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Articles 301 - 330 of 429

Full-Text Articles in Agricultural Science

Evaluation Of Acaricide-Treated String Curtains For Control Of Two-Spotted Spider Mite Tetranychus Urticae Koch (Acari: Tetranychidae) On Greenhouse Roses And Impact Of The String Curtain On The Predatory Mite Phytoseiulus Persimilis Athias-Henriot (Acari: Phytoseiidae), Emilie M. Deletre, Romain Bonafos, Thibaud Martin Jan 2014

Evaluation Of Acaricide-Treated String Curtains For Control Of Two-Spotted Spider Mite Tetranychus Urticae Koch (Acari: Tetranychidae) On Greenhouse Roses And Impact Of The String Curtain On The Predatory Mite Phytoseiulus Persimilis Athias-Henriot (Acari: Phytoseiidae), Emilie M. Deletre, Romain Bonafos, Thibaud Martin

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Foliar sprays of pesticides are frequently used to control two-spotted mites on rose flowers, but these also destroy predatory mites and pose a high risk of contamination for humans and the environment. Using a novel approach to avoid spray applications on rose plants, modified acaricide-treated string curtains were adapted to control the pest. Two main aims of this study were: (i) to identify the lethal concentration of string curtains treated with propargite, dicofol, flufenoxuron, acrinathrin or tau-fluvalinate (τ-fluvalinate) on Tetranychus urticae, and (ii) to test the design (feasibility) and efficiency of the string curtains to trap the phytophagous mites on …

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Integrated Soil Fertility Management: Aggregate Carbon And Nitrogen Stabilization In Differently Textured Tropical Soils, R. M. Gentile, B. Vanlauwe, J. Six Dec 2013

Integrated Soil Fertility Management: Aggregate Carbon And Nitrogen Stabilization In Differently Textured Tropical Soils, R. M. Gentile, B. Vanlauwe, J. Six

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Soil organic matter is important to improve and sustain soil fertility in tropical agroecosystems. The combined use of organic residue and fertilizer inputs is advocated for its positive effects on short-term nutrient supply, but the effect of the integrated use on long-term stabilization of soil organic C and N is still unclear. We conducted a 1.5-y soil incubation experiment with maize (Zea mays) residue and urea fertilizer to examine the stabilization of C and N in four Sub-Saharan African soils differing in texture (sand, sandy loam, clay loam, and clay). The inputs were enriched with 13C and 15N in a …

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Seasonal Abundance Of Western Flower Thrips And Its Natural Enemies In Different French Bean Agroecosystems In Kenya, J. O. Nyasani, R. Meyhöfer, S. Subramanian, H. M. Poehling Sep 2013

Seasonal Abundance Of Western Flower Thrips And Its Natural Enemies In Different French Bean Agroecosystems In Kenya, J. O. Nyasani, R. Meyhöfer, S. Subramanian, H. M. Poehling

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The seasonal abundance of western flower thrips (WFT) [Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)] and its natural enemies on French beans in two agro-ecological zones (AEZs) (high and mid altitude) in Kenya, was studied in three growing cycles from January to December 2009. French beans were sampled every 2 weeks for WFT and natural enemies. Results show that colonization of French beans with WFT in both farm scales studied in the two AEZs started at 2- to 3-leaf stage. There was an increase in the population density of WFT from budding stage to podding/flowering stage, and it declined at crop senescence. …

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Phosphorus Agronomic Efficiency In Maize-Based Cropping Systems: A Focus On Western Kenya, J. Kihara, S. Njoroge Aug 2013

Phosphorus Agronomic Efficiency In Maize-Based Cropping Systems: A Focus On Western Kenya, J. Kihara, S. Njoroge

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Phosphorus (P) is facing a quantity and quality supply issue and increasing its use efficiency is important for its continued use and profitability in crop production. The objective of this study was to determine how agronomic efficiency of P (PAE) in different environments and management systems in western Kenya is affected by N application, inherent soil fertility and organic resources. We used data constituting over 2700 data points from 126 farm fields of 25 different studies conducted from 1996 to 2009. Potassium (K) deficiency is negligible in western Kenya while ommission of P and N result in a 50% and …

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Pushing The Envelope? Maize Production Intensification And The Role Of Cattle Manure In Recovery Of Degraded Soils In Smallholder Farming Areas Of Zimbabwe, Leonard Rusinamhodzi, Marc Corbeels, Shamie Zingore, Justice Nyamangara, Ken E. Giller Jun 2013

Pushing The Envelope? Maize Production Intensification And The Role Of Cattle Manure In Recovery Of Degraded Soils In Smallholder Farming Areas Of Zimbabwe, Leonard Rusinamhodzi, Marc Corbeels, Shamie Zingore, Justice Nyamangara, Ken E. Giller

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Soil fertility decline is a major constraint to crop productivity on smallholder farms in Africa. The objective of this study was to evaluate the long-term (up to nine years) impacts of nutrient management strategies and their local feasibility on crop productivity, soil fertility status and rainfall infiltration on two contrasting soil types and different prior management regimes in Murehwa, Zimbabwe. The nutrient management strategies employed in the study were: a control with no fertiliser, amendments of 100kg Nha-1, 100kg N+lime, three rates of manure application (5, 15 and 25tha-1) in combination with 100kg Nha-1, and three rates of P fertiliser …

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Differences In Essential Oil Content Of Berries And Leaves Of Solanum Sarrachoides (Solanaceae) And The Effects On Oviposition Of The Tomato Spider Mite (Tetranychus Evansi), Lucy K. Murungi, Hillary Kirwa, Baldwyn Torto Apr 2013

Differences In Essential Oil Content Of Berries And Leaves Of Solanum Sarrachoides (Solanaceae) And The Effects On Oviposition Of The Tomato Spider Mite (Tetranychus Evansi), Lucy K. Murungi, Hillary Kirwa, Baldwyn Torto

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Essential oils from leaves and berries of Solanum sarrachoides were obtained by hydro-distillation, analyzed by GC-MS and tested for oviposition deterrence against Tetranychus evansi. Plant oils comprised mainly of monoterpenes and fatty acids, but differed in terms of their relative abundance. The leaf oil contained mainly camphor (34.1%), limonene (8%), decanoic acid (9.3%) and hexadecanoic acid (7.3%). The berry oil contained mainly fatty acids (>20%) including hexadecanoic acid (9.8%) and dodecanoic acid (5.9%), hydrocarbons (>10%) and (E)-β-linalool (3.1%). In oviposition deterrence assays, the leaf essential oil and individual major monoterpenes compared favorably with the two positive controls, neem …

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Effects Of Mulching, N-Fertilization And Intercropping With Desmodium Uncinatum On Striga Hermonthica Infestation In Maize, Charles A.O. Midega, Jimmy Pittchar, Daisy Salifu, John A. Pickett, Zeyaur R. Khan Feb 2013

Effects Of Mulching, N-Fertilization And Intercropping With Desmodium Uncinatum On Striga Hermonthica Infestation In Maize, Charles A.O. Midega, Jimmy Pittchar, Daisy Salifu, John A. Pickett, Zeyaur R. Khan

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The parasitic weed Striga hermonthica is a major constraint to maize production in sub-Saharan Africa and causes serious food insecurity. We discovered serendipitously an effective control method for the weed that involves intercropping cereals with the fodder legume, silverleaf desmodium, Desmodium uncinatum (Jacq.) DC., through mechanisms that involve soil shading and nitrogen fixation. In the current study we investigated long-term effects of inorganic nitrogen (N), mulching and D. uncinatum, singly and in combinations, on S. hermonthica infestation, maize plant growth and grain yields. Treatments comprised sole maize with and without 120 kg N/ha; sole maize plots covered with maize straw …

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Two Sugar Isomers Influence Host Plant Acceptance By A Cereal Caterpillar Pest, G. Juma, M. Thiongo, L. Dutaur, K. Rharrabe, F. Marion-Poll, B. Le Ru, G. Magoma, J. F. Silvain, P. A. Calatayud Feb 2013

Two Sugar Isomers Influence Host Plant Acceptance By A Cereal Caterpillar Pest, G. Juma, M. Thiongo, L. Dutaur, K. Rharrabe, F. Marion-Poll, B. Le Ru, G. Magoma, J. F. Silvain, P. A. Calatayud

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Abstract Plant sugars are often considered as primary feeding stimuli, conditioning host plant acceptance by herbivorous insects. Of the nine sugars identified from methanolic extracts of seven grass species, only turanose, a sucrose isomer, was negatively correlated with the survival and growth of the noctuid larva of cereal stemborer, Busseola fusca. Sucrose was the most abundant sugar, although it did not vary significantly in concentration among the plant species studied. Using Styrofoam™ cylinders impregnated with increasing concentrations of turanose or sucrose, the two sugars had opposing effects: turanose appeared phagodeterrent while sucrose was phagostimulatory. Electrophysiological studies indicated that B. fusca …

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Farmers' Perceptions Of Cotton Pests And Their Management In Western Kenya, Charles A.O. Midega, Isaac M. Nyang'au, Jimmy Pittchar, Michael A. Birkett, John A. Pickett, Miguel Borges, Zeyaur R. Khan Dec 2012

Farmers' Perceptions Of Cotton Pests And Their Management In Western Kenya, Charles A.O. Midega, Isaac M. Nyang'au, Jimmy Pittchar, Michael A. Birkett, John A. Pickett, Miguel Borges, Zeyaur R. Khan

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Cotton (Gossypium hirsutum L.) production in western Kenya is severely affected by insect pests, resulting in poor yields in spite of the growing demand for the commodity. One of the key constraints to establishing effective pest management approaches for smallholder farmers is the lack of adequate information about farmers' knowledge, perceptions and practices in pest management. This study was therefore conducted to (1) evaluate farmers' knowledge and perceptions of cotton pests; (2) examine farmers' current practices in managing cotton pests; (3) identify pest management challenges and intervention opportunities in order to develop efficient integrated pest management (IPM) approaches. A total …

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The Impact Of Desmodium Spp. And Cutting Regimes On The Agronomic And Economic Performance Of Desmodium-Maize Intercropping System In Western Kenya, M. Kifuko-Koech, P. Pypers, J. R. Okalebo, C. O. Othieno, Z. R. Khan, J. A. Pickett, A. K. Kipkoech, B. Vanlauwe Oct 2012

The Impact Of Desmodium Spp. And Cutting Regimes On The Agronomic And Economic Performance Of Desmodium-Maize Intercropping System In Western Kenya, M. Kifuko-Koech, P. Pypers, J. R. Okalebo, C. O. Othieno, Z. R. Khan, J. A. Pickett, A. K. Kipkoech, B. Vanlauwe

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Low soil fertility, stemborers (particularly, Chilo partellus) and Striga weeds (Striga hermonthica and Striga asiatica) are major limitations to production of maize in western Kenya. The " Push-Pull" technology ("PPT") has been described as an appropriate innovative technology capable of addressing these constraints. The technology involves intercropping maize with Desmodium and planting Napier grass (Pennisetum purpureum) around the intercrop, but in the current study a modified PPT was used and Napier grass was not included. Field trials were conducted in two locations in western Kenya during 4 subsequent seasons to test the hypothesis that maize yield, the degree of Striga …

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Genetic Structure And Mating System Of Wild Cowpea Populations In West Africa, Eric B. Kouam, Remy S. Pasquet, Pascal Campagne, Jean Baptiste Tignegre, Kevin Thoen, Remi Gaudin, Jeremy T. Ouedraogo, Abdulai B. Salifu, Geoffrey M. Muluvi, Paul Gepts Jul 2012

Genetic Structure And Mating System Of Wild Cowpea Populations In West Africa, Eric B. Kouam, Remy S. Pasquet, Pascal Campagne, Jean Baptiste Tignegre, Kevin Thoen, Remi Gaudin, Jeremy T. Ouedraogo, Abdulai B. Salifu, Geoffrey M. Muluvi, Paul Gepts

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Background: Cowpea is a highly inbred crop. It is part of a crop-weed complex, whose origin and dynamics is unknown, which is distributed across the African continent. This study examined outcrossing rates and genetic structures in 35 wild cowpea (Vigna unguiculata ssp. unguiculata var. spontanea) populations from West Africa, using 21 isozyme loci, 9 of them showing polymorphism.Results: Outcrossing rates ranged from 1% to 9.5% (mean 3.4%), which classifies the wild cowpea breeding system as primarily selfing, though rare outcrossing events were detected in each population studied. Furthermore, the analyses of both the genetic structure of populations and the relationships …

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Identification Of Root-Knot Nematode Species Occurring On Tomatoes In Kenya: Use Of Isozyme Phenotypes And Pcr-Rflp, Rael Birithia, Wanjohi Waceke, Peter Lomo, Daniel Masiga Jun 2012

Identification Of Root-Knot Nematode Species Occurring On Tomatoes In Kenya: Use Of Isozyme Phenotypes And Pcr-Rflp, Rael Birithia, Wanjohi Waceke, Peter Lomo, Daniel Masiga

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Root-knot nematodes (RKN) are serious pests of tomato production in Kenya. Accurate identification of the plant parasitic nematodes is important for their effective management. A study conducted to assess their prevalence and identify RKN occurring on tomatoes in Central Kenya showed infestation of the crop in all the three districts. Of the total sampled plants (N = 900), the RKN infestation level ranged from 28 to 62%. RKN disease severity ranged from 2.5 to 5.3 in all the locations. Meloidogyne incognita, M. javanica and M. arenaria were the only species found infesting tomatoes in these areas. Female nematodes sampled from …

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Oviposition Induced Volatile Emissions From African Smallholder Farmers' Maize Varieties, Amanuel Tamiru, Toby J.A. Bruce, Charles A.O. Midega, Christine M. Woodcock, Michael A. Birkett, John A. Pickett, Zeyaur R. Khan Mar 2012

Oviposition Induced Volatile Emissions From African Smallholder Farmers' Maize Varieties, Amanuel Tamiru, Toby J.A. Bruce, Charles A.O. Midega, Christine M. Woodcock, Michael A. Birkett, John A. Pickett, Zeyaur R. Khan

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Maize (corn), Zea mays, is a genetically diverse crop, and we have recently shown that certain open pollinated varieties (OPVs) of Latin American origin possess a trait not present in mainstream commercial varieties: they produce volatiles in response to stemborer oviposition that are attractive to stemborer parasitoids. Here, we tested whether a similar tritrophic effect occurs in the African OPVs 'Nyamula' and 'Jowi'. Herbivore induced plant volatiles (HIPVs) were collected from plants exposed to egg deposition by the stemborer Chilo partellus. In a four-arm olfactometer bioassay, the parasitic wasp Cotesia sesamiae preferred samples containing HIPVs from plants with eggs to …

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Management Of Alien Invasive Insect Pest Species And Diseases Of Fruits And Vegetables: Experiences From East Africa, B. Nyambo, S. Sevgan, A. Chabi-Olaye, S. Ekesi Oct 2011

Management Of Alien Invasive Insect Pest Species And Diseases Of Fruits And Vegetables: Experiences From East Africa, B. Nyambo, S. Sevgan, A. Chabi-Olaye, S. Ekesi

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The East African region is currently struggling to cope with several alien invasive insect pest species (AIS): the diamondback moth (DBM), fruit flies, Liriomyza leafminers, thrips and spider mites to name just a few. These insect pests have wide host range, are difficult to control with synthetic pesticides, and most are of quarantine status. AIS are becoming frequent pests in horticulture production systems, threat to food security, market access and rural livelihoods. The impact of these pests is aggravated by variability in climatic conditions, few taxonomic expertise for accurate and timely identification of new species, inadequate knowledge on viable alternative …

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Horticultural Pest Management And The African Economy: Successes, Challenges And Opportunities In A Changing Global Environment, S. Ekesi, A. Chabi-Olaye, S. Subramanian, C. Borgemeister Oct 2011

Horticultural Pest Management And The African Economy: Successes, Challenges And Opportunities In A Changing Global Environment, S. Ekesi, A. Chabi-Olaye, S. Subramanian, C. Borgemeister

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In many African countries, horticulture is the fastest growing agricultural sub-sector contributing significantly to national incomes. Diverse vegetables, fruits and spices are grown for domestic and export markets. Horticultural exports in Africa has increased by more than 50% in recent years and currently contributes >20% of agricultural exports by volume and income generation. Despite the growth, production has not kept pace with increasing demand due largely to biotic constraints attributed to arthropod pests. Agricultural research aimed at reducing insect pest damage can lead to increased horticultural production and improved rural livelihoods. icipe in collaboration with National Agricultural Research and Extension …

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Screenhouse Transmission Of Beauveria Bassiana From Infected To Non-Infected Adults Of Banana Weevil, C. A. Omukoko, J. M. Wesonga, E. M. Kahangi, L. S. Wamocho, K. N. Maniania Oct 2011

Screenhouse Transmission Of Beauveria Bassiana From Infected To Non-Infected Adults Of Banana Weevil, C. A. Omukoko, J. M. Wesonga, E. M. Kahangi, L. S. Wamocho, K. N. Maniania

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Laboratory studies have revealed great potential of entomopathogenic fungus Beauveria bassiana for use against the banana weevil, Cosmopolites sordidus, in banana. Adult banana weevils exposed to wet conidia of Beauveria bassiana suffered high mortalities ranging from 50-70% by 40 days post exposure when a concentration of 1×109 was used in the laboratory with three isolates ICIPE 273, M313 and M207 which were selected on the basis of high virulence against C. sordidus and high sporulation. However, impractical field delivery methods and high costs associated with the application of B. bassiana against C. sordidus prevent its use and commercialisation in banana …

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Duration Analysis Of Technology Adoption Effects Of Dissemination Pathways: A Case Of 'Push-Pull' Technology For Control Of Striga Weeds And Stemborers In Western Kenya, A. W. Murage, G. Obare, J. Chianu, D. M. Amudavi, J. Pickett, Z. R. Khan May 2011

Duration Analysis Of Technology Adoption Effects Of Dissemination Pathways: A Case Of 'Push-Pull' Technology For Control Of Striga Weeds And Stemborers In Western Kenya, A. W. Murage, G. Obare, J. Chianu, D. M. Amudavi, J. Pickett, Z. R. Khan

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Since its introduction, the 'push-pull' technology (PPT) has been promoted as an innovative approach for addressing yield losses caused by Striga weeds and stemborer infestations on farmers' maize fields in western Kenya. The technology has been disseminated through different pathways each of which might have different uptake enhancement capabilities. This study was concerned with how different dissemination pathways impacted on farmers' time to adoption while controlling the effects of selected socio-economic and regional factors. This assessment was necessary in order to recommend which dissemination pathway or combination of pathways that could provide an effective dissemination strategy that speed up adoption, …

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Spider Cognition, Robert R. Jackson, Fiona R. Cross Jan 2011

Spider Cognition, Robert R. Jackson, Fiona R. Cross

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Spiders, having minute brains, were once considered simple, instinct-driven automatons, but research on spider biology is revealing increasing evidence of their cognitive abilities. In this review, we discuss the complex, flexible behaviour of spiders, especially salticids, and highlight how sometimes the cognitive character of spider behaviour closely parallels that of much bigger animals. This includes the use of selective attention (both visual and olfactory) and the use of planned detours. The implications of these findings, and how they relate to bigger issues traditionally associated with big-brain animals, such as 'representation' and 'mind', are discussed. Also discussed are issues relating to …

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Isolation, Phylogeny And Evolution Of The Symrk Gene In The Legume Genus Lupinus L., Frédéric Mahé, Dragomira Markova, Rémy Pasquet, Marie Thérèse Misset, Abdelkader Aïnouche Jan 2011

Isolation, Phylogeny And Evolution Of The Symrk Gene In The Legume Genus Lupinus L., Frédéric Mahé, Dragomira Markova, Rémy Pasquet, Marie Thérèse Misset, Abdelkader Aïnouche

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SymRK is one of the key genes involved in initial steps of legume symbiotic association with fungi (mycorrhization) and nitrogen-fixing bacteria (nodulation). A large portion of the sequence encoding the extracellular domain of SYMRK was obtained for 38 lupine accessions and 2 outgroups in order to characterize this region, to evaluate its phylogenetic utility, and to examine whether its molecular evolutionary pattern is correlated with rhizobial diversity and specificity in Lupinus. The data suggested that, in Lupinus, SymRK is a single copy gene that shows good phylogenetic potential. Accordingly, SymRK provided additional support to previous molecular phylogenies, and shed additional …

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Construction Of A Ssr-Based Genetic Map And Identification Of Qtl For Domestication Traits Using Recombinant Inbred Lines From A Cross Between Wild And Cultivated Cowpea (V. Unguiculata (L.) Walp.), Mebeaselassie Andargie, Remy S. Pasquet, Bhavani S. Gowda, Geoffrey M. Muluvi, Michael P. Timko Jan 2011

Construction Of A Ssr-Based Genetic Map And Identification Of Qtl For Domestication Traits Using Recombinant Inbred Lines From A Cross Between Wild And Cultivated Cowpea (V. Unguiculata (L.) Walp.), Mebeaselassie Andargie, Remy S. Pasquet, Bhavani S. Gowda, Geoffrey M. Muluvi, Michael P. Timko

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Cowpea (Vigna unguiculata (L.) Walp.) is a grain legume commonly grown and consumed in many parts of the tropics and subtropics. A genetic linkage map was constructed using simple sequence repeat (SSR) markers and a recombinant inbred (RI) population of159 individuals derived from a cross between the breeding line 524B, a California Blackeye, and 219-01, a perennial wild cowpea from Kenya. Out of 912 primer combinations predicted to amplify SSRs in cowpea, 639 reliably produced amplification products in PCR assays and 202 (31.6%) were polymorphic between the two parents. These polymorphic SSRs were used to construct a genetic map consisting …

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Control Of Invasive Liriomyza Leafminer Species And Compliance With Food Safety Standards By Small Scale Snow Pea Farmers In Kenya, Zachary Maina Gitonga, Adenirin Chabi-Olaye, Dagmar Mithöfer, Julius Juma Okello, Cecilia Nyawira Ritho Dec 2010

Control Of Invasive Liriomyza Leafminer Species And Compliance With Food Safety Standards By Small Scale Snow Pea Farmers In Kenya, Zachary Maina Gitonga, Adenirin Chabi-Olaye, Dagmar Mithöfer, Julius Juma Okello, Cecilia Nyawira Ritho

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The Kenyan horticultural industry faces a new challenge following invasion by the quarantine Liriomyza leafminer species Liriomyza huidobrensis, Liriomyza sativae and Liriomyza trifolii which have recently become pests of economic importance. Controlling Liriomyza leafminers poses serious difficulties due to their biology and quarantine status. This paper examines farmers' awareness of the pests and difficulties faced in controlling them. (1) A questionnaire survey showed that snow pea farmers in Kenya rely mainly on pesticides for control of invasive Liriomyza leafminers; (2) Sixty five percent of respondents perceived pesticides to be ineffective; (3) As a result, 74% of respondents increased the frequency …

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Anopheles Larval Abundance And Diversity In Three Rice Agro-Village Complexes Mwea Irrigation Scheme, Central Kenya, Joseph M. Mwangangi, Josephat Shililu, Ephantus J. Muturi, Simon Muriu, Benjamin Jacob, Ephantus W. Kabiru, Charles M. Mbogo, John Githure, Robert J. Novak Aug 2010

Anopheles Larval Abundance And Diversity In Three Rice Agro-Village Complexes Mwea Irrigation Scheme, Central Kenya, Joseph M. Mwangangi, Josephat Shililu, Ephantus J. Muturi, Simon Muriu, Benjamin Jacob, Ephantus W. Kabiru, Charles M. Mbogo, John Githure, Robert J. Novak

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Background. The diversity and abundance of Anopheles larvae has significant influence on the resulting adult mosquito population and hence the dynamics of malaria transmission. Studies were conducted to examine larval habitat dynamics and ecological factors affecting survivorship of aquatic stages of malaria vectors in three agro-ecological settings in Mwea, Kenya. Methods. Three villages were selected based on rice husbandry and water management practices. Aquatic habitats in the 3 villages representing planned rice cultivation (Mbui Njeru), unplanned rice cultivation (Kiamachiri) and non-irrigated (Murinduko) agro-ecosystems were sampled every 2 weeks to generate stage-specific estimates of mosquito larval densities, relative abundance and diversity. …

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Geographic Distribution, Host Range And Perennation Of Cotesia Sesamiae And Cotesia Flavipes Cameron In Cultivated And Natural Habitats In Kenya, Duna Madu Mailafiya, Bruno Pierre Le Ru, Eunice Waitherero Kairu, Paul André Calatayud, Stéphane Dupas Jul 2010

Geographic Distribution, Host Range And Perennation Of Cotesia Sesamiae And Cotesia Flavipes Cameron In Cultivated And Natural Habitats In Kenya, Duna Madu Mailafiya, Bruno Pierre Le Ru, Eunice Waitherero Kairu, Paul André Calatayud, Stéphane Dupas

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Field surveys were carried out in four agroecological zones to assess the geographic distribution, host range and perennation of Cotesia sesamiae and Cotesia flavipes in cultivated and natural habitats in Kenya. The distribution of the two Cotesia species in different ecological regions was most affected by the suitability of the local stem borer species for parasitoid development, and temperature, as both species were found in localities dominated by their suitable host(s) where temperature favoured their occurrence. Fourteen years after its release, C. flavipes has maintained a high level of specificity to its target host Chilo partellus on maize and sorghum …

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Isoschaftoside, A C-Glycosylflavonoid From Desmodium Uncinatum Root Exudate, Is An Allelochemical Against The Development Of Striga, Antony M. Hooper, Muniru K. Tsanuo, Keith Chamberlain, Kay Tittcomb, Julie Scholes, Ahmed Hassanali, Zeyaur R. Khan, John A. Pickett Jun 2010

Isoschaftoside, A C-Glycosylflavonoid From Desmodium Uncinatum Root Exudate, Is An Allelochemical Against The Development Of Striga, Antony M. Hooper, Muniru K. Tsanuo, Keith Chamberlain, Kay Tittcomb, Julie Scholes, Ahmed Hassanali, Zeyaur R. Khan, John A. Pickett

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In East African small-holder farming of maize, the cattle forage legume, Desmodium uncinatum is used as an intercrop due to its allelopathic inhibition of parasitism by Striga hermonthica, an obligate parasitic weed that can devastate the maize crop. Bioassay-guided fractionation of the root extract of D. uncinatum revealed isoschaftoside to be the main compound in the most potent fraction inhibiting growth of germinated S. hermonthica radicles. Bioassays repeated with isoschaftoside isolated from a different plant source, Passiflora incarnata, proved it to be a biologically active component. Analysis of the root exudates produced by hydroponically grown D. uncinatum showed isoschaftoside to …

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Participatory Evaluation Of Integrated Pest And Soil Fertility Management Options Using Ordered Categorical Data Analysis, Hugo De Groote, Esther Rutto, George Odhiambo, Fred Kanampiu, Zeyaur Khan, Richard Coe, Bernard Vanlauwe Jun 2010

Participatory Evaluation Of Integrated Pest And Soil Fertility Management Options Using Ordered Categorical Data Analysis, Hugo De Groote, Esther Rutto, George Odhiambo, Fred Kanampiu, Zeyaur Khan, Richard Coe, Bernard Vanlauwe

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Maize is becoming the major food crop around Lake Victoria. Major constraints to its production are Striga, stem borer, and declining soil fertility. Innovative integrated technologies have been developed: the 'push-pull' system (intercropping with Desmodium and surrounded by Napier grass), soybean and Crotalaria rotations, and imidazolinone-resistant (IR) maize seed. In 12 demonstration trials in four villages in Siaya and Vihiga districts (Kenya) and two villages in Busia (Uganda) in 2003 and 2004, 504 farmers evaluated all cropping systems and a mono-cropped continuous maize, each cropped with IR or local maize, and supplemented or not with fertilizer, totaling 16 treatments. Farmers …

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Effect Of African Nightshade Species (Solanaceae) On Developmental Time And Life Table Parameters Of Tetranychus Evansi (Acari: Tetranychidae), Lucy Kananu Murungi, Aggrey Nyende, John Wesonga, Peter Masinde, Markus Knapp Mar 2010

Effect Of African Nightshade Species (Solanaceae) On Developmental Time And Life Table Parameters Of Tetranychus Evansi (Acari: Tetranychidae), Lucy Kananu Murungi, Aggrey Nyende, John Wesonga, Peter Masinde, Markus Knapp

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The effect of five African nightshade (Solanum sp.) species on the biological and demographic parameters of the tomato spider mite, Tetranychus evansi Baker and Pritchard, was examined in the laboratory at 25 ± 1°C, 70-80% RH and 12L:12D photoperiod. Duration of each development stage, reproduction rate, longevity, intrinsic rate of natural increase (rm), and doubling time (DT) of the tomato spider mite on the five nightshade species were calculated. The results indicated that S. villosum, S. scabrum, S. tarderemotum and S. americanum are more suitable for T. evansi due to a shorter developmental period, longer adult longevity, higher reproduction and …

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Proximity To A Forest Leads To Higher Honey Yield: Another Reason To Conserve, Susan O. Sande, Robin M. Crewe, Suresh K. Raina, Susan W. Nicolson, Ian Gordon Nov 2009

Proximity To A Forest Leads To Higher Honey Yield: Another Reason To Conserve, Susan O. Sande, Robin M. Crewe, Suresh K. Raina, Susan W. Nicolson, Ian Gordon

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Although tropical forest conservation is a top priority for human and environmental health, deforestation persists, mainly because of food and economic needs. No community will totally give up economic activities for the sake of ecological integrity, unless it is given alternative economic activities from which to draw its livelihood. Beekeeping in the forest buffer zone instead of traditional destructive honey-harvesting from forest trees is one such option at Arabuko Sokoke Forest (ASF) in Kenya. ASF is a dry coastal forest which is home to endangered and threatened fauna and is a hotspot considered a priority for conservation. In order to …

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Integration Of Edible Beans (Phaseolus Vulgaris L.) Into The Push-Pull Technology Developed For Stemborer And Striga Control In Maize-Based Cropping Systems, Zeyaur R. Khan, Charles A.O. Midega, Japhether M. Wanyama, David M. Amudavi, Ahmed Hassanali, Jimmy Pittchar, John A. Pickett Nov 2009

Integration Of Edible Beans (Phaseolus Vulgaris L.) Into The Push-Pull Technology Developed For Stemborer And Striga Control In Maize-Based Cropping Systems, Zeyaur R. Khan, Charles A.O. Midega, Japhether M. Wanyama, David M. Amudavi, Ahmed Hassanali, Jimmy Pittchar, John A. Pickett

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Smallholder farming systems in eastern Africa are characterized by cereal/edible legume intercrops in fields severely constrained by parasitic weed, Striga hermonthica, cereal stemborers and declining soil fertility. The push-pull technology concurrently addresses these constraints. It involves intercropping maize with stemborer repellent fodder legume, Desmodium spp. (push), with an attractant crop, Napier grass, Pennisetum purpureum (pull), planted around this intercrop, thus making it difficult to interplant edible legumes. We assessed farmers' practice and perceptions on intercropping and willingness to integrate beans in their push-pull plots from a sample of 300 farmers in six districts in western Kenya. All the respondents traditionally …

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White Lupin Leads To Increased Maize Yield Through A Soil Fertility-Independent Mechanism: A New Candidate For Fighting Striga Hermonthica Infestation?, Laure Weisskopf, Pollycarp Akello, Roxane Milleret, Zeyaur R. Khan, Fritz Schulthess, Jean Michel Gobat, Renée Claire Le Bayon Jun 2009

White Lupin Leads To Increased Maize Yield Through A Soil Fertility-Independent Mechanism: A New Candidate For Fighting Striga Hermonthica Infestation?, Laure Weisskopf, Pollycarp Akello, Roxane Milleret, Zeyaur R. Khan, Fritz Schulthess, Jean Michel Gobat, Renée Claire Le Bayon

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Nitrogen (N)-deficiency and lack of phosphorus (P) availability are major constraints to maize yields in Western Kenya. In a two-season field study in the lake Victoria basin, we tested the capacity of white lupin (Lupinus albus (L.), cv. Ultra), as a nitrogen-fixing crop with a highly efficient P-acquisition capacity, to increase maize yields when used as a companion or cover crop, or as a source of organic matter. Each experiment was performed on three different fields (Vertisols) differing in N/P availability, previous cropping history and in levels of infestation by the parasitic weed Striga hermonthica (Del.) Benth. Our results show …

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Diversity, Distribution And Role Of Wild Crucifers In Major Cabbage And Kale Growing Areas Of Kenya, R. Kahuthia-Gathu, B. Löhr, H. M. Poehling, P. K. Mbugua Jun 2009

Diversity, Distribution And Role Of Wild Crucifers In Major Cabbage And Kale Growing Areas Of Kenya, R. Kahuthia-Gathu, B. Löhr, H. M. Poehling, P. K. Mbugua

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An investigation of the diversity and distribution of wild crucifer species and their importance for cultivated crucifers was conducted during 2005 and 2006 in the highland and mid-altitude semi-arid areas of Kenya. Thirteen species of wild crucifers in nine genera were recorded: Raphanus raphanistrum, Erucastrum arabicum, Sisymbrium officinale, Crambe kilimandscharica, Capsella bursa-pastoris, Rorippa nudiuscula, Ro. micrantha, Ro. microphylla, Lepidium bonariense, Coronopus didymus, Brassica rapa, B. juncea and an unidentified Brassica species. Highland areas had significantly higher species diversity and species richness than mid-altitude semi-arid areas. Species richness, diversity and evenness varied with season and location. Raphanus raphanistrum was the dominant …

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