Browsing by Author "Muturi, John J."
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Item Collembola Density and Diversity along a Gradient of Land- Use Types in Embu District, Eastern Kenya(2009) Muturi, John J.; Mbugi, J.P.; Mueke, J.M.; Lagerlóf, Jan; Mungatu, J.K.; Nyamasyo, G.; Gikungu, M.Populations of soil-dwelling Collembola were monitored on a land use gradient ranging from Natural forests to intensively cultivated land during the wet season October-November, 2007 and dry season February-March, 2008. Eight land use types (LUTs) which included stands of; Eucalyptus saligna, Vitex keniensis, Pennisetum purpureum, indigenous forest, fallow fields, Cammelia sinensis, Coffea africana and Zea mays intercropped with Phaseolus vulgaris were sampled for Collembola in Embu district. Collembola population densities of (15,111 M²) were collected in the study area. The Collembolan populations were lower in all sites during the dry season (5,445 M²), compared to those of wet season (9,666 M²). However, the highest Collembolan population was observed in undisturbed indigenous forest (38,089 M²) during the dry season. A total of seventeen genera in seven families were recorded. The genus Isotomiella was the most abundant followed by Cryptopygus, Folsomina and Parisotoma respectively. Results from this study revealed that abundance, diversity and species richness decreased along land use gradient with agro-based LUTs presenting an impoverished community. The level of organic matter as indicated by proportion of Carbon and Nitrogen in LUTs such as Indigenous forest, Eucalyptus forest and Cammelia sinensis seemed to influence highly Collembolan assemblages. The study concludes that land use intensification (land disturbance) negatively influences the abundance and species richness of soil Collembolan communities.Item Collembola Richness and Diversity along A Land-Use Intensity Gradient in Taita, Kenya(2009) Muturi, John J.; Mbugi, J.P.; Mueke, J.M.; Lagerlöf, Jan; Mungátu, J.K.; Nyamasyo, G.; Gikungu, M.Soil Collembola communities were sampled along a gradient of land use intensification in Taita-Taveta, Wundanyi division, Coast Province during the wet season (October-November 2007) and dry season (February- March 2008). This gradient ranged from Natural undisturbed land use to intensively cultivated (disturbed) horticulture fields. The eight land use types (LUTs) were stands of (1) Pinus patula, (2) Cypress lusitanica, (3) Indigenous forest, (4) Fallow, (5) Pennisetum purpureum, (6) horticulture fields, (7) Coffea africana and (8) Zea mays intercropped with Phaseolus vulgaris. The dynamic behavioural modified Berlesse funnel technique was used for collembolan extraction from soil. Collembola were identified to genus level. 11462 individuals per m² were identified from 30 genera. Generally, low Collembolan population were recorded in the wet season of 2007 with density of 2618 individuals per m² compared to density of 8844 individuals per m² in the dry season of 2008 sampled in all the land use types (LUUs). The highest Collembolan population was recorded in Cypress lusitanica with a density of 3781 individuals per m² and lowest in Zea mays intercropped with Phaseolus vulgaris with a density of 198 individuals per m². A total of 30 genera in 11 families were recorded. The genus Cryptopygus was the most commonly sampled followed by Thalassaphorura, Parisotoma, Lepidocyrtus and Folsomides (37.2%, 17.7%, 8.5%, 6.1% and 5.5%) respectively. Land use type like Pinus patula, Cypress lusitanica, and Pennisetum purpureum had high carbon, nitrogen and acidity, supported high numbers and diverse Collembolan assemblages. The results show that both density and diversity of soil the Collembolan communities were higher in undisturbed sites than in disturbed land use types. In conclusion the Collembolan communities are negatively impacted by land use intensification.Item Combining Host Plant Resistance, Selective Insecticides, and Biological Control Agents for Integrated Management of Tuta absoluta(Hindawi, 2020-08) Nderitu, Peris W; Jonsson, Mattias; Arunga, Ester E.; Otieno, Mark; Muturi, John J.; Wafula, Geoffrey O.Combination of pest management strategies that minimize pesticide use and conserve natural enemies is important for a sustainable environment. Overreliance on synthetic insecticides in the management of Tuta absoluta has led to pesticide resistance leading to difficulties in managing the pest. In this regard, alternative measures need to be put in place to reduce the effects of this pest. ,e objective of this study was, therefore, to assess the effectiveness of host plant resistance, biological control, and selective insecticides when used in combination, in the management of T. absoluta in tomato production. ,e study was set up in a greenhouse in a completely randomized design involving two tomato varieties, an insecticide (chlorantraniliprole), and a biological control agent(Macrolophus pygmaeus), applied singly or in combination. Data were collected on T. absoluta damage from the lower, intermediate, and upper leaves. ,e results from this study show that a combination of insecticide with a moderately resistant variety had a significantly lower T. absoluta damage as compared with a susceptible variety combined with an insecticide. However, the moderately resistant variety when combined with insecticide showed no effect when the biological control agent was added. ,e susceptible variety significantly reduced T. absoluta damage when combined with the biological control agent. ,ese results indicate that treatment combinations in insect pest management can be utilized. ,e present study results indicate that using a moderately resistant variety (Riogrande VF) in combination with the insecticide chlorantraniliprole (Coragen®) and a susceptible variety (Pesa F1) in combination with the biological control agent (M. pygmaeus) can improve T. absoluta management. Under good habitat management, the susceptible variety will perform equally as the moderately resistant variety due to suppression of the T. absoluta populations by natural enemies. ,ese findings show the importance of environmental conservation both by enhancing natural enemy abundance and use of selective insecticide in the management of T. absoluta in tomato production. Combinations in this present study are likely to reduce insecticide doses, thereby reducing the cost of production and enhancing environmental compatibility with natural enemies.Item Effect of Integrated Soil Fertility Management Interventions on the Abundance and Diversity of Soil Collembola in Embu and Taita Districts, Kenya(2011) Muturi, John J.; Mbugi, J.P.; Mueke, J.M.; Lagerlöf, J.; Mungátu, J.K.; Nyamasyo, G.; Gikungu, M.The study aimed at identifying soil fertility management practices that promote the Collembola population, diversity and survival in the soil. Soil samples were randomly collected from on farm plots amended with: 1-Mavuno ((Ma)-is a compound fertilizer containing 26% Potassium, 10% Nitrogen, 10% Calcium, 4% Sulphur, 4% Magnesium and trace elements like Zinc, Copper, Boron, Molybdenum and Manganese)), 2-Manure (Mn), 3-Trichoderna (Tr) inoculant (is a soil and compost-borne antagonistic fungus used as biological control agent against plant fungal diseases), 4-Farmers practice ((FP) where Tripple Super Phosphate (T.S.P.) and Calcium Ammonium Nitrate (C.A.N.) fertilizers are applied in the soil in mixed form), 5-Tripple Super Phosphate (T.S.P.), 6-Calcium Ammonium Nitrate (C.A.N.). These treatments were compared with 7-Control (Co) (where soil fertility management interventions where not applied). Soil Collembola were extracted using dynamic behavioural modified Berlese funnel and identified to the genus level. Occurrence of Collembola was significantly affected by soil fertility amendments in both Taita and Embu study sites (P<0.05). Twenty two genera of soil dwelling Collembola were recorded, with control and organic manure treated plots recording high diversity with a Shannon 1.86 in Embu and a Shannon 2.09 in Taita, respectively. There was significant difference (P<0.05) of seasonality on soil Collembola occurrence at both Embu and Taita. Application of cow manure and addition of Trichoderma inoculants promoted the soil Collembola. The study has demonstrated that application of organic amendments encouraged the soil Collembola while inorganic fertilizers negatively impacted on these soil organisms.Item Potential side effects of biocontrol and plant-growth promoting Bacillus amyloliquefaciens bacteria on earthworms(Elsevier, 2015-08) Lagerlöfa, J.; Ayukea, F.; Bejaib, S.; Jorgec, G.; Lagerqvista, E.; Meijerb, J.; Muturi, John J.; Söderlunda, S.Many bacteria strains are now successfully used for plant-growth promotion (PGPR) and as biocontrol agents (BCA) against plant diseases. Mechanisms behind their action involve production of enzymes and antibiotics, which in high concentrations could also affect non-target organisms hence the biodiversity and processes in the soil. Despite these potential negative side effects, there is little research done on the subject to confirm whether they are significant. In three laboratory experiments, we tested the effect of the bacterial BCA Bacillus amyloliquefaciens UCMB5113 (BA) on two earthworm species, common in agricultural soils in temperate regions of the world and representing different ecological groups; one anecic (Aporrectodea longa) and one endogeic species (Aporrectodea caliginosa). The earthworms were kept in replicated pots containing soil from local agricultural fields. They were fed on cow manure, and exposed to BA by (1) dipping into a BA solution (short-term external exposure in high concentration), (2) mixing BA solution into the soil (long term external and internal exposure) and (3) feeding earthworms with BA infested plant litter (internal exposure of the gut). After 1–2 months, survival, growth and reproduction of the earthworms were recorded. We found no effect of the treatments as compared to control without BA amendments. We conclude that the use of high doses of BA with concentrations at the same magnitude as maximally expected when the bacteria are used as PGPR and BCA, is not harmful to the soil dwelling earthworms tested in this project. Further studies of the ecological effects of PGPR and BCA bacteria on other non-target soil organisms are encouraged. The development of sustainable agricultural systems, where ecosystem services are optimized, has to be aided by a deeper knowledge of the combined effect of bacteria and earthworms on the promotion of plant health