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Muturi P.W.,Embu University College | Mgonja M.,Alliance for a Green Revolution in Africa | Rubaihayo P.,Makerere University
International Journal of Tropical Insect Science | Year: 2014

Lepidopteran stemborers, mainly the African stemborer Busseola fusca Fuller and spotted stemborer Chilo partellus Swinhoe, are among the economically important pests of sorghum in Kenya. Identification of sources of resistance is valuable for the development of an integrated pest management strategy to minimize losses. This study evaluated 27 genotypes with artificial infestations (mostly for tolerance) in two different agroecological zones. Data on damage from leaf feeding, dead heart, exit holes, and stem tunnelling; plant height; days to 50% flowering; total grain yield; and hundred-grain mass were collected. Significant differences (P< 0.001) were observed in all the traits evaluated, except leaf damage, under infestation by C. partellus. Classification into different categories of resistance revealed genetic variation. Genotypes resistant/moderately resistant to both pests were as follows: ICSA 464>ICSB 464>ICSB 467>ICSA 472>ICSB 472>ICSA 473>ICSA 474>IESV 91131 DL>Macia. The relative contributions of the damage parameters to grain yield loss were partitioned into direct and indirect relationships by path coefficient analysis with grain yield as the resultant variable. The results revealed that damage from exit holes, dead heart, leaf feeding and stem tunnelling had a negative indirect effect on grain yield. The identified genotypes can be used to enhance resistance to both pests in susceptible cultivars that farmers prefer. © ICIPE 2014. Source


Lagerlof J.,Swedish University of Agricultural Sciences | Ayuke F.,Swedish University of Agricultural Sciences | Ayuke F.,University of Nairobi | Bejai S.,Swedish University of Agricultural Sciences | And 5 more authors.
Applied Soil Ecology | Year: 2015

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. © 2015 Elsevier B.V. Source


Kilongosi M.W.,Maseno University | Budambula V.,Technical University of Mombasa | Lihana R.,Kenya Medical Research Institute | Musumba F.O.,Maseno University | And 6 more authors.
BMC Infectious Diseases | Year: 2015

Background: Information about HBV sero-markers, infection stages and genotypes in HIV-1 infected and uninfected injection and non-injection drug users (IDUs) in Kenya remains elusive. Methods: A cross-sectional study examining HBV sero-marker, infection stages and genotypes was conducted among HIV-1 infected and uninfected, respectively, IDUs (n=157 and n=214) and non-IDUs (n=139 and n=48), and HIV-1 uninfected non-drug using controls (n=194) from coastal, Kenya. HBV sero-marker and infection stages were based on HBV 5-panel rapid test plasma sero-reactivity. DNA was extracted from acute and chronic plasma samples and genotypes established by nested-PCR and direct sequencing. Results: HBsAg positivity was higher in HIV-1 infected IDUs (9.6%) relative to HIV-1 uninfected IDUs (2.3%), HIV-1 infected non-IDUs (3.6%), HIV-1 uninfected non-IDUs (0.0%) and non-drug users (2.6%; P=0.002). Contrastingly, HBsAb positivity was higher in HIV-1 uninfected IDUs (14.6%) and non-IDUs (16.8) in comparison to HIV-1 infected IDUs (8.3%), and non-IDUs (8.6%), and non-drug users (8.2%; P=0.023). HBcAb positivity was higher in HIV-1 infected IDUs (10.2%) compared to HIV-1 uninfected IDUs (3.3%), HIV-1 infected non-IDUs (6.5%), HIV-1 uninfected non-IDUs (2.1%) and non-drug users (4.6%; P=0.038). Acute (5.7%, 1.4%, 0.0%, 0.0% and 1.5%) and chronic (5.1%, 0.9%, 3.6%, 0.0% and 1.5%) stages were higher in HIV-1 infected IDUs, compared to HIV-1 uninfected IDUs, HIV-1 infected and uninfected non-IDUs and non-drug users, respectively. However, vaccine type response stage was higher in HIV-1 uninfected IDUs (15.4%) relative to HIV-1 infected IDUs (6.4%), and HIV-1 infected (6.5%), and uninfected (10.4%) non-IDUs, and non-drug users (5.7%; P=0.003). Higher resolved infection rates were also recorded in HIV-1 uninfected IDUs (11.2%) compared to HIV-1 infected IDUs (8.3%), and HIV-1 infected (7.2%), uninfected (6.3%) non-IDUs, and non-drug users (6.7%; P=0.479), respectively. Only A1 genotype showing minimal diversity was detected among the study participants. Conclusion: HBV sero-markers and infection staging are valuable in diagnosis and genotyping of HBV infections. Among IDUs, higher HBsAg and HBcAb positivity in HIV-1 infected and higher HBsAb positivity in HIV-1 negative IDUs suggests frequent exposure. Additionally, HBV genotype A is the dominant circulating genotype in both high and low risk populations of Kenya. © 2015 Webale et al. Source


Dadheech P.K.,Leibniz Institute of Freshwater Ecology and Inland Fisheries | Dadheech P.K.,Central University of Rajasthan | Dadheech P.K.,Government of Rajasthan | Glockner G.,University of Cologne | And 10 more authors.
FEMS Microbiology Ecology | Year: 2013

Hot springs and saline-alkaline lakes of East Africa are extreme habitats regarding temperature, or salinity and pH, respectively. This study examines whether divergent habitats of Lake Bogoria, Kenya, impacts cyanobacterial community structure. Samples from the hot springs, pelagic zone and sediment were analysed by light microscopy, multilocus 454-amplicons sequencing and metagenomics to compare the cyanobacterial diversity. Most of the phylogenetic lineages of Cyanobacteria occurred exclusively in the Bogoria hot springs suggesting a high degree of endemism. The prevalent phylotypes were mainly members of the Oscillatoriales (Leptolyngbya, Spirulina, Oscillatoria-like and Planktothricoides). The Chroococcales were represented by different clades of Synechococcus but not a single phylotype clustered with any of the lineages described earlier from different continents. In contrast, we found that the pelagic zone and the sediments were inhabited by only a few taxa, dominated by Arthrospira and Anabaenopsis. Arthrospira, the main food base of Lesser Flamingo, was detected in all three habitats by amplicons pyrosequencing, indicating its resilience and key role as a primary producer. Despite the close connection between the three habitats studied, the cyanobacterial communities in the hot springs and lake differed considerably, suggesting that they are unable to adapt to the extreme conditions of the neighbouring habitat. © 2013 Federation of European Microbiological Societies. Published by John Wiley & sons Ltd. Source


Garibaldi L.A.,National University of Rio Negro | Bartomeus I.,CSIC - Donana Biological Station | Bommarco R.,Swedish University of Agricultural Sciences | Klein A.M.,Albert Ludwigs University of Freiburg | And 37 more authors.
Journal of Applied Ecology | Year: 2015

Understanding the relationships between trait diversity, species diversity and ecosystem functioning is essential for sustainable management. For functions comprising two trophic levels, trait matching between interacting partners should also drive functioning. However, the predictive ability of trait diversity and matching is unclear for most functions, particularly for crop pollination, where interacting partners did not necessarily co-evolve. World-wide, we collected data on traits of flower visitors and crops, visitation rates to crop flowers per insect species and fruit set in 469 fields of 33 crop systems. Through hierarchical mixed-effects models, we tested whether flower visitor trait diversity and/or trait matching between flower visitors and crops improve the prediction of crop fruit set (functioning) beyond flower visitor species diversity and abundance. Flower visitor trait diversity was positively related to fruit set, but surprisingly did not explain more variation than flower visitor species diversity. The best prediction of fruit set was obtained by matching traits of flower visitors (body size and mouthpart length) and crops (nectar accessibility of flowers) in addition to flower visitor abundance, species richness and species evenness. Fruit set increased with species richness, and more so in assemblages with high evenness, indicating that additional species of flower visitors contribute more to crop pollination when species abundances are similar. Synthesis and applications. Despite contrasting floral traits for crops world-wide, only the abundance of a few pollinator species is commonly managed for greater yield. Our results suggest that the identification and enhancement of pollinator species with traits matching those of the focal crop, as well as the enhancement of pollinator richness and evenness, will increase crop yield beyond current practices. Furthermore, we show that field practitioners can predict and manage agroecosystems for pollination services based on knowledge of just a few traits that are known for a wide range of flower visitor species. Despite contrasting floral traits for crops world-wide, only the abundance of a few pollinator species is commonly managed for greater yield. Our results suggest that the identification and enhancement of pollinator species with traits matching those of the focal crop, as well as the enhancement of pollinator richness and evenness, will increase crop yield beyond current practices. Furthermore, we show that field practitioners can predict and manage agroecosystems for pollination services based on knowledge of just a few traits that are known for a wide range of flower visitor species. © 2015 British Ecological Society. Source

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