposition in hosts. These factors disrupt the host immune system allowing the parasitoids to develop successfully. In Kenya, the endoparasitoid Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) exists as two biotypes that differ in their ability to parasitize the stem borer Busseola fusca (Lepidoptera: Noctuidae). Cotesia sesamiae from western Kenya completes development in B. fusca larvae hence it is virulent. The coastal C. sesamiae biotype does not complete development and eggs oviposited get encapsulated in B. fusca larvae, and therefore it is avirulent. It is not yet known if intermediate C. sesamiae populations exist between western and coastal Kenya. On the other hand, several B. fusca biotypes have been described recently and it is not clearly understood whether this host also contributes to variation in C. sesamiae parasitism. In this study, B. fusca acceptance and suitability of different strains of C. sesamiae were examined. The avirulent strains were reluctant to oviposit in B. fusca larvae while the virulent strain readily oviposited in this host. Egg loads of the virulent C. sesamiae from Kitale were significantly lower compared to those of the avirulent Mombasa and Taita C. sesamiae females. Development of C. sesamiae in B. fusca larvae was tested in an interaction matrix. Results showed that both C. sesamiae and B. fusca contributed to the variation in the parasitoids' success. 39% of the variation was attributed to the geographic locality of C. sesamiae, 35% by the host locality and 27% by their interaction. Geographic variation in successful parasitism of hosts by their parasitoids was attributed to the co-evolutionary dynamics and selection pressures in C. sesamiae local community. Results from this study showed that the avirulent C. sesamiae strains have been under selection pressure to evolve a system that suppresses B. fusca 's immune reaction. The CrV 1 gene homolog was tested on various C. sesamiae strains using Polymerase Chain reaction (PCR). The CrV 1 gene was present in all the C. sesamiae strains. However, restriction enzyme tests showed that the gene is differently organized in the virulent and the avirulent C. sesamiae strains. The CrV 1 gene expression was found in fat bodies and haemolymph tissues of B. fusca larvae using the Reverse Transcriptase-PCR (RTPCR). Results showed that this gene was expressed in the fat bodies and haemolymph tissues of B. fusca and S. calamistis parasitized by the virulent C. sesamiae strains. For the avirulent C. sesamiae strains, CrV 1 gene expression was only evident on the permissive host S. calamistis but not B. fusca tissues. Differences in calyx fluid contents of the virulent and avirulent C. sesamiae populations were evaluated using the 2D-gel electrophoresis and results showed that more protein spots were present in calyx fluid of the virulent C. sesamiae than that of the avirulent strain. Changes in protein profiles in B. fusca larvae parasitized by the two C. sesamiae strains was evaluated by SDS-PAGE gel on fat body and haemolymph tissues. Results showed parasitism-specific protein bands in both tissues parasitized by the two C. sesamiae strains.Item Indigenous knowledge and effects of integrated soil fertility management on growth, grain yield and rhizobia genetics of selected cowpea varieties(2011-08-15) Kimiti, Jacinta MaliaThe main objectives of this study were; (1) To find out whether farmers in Makueni District were aware of soil fertility status in their farms and annual food availability, (2) To find out the proportions of cultivated areas under grain legume production and the problems faced by farmers in grain legume production, (3) To screen and select high yielding cowpea varieties for dryland Makueni District, (4) To determine the effects of integrated soil fertility management (ISFM) on nodulation, growth and grain yield of selected cowpea varieties, and (5) To determine the effects of ISFM on nitrogen fixation, indigenous soil rhizobia populations and rhizobia diversity. Farmer participatory meetings were used to establish whether farmers recognized soil fertility as a problem in legume production. Results obtained revealed that farmers in the selected sites recognized soil fertility as a problem and included it in the list of general problems affecting them. Participating farmers indicated that only 2% of the cultivated farms in the study sites had fertile soils. To document grain yields, area under legume cultivation and problems faced by farmers in grain legume production, a structured questionnaire was used to collect information from farmers. Results obtained showed that grain yields ranged from 30 kg/ha to 416 kg/ha and area under legume cultivation from 48% to 92%. Problems faced by farmers in legume production included low soil fertility, inadequate farm inputs, weeds, pests and diseases. To select pioneer cowpea varieties, 34 cowpea varieties were selected and screened for two seasons at Kiboko Dryland Research Station. Some of the cowpea parameters assessed included pod length, plant biomass, grain yield and weights of 100 seeds. From the screening studies, nine cowpea varieties were selected for on-farm trials. To determine the effects of integrated soil fertility management (ISFM) on nodulation, growth and grain yield of selected cowpea varieties, on-farm trials were established at two sites. The nine cowpea varieties that had been selected during the screening studies were planted in the trials. Treatments applied included a control, farmyard manure at 2.5 t/ha, phosphorus as triple superphosphate (TSP) (P205, 0:46:0) at 15 kg/ha and a combination of both manure and TSP at the singly applied rates. Data collected included nodule and shoot biomass, and grain yields. Results obtained revealed that treatment application enhanced nodule and shoot biomass, and grain yields. Nitrogen fixation was estimated using 15N natural abundance method while rhizobia populations were determined using most probable number (MPN) experiment. Rhizobia diversity was determined using culture characterization and direct PCRRFLP of the 16S-23S rRNA intergenic spacer region (IGR) of rhizobia genome. Results of nitrogen fixation showed that 46-53% nitrogen (N) was fixed at a wetter site, while no N fixation took place at a drier site. Results from rhizobia population assessment revealed population counts of 4.89x102 to 2.0x104 cells/gram of soil with lower rhizobia counts at planting relative to the harvesting time while high rhizobia counts were recorded in amended soils relative to the controls. Further, restriction of eighteen rhizobia isolates from cowpea nodules with MspI restriction endonuclease revealed four rhizobia IGS groupsItem The influence of drip irrigation on ecophysiology and yield of arabica coffee hybrid Ruiru 11(2012-04-11) Gathaara, M. P. H.The influence of drip irrigation on Coffee arabica L. cultivar Ruiru 11 was studied in a field experiment. Drip irrigation was applied when a soil moisture deficit (SMD) of 100 mm was recorded. FOur drip irrigation rates (25, 50, 75 and 100 mm of water) were applied to offset the SMD by 25%, 75% and 100%. These were applied at intervals of 21, 28 and 42 days. The control treatment was unirrigated. Primary (first order) branch extension growth, stomatal conductance, CO2 assimilation, leaf water potential, biomass accumulation, root distribution, yield and quality were measured. The drip irrigated coffee plants had a significantly higher primary branch extension growth rate (8.1 mm wk-1), stomatal conductance (0.605 mol m-2 s-1) and leaf water potential at 14.00 h (-1.98 MPa) than the unirrigated plants. The corresponding growth rate, stomatal conductance and leaf water potential in the unirrigated plants were 1.2 mm wk-1, 0.368-mol m-2 s-1 and -2.67 MPa. Irrigated plants had higher CO2 assimilation rates in the upper levels of the plant canopy when compared to the unirrigated ones. Root distribution was not significantly influenced by irrigation. However the mean vertical distribution (125 cm) was about half the horizontal distribution (232 cm). The unirrigated coffee had a total coffee yield of 6142 kg per ha. The 25 mm, 50 mm, 75 mm and 100 mm irrigation rates resulted in yields of 9373 kg, 10531 kg, 10307 kg and 8726 kg per ha respectively. Theses represented increases of 52.6, 71.5, 67.8 and 42.1% respectively. The results showed that the 50 mm irrigation rate may be optimal. Evidence that dry season water requirements for the cultivar may be met by low irrigation rates at short intervals is presented. The practical implications of the results are discussed.Item Interaction between arbuscular mycorrhiza fungi (AMF) and meloidogyne hapla on pyrethrun in Kenya(2012-04-05) Wanjohi, Waceke J.In this study, mycorrhizal status of pyrethrum in Kenya was determined. Fungal isolates obtained from pyrethrum fields were screened for efficacy against M. hapla and in improving pyrethrum growth. Effect of inorganic P fertilizers and intercropping on Glomus sp. (isolate KS14), one of the effective isolate against M. halpa was dertermined. To determined mycorrhizal status of pyrethrum, spores were extracted from soil samples obtained from 30 different study sites and their abundance (numbers) and composition (types) determined. In addition, percent growing ecozones; Kisii, Limuru study and Molo representing low, mid and high altitude ecozones, respectively. In general, Limuru study sites revealed lower percentage of root colonization, higher spore were characterized and placed into various AMF genera. Except for Sclerocytis spp. five of the six known AMF genera were encountered in the study sites. Glomus was the most commonly encountered genus (10 isolates) followed by Acaulospora (5 isolates). Only one isolate of Entrophospora was present. In the screening tests, arbuscular mycorrhiza fungal (AMF) isolates; KS14 (Glomus sp.3); KS 18 (Glomus etunicatum), KS74 (Scutellospora sp.3), ML34 (Glomus sp.6), ML35 (Glomus sp.7, LM61(Glomus sp.4) and LM83 (Gigaspora sp.3) were screened . Fungal mixed inoculum (20g) was incorporated into sterized sand-soil mixture before planting with 6-week-old pyrethrum seedlings. The inoculum consisted of spores, hypla, infected root fragments and soils in which the plants for inoculum production were growing. The plants were inoculation with 6000 M. hapla second stage juvenile (J-2) 3 months after fungal inoculation. Dry shoot weights, fresh root weights, percent root colonization by the fungi, nematode gall indices, number of eggs, females and J-2 were determined at the end of the experiment 2 months after nematode inoculation. Root length was also determined where possible. Isolates KS14, LM61, KS18 and KS74 significantly improved top biomasses of fungus-treated and fungus-nematode-treated plants. Isolate KS14 was the most effective (47% top biomass increase) followed by isolates LM61 and KS18 (33%). Isolates ML34, ML35 and LM83 improved top biomasses of fungus-nematode-treated plants. Fungal isolates KS74 and ML34 significantly increased fresh root weights of pyrethrum by 45% and 50%, respectively. Isolate KS18 reduced pyrethrum by 45% and 50%, respectively. Isolate KS18 reduced pyrethrum root length by 18%. Except fungal isolates ML34 and ML35, all the other isolates suppressed M. hapla disease severity and egg production. Isolate LM61 (86%) was the most effective followed by KS14 (75%). Isolates KS18, KS74 and LM83 suppressed disease severity and egg production by up to 75%, 32% and 37%, respectively. All the fungal isolates screened significantly reduced the number of females in the root system and J-2 in the soil. The presence of nematodes in fungus-treated plants did not affect root colonization by the fungus except in KS18, ML34 and ML 35-treated plants. In testing for effects of inorganic P fertilizers on efficacy of KS14, Triple super phosphate (TSP) and Single super phosphate (SSP) were used. The fertilizers were applied at two rates (1 and 2g/g soil) at the time of fungus inoculation. Two months after, plants were inoculated with the nematodes. The plant growth and nematode disease parameters were determined at the end of the experiment, 2 months after nematode inoculation. The fertilizers at both levels improved plant growth of non-mycorrhized, mycorrhized, non-mycorrhized-nematode and of mycorrhized-nematode-treated plants. The fungus in general improved plant growth on its own or in the presence of nematodes but not in the presence of fertilizers. The fungus, however, improved plant growth by a lesser percentage than both fertilizers at both levels. The fungus unlike the fertilizers, suppressed nematode's disease severity. The suppressive effects of the fungus were, in most cases reduced by the fertilizers. In addition, the fertilizers significantly reduced root colonization of pyrethrum by the fungus. The nematodes, on the other hand, did not have any significant effects on root colonization by the fungus or on its ability to improve pyrethrum growth. The presence of nematodes in fertilizer or fertilizer-fungus-treated plants, however, significantly reduced pyrethrum growth. Efficacy of isolate KS14 to improve pyrethrum growth was tested in presence of maize and/or bean intercrops. Pyrethrum plants inoculated with 20g of KS14 and left to grow for 3 months were intercropped with maize and/or beans. Two months after planting the intercrops, pyrethrum dry shoot and fresh root weights were determined. Percent root colonization on the three crops by the fungus was also determined. In general, maize significantly reduced shoot and root weights of mycorrhized and non-mycorrhized plants. In addition, maize significantly reduced root colonization of pyrethrum. Beans on the other hand, significantly reduced shoot and root growth of mycorrhized plants but not of non-mycorrhized plants. Beans did not have any significant effects on root colonization of pyrethrum by the fungus. A combination of both intercrops had no significant effects on shoot weights of mycorrhized pyrethrum but reduced that of non-mycorrhized pyrethrum. Pyrethrum root colonization by the fungus was not affected by the presence of the two intercrops. Both maize and beans are hosts of the fungus.Item Interactions among leafhopper vector populations, maize streak virus disease, altitude and soil fertility(2011-08-03) Magenya, Oscar EnosLeafhoppers of the genus Cicadulina exclusively transmit Maize streak virus (MSV) disease which is an important constraint to maize production in Sub-Saharan Africa. Current literature indicates that agro-ecological factors influence leafhoppers and the MSV, but no information is available on the influence of altitude and soil nutrients on Cicadulina spp. and the MSV disease, and how these factors can be manipulated for disease control. The leaffhopper populations and the viral strains that they transmit were assessed to determine the geographical distribution and the prevalence of the MSV disease. Farm interviews, insect vector end soil sampling were carried out in six study regions to determine the level of farmer perception, leafhopper species distribution and soil nutrient levels in the regions. The selected regions were Bahari, Mwea, Githunguri, Oyani, Muhoroni and Kimilili in Kenya. The results indicated that farmers in Mwea and Oyani regions incur high yield losses of more than 40% due to M'W disease. Between 7% and 30% of farmers apply inorganic fertilizers, although the different s were not significantly different. The species of leafhoppers identified in the regions included cicadulina mbila Naude, C. storeyi China, C. chinai Ghauri and C. bipunctata (Melchar). The population sizes of the various Cicadulina species differed significantly (p = 0.021 and j = 0.006 respectively). Regression analysis showed that C. mbila numbers decreased significantly with altitude, and C. mbila correlated negatively with altitude. Most regions showed inadequate levels of phosphorus for plant growth, and the level of nitrogen and potassium differed significantly between the regions (p < 0.01). The viral isolates transmitted by C. mbila fro n Oyani region caused significantly higher percent disease incidence (87 %) than that from ( Githunguri, Muhoroni and Bahari regions (63, 60 and 53 % respectively). Screen house studies indicated that significantly low number of plants with MSV symptoms were recorded after high nitrogen treatment (75 kg N ha 1), compared to the rates of 0, 25 and 50 kg N ha 1. Plants that received 75 and 25 kg P ha treatments were significantly taller than those that did not receive any treatment. Nitrogen fertilizer correlated positively with the number of insects settling on the treated maize plants (r = 0.614; p < 0.011). Nymphal survival was significantly lower on the 25 Kg N treatment. However, plants treated with 25 kg N had comparatively higher percent lignin, and tannins, although differences of the later two were not significant. Pair wise correlation matrix analysis indicated that nitrogen treatment correlated positively with the percent nitrogen present in maize plant tissues, negatively with the neutral detergent fibres (r = - 0.510; p = 0 )43) and positively with the number of surviving nymphs (r = 0.502; p = 0.047). Acid detergent fibres correlated positively with the percent lignin (r = 0.815; p = 0.001). In addition, no significant relationship between the longevity of both male and female leafhoppers and the rate of phosphorus treatment was indicated. The findings of this study suggest that the application of, different rates of nitrogen and phosphorus fertilizers influence leafhopper behaviour and consequently the expression of MSV disease. This information can be used by the fertilizer industry to reformulate fertilizers, particularly for use in the management of vector borne diseases. Further research to design experimental systems of investigating responses of leafhoppers to global environmental changes is proposed. Such a study would assist in mitigating the effects of environmental change within the contest of establishing appropriate fertilizer regimes for crop productionItem Introgressing Genes for Maize Lethal Necrosis Disease Tolerance to Maize Inbred Lines and Awareness Evaluation in Selected Counties in Kenya(Kenyatta University, 2023) Peterson, Muchemi Kariuki; Joseph Wainaina Kamau; Mathew Piero NgugiMaize lethal necrotic disease remain a major biotic challenge facing maize production in Kenya and the entire Sub-Saharan region. The disease is caused by the synergistic co-infections of any member of potyviridae family and maize chlorotic mottle virus (MCMV). Improving maize cultivars through hybridization of single crosses and screening in a multiple agro ecological locations, is a fundamental stage in understanding projeny performance and disease reaction across the varying ecologies/locations.The identifications of the best parental combinations are important stages towards identification of MLND resistance maize cultivars in Kenya. The current study aimed at introgressing genes for maize lethal necrosis disease that is tolerance to maize inbred lines and determination of the level of awareness at Bomet and Nyandarua counties. Bomet County is the hot spot area for Maize lethal Necrotic Disease in Kenya, while Nyandarua county have a variation of agroecological zones imprptant for maize breeding. Structured questionnaire were used to collect data on farmers awareness and MLND managements among Bomet and Nyandarua Subcounties. A total of twenty-four inbred maize lines were collected at Kenya Agriculture Research and Livestock Organization Muguga Centre. In addition four commercial checks were also collected as positive and negative control for Maize Letahl Necrotic Diseases evaluation. The selected inbreds lines and control maize lines were evaluated in a green house environment at Kenyatta University. Field evaluation for MLND was also done at Bomet County. Ten inbred lines, six susceptible and four tolerant, were selected for hybridization. This was followed by identification of inbred lines and their hybrids with high combining ability for MLND resistance, yield, and other morpho-agronomic traits under natural MLND hotspot conditions. Twenty-four single cross hybrids were evaluated in MLND hotspot areas (Longisa and Itembe) Bomet county. The varieties of maize grown by the farmers differed significantly (P < 0.05) across all the five Sub counties in Bomet County. Majority of the farmers in Bomet County preferred genotype DK777 (23.91 %), SC DUMA 43 (8.26 %). Genotype DK777 was mostly prereferred by farmers due to MLND tolearant ability compared to other commercial hybrid. On the contrary, maize farmers in Nyandarua County preffered genotypes H614, H629 and H628 (26.27 %, 18.63 %, 16.87 % and 13.28 %), across all the Sub-counties (P < 0.05). The preference of H614 was due to high yielding compared to other maize varieties. Farmer’s knowledge, awareness and management varied significantly among sub counties evaluated. The screened inbred lines both at controlled environment and natural field, indicated several symptoms like mottling, dwarf maize plants, sterile tassels, short cob, and development of silk on ear position. Maize genotypes KUBT 2, KUBT 6 and KUBT 7 recorded tolerance in both green house and natural environment at Bomet County. Inbred lines KUBT6, KUBT7 and KUBT2 recorded the lowest severity levels after screening using natural conditions at Bomet County. Maize Hybrids KUBT2×KUBT9, KUBT6×KUBT9 and KUBT7×KUBT17 recorded negative Specific Combining Ability effect for severity scores which is an indicator of desirable genes tolerance to MLND. These single crosses hybrids are therefore, recommended for further evaluations to validate the stability for resistance to MLND in Kenya and Sub-saharan region towards food sustainability. The awareness evaluation of MLND among maize farmer, should be given first priorities toward management of MLND in Kenya.Item Metagenomic Analysis of Bacterial Communities in Drinking Water Distribution Systems in Mombasa County (Kenya)(Kenyatta University, 2016) Jeophita, Mwajuma JuneHygienic problems in drinking water distribution systems may originate from contamination by external microorganisms or growth of indigenous biomass. Among all water related disease outbreaks, 33% waterborne diseases were caused by-contaminated source water, 39% by inadequate or interrupted treatment processes and 18% by distribution systems and premise --plumbing deficiencies (Craun et 'al., 2010). The Mombasa County water distribution systems have since inception undergone a sanitary survey and there has been no information on the bacterial community composition therein . .The primary focus of this study therefore was to generate detailed information on the genome information stored within the water distribution system, microbiome. This was achieved through an analysis of the 16S rRNA phylotypes of the microbes present within the microbial community of21 water and biofilm samples collected from Mzima and Baricho water lines, which have been operational for more than 50 years, making them excellent sources of mature distribution system biofilms. Physicochemical characteristics of the water were determined by a portable Palin Photometer and Atomic Absorption Spectrophotometer; while bacterial taxonomic affiliations were analyzed using 16S rRNA based 454-FLX Titanium pyrosequencing. Water from both water lines registered pH, nitrates, phosphates and residual chlorine levels that were within the limits stipulated for drinking water by the Kenya Bureau of Standards (KEBS). All Baricho line samples had iron and lead levels way above the maximum allowable limit of 0.05 mg L-1• Nitrates, iron and temperature correlated positively with bacterial community composition and diversity in all samples as shown by Canonical correspondence analysis (Mantel test: r = 0.27, P = 0.001). Pyrosequencing yielded 27,937 sequences, which were denovo clustered into 2,294 unique operational taxonomic units (OTUs) based on their sequence similarity (3%). A total of 20 bacterial phyla and 6 candidate phyla were identified from pooled samples and were dominated by the Proteobacteria (73.2%), Firmicutes (13.4%), Bacteriodetes (5.9%) and Candidate divisions at 0.9% of the total phylotypes. Renyi diversity profiles t' demonstrated that all sampled sites regardless of source or type have larger species richness, but lower species evenness. Shannon-Wiener diversity (H) index of each sampling site ranged from 0.00 to 1.725. The highest bacterial diversity was found in Baricho water (1.725) and Mzima biofilms (1.391). Biofilms featured characteristically higher bacterial diversity, richness and abundance than bulk water. Bulk water was predominated by Nitrospirae (20.2%), Betaproteobacteria (15.9%) and Alphaproteobacteria (6.4%), while Favobacteria (8.6%), Deltaproteobcteria (3.2%), bacteria NP L. UPA2 and Candidate division OD! were characteristic of biofilms. Redundancy analysis indicated substantial comparative differences in water and biofilms bacterial community composition among the two water lines. Nitrospirae, Elusimicrobia, Cyanobacteria, Gemmatimonadetes, NP-UPA2, and Candidate Divisions TM7, OP11 and OD1 were present only at source but not at endpoints. Differences in community structure and abundance were noted between Baricho water line source and endpoint water and biofilms bacterial composition (p= 0.013). A total of 140 phylotypes of potentially pathogenic species including; Pseudomonas, Escherichia, Shigella, Aeromonas, Enterobacter and Bdelovibrio were identified. Metagenome analyses also confirmed the ubiquity of mycobacteria in drinking water distribution systems. Maintainance of the integrity of water systems, periodic monitoring and effective treatment techniques should take precedence in water delivery services to reduce the risk of contaminating the drinking water with pathogenic microorganisms.Item Neem seed for the management of the banana weevil, cosmopolotes sordidus germar (coleoptera: curculionidae)and banana parasitic nematode complex(2012-04-04) Musabyimana, ThaddéeThe study was conducted in Western Kenya, a prime banana growing area during the period of May 1996 to February 1999. The objectives were to control the banana weevil and parasitic nematodes with neem materials, thereby reducing yield losses and contributing to sustainable banana production. The repellent, antifeedant, ovipositional deterrent, and growth inhibitory effects of powdered neem seed (NSP), Kernel (NKP), cake (NC) and neem oil (NO) on Cosmopolites sordidus and its population build-up were studied in the laboratory and outdoors tests at ICIPE's Mbita point field station (MPFS). In choice tests, 48h after release, less than 30% of weevils settled under neem-treated banana corms while more than 75% settled under untreated corms. In a feeding test, weevil larvae did not feed or fed little on neem-treated corms. Larvae caused little damage to neem-treated corms, but untreated corms were heavily damaged, indicating a strong repellent and antifeedant effect of neem seed derivatives on C. sordidus. Compared with the untreated control, 3-10 times fewer eggs were laid by female in neem-treated corms. Egg hatchability was less than 25% in neem- treated corms and more than 50% in the control. Neem treatments also inhibited larval growth and development. Forty to 60% of 2nd-instar larvae died in 14 day when confined to neem-treated banana pseudostems, the survivors were small in body size and weighed 4 to 6 times less than those in the control where less than 20% larvae died and adults were recovered. The higher the concentration of neem materials, the higher was the severity of effects. Efficacy of neem materials against the banana weevil and parasitic nematodes was evaluated under controlled pest infestation levels at MPFS. Effective rates, methods and frequency of application of the selected neem materials were determined at MPFS and in Farmers' fields, under different levels of soil fertility and pests infestation. In a pot experiment, four weeks after planting, NSP, NKP, or NC was applied at 5g per plants inoculated with 500 nematodes and 5 pairs (females and Males) of the banana weevil. Compared with control, 1.5 months after the treatment, neem materials application significantly reduced the nematode population and weevil damage on a par with Furadan applied at 5 g/plant. Similar results were obtained with the application of neem materials to pared or unpared banana suckers planted in 100 or 200l drum's capacity and inoculated with 2000 nematodes and 5 pairs (female and males) of the banana weevil per drum. NSP-or NC- treated unpared suckers supported much fewer nematodes than the pared treated suckers with same neem products, obviating the need for paring of suckers. NKP and NO applications were toxic to the banana plant and were excluded from further testing. Soil application of powered NSP or NC against the banana pests was more effective than their application in aqueous forms. Application of NSP or NC at planting time and then at 1, 2, 3, or 4- month intervals to plants grown under controlled pest infestations in drums significantly reduced nematode density and the weevil damage. Similarly, in farmers' fields, soil application of NSP or NC at 60, 80 or 100 g/mat at planting and then at 4 month-interval significantly reduced the weevil and nematode damage. Although the application of NSP or NC at 200 to 400 g/mat at 6 month-intervals significantly reduced the nematode population and weevil damage, they were toxic to the banana plant. Application of NSP or NC at 60, 80 or 100 g/mat at 4-month intervals to a fertile soil with a moderate pest load, increased yields by 27-50% over the control during the 1st crop and by 30-60% during the 2nd crop. Furadan increased the fruit yield by 27% over the control in the 1st crop but dropped down to -2% in the 2nd crop. Under low soil fertility and high pest infestation levels, the neem treatments also controlled the pests and markedly increased the yield 7 to 10 times more than that in the control during the first crop. During the second crop, all plants in the control plots dried up before fruiting, but neem-treated plants continued to produce bunches. Depending on the soil fertility and doses of application, net gain over the control obtained with the application of NSP or NC ranged from US $ 70 and US $ 800 per hectare. However, a loss of US $ 700/ha was observed with the Furadan application. Neem application of doses higher than 100 g/mat was also uneconomical. The beneficial effects of neem seed materials application on the banana plant growth, pest control, and implications of these findings in the banana pest management and further areas of investigation are discussed.