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Articles 751 - 780 of 1443

Full-Text Articles in Life Sciences

Rice Volatiles Lure Gravid Malaria Mosquitoes, Anopheles Arabiensis, Betelehem Wondwosen, Göran Birgersson, Emiru Seyoum, Habte Tekie, Baldwyn Torto, Ulrike Fillinger, Sharon R. Hill, Rickard Ignell Nov 2016

Rice Volatiles Lure Gravid Malaria Mosquitoes, Anopheles Arabiensis, Betelehem Wondwosen, Göran Birgersson, Emiru Seyoum, Habte Tekie, Baldwyn Torto, Ulrike Fillinger, Sharon R. Hill, Rickard Ignell

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Mosquito oviposition site selection is essential for vector population dynamics and malaria epidemiology. Irrigated rice cultivations provide ideal larval habitats for malaria mosquitoes, which has resulted in increased prevalence of the malaria vector, Anopheles arabiensis, in sub-Saharan Africa. The nature and origin of the cues regulating this behaviour are only now being elucidated. We show that gravid Anopheles arabiensis are attracted and oviposit in response to the odour present in the air surrounding rice. Furthermore, we identify a synthetic rice odour blend, using electrophysiological and chemical analyses, which elicits attraction and oviposition in laboratory assays, as well as attraction of …

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Spatial And Temporal Spread Of Maize Stem Borer Busseola Fusca (Fuller) (Lepidoptera: Noctuidae) Damage In Smallholder Farms, Frank T. Ndjomatchoua, Henri E.Z. Tonnang, Christophe Plantamp, Pascal Campagne, Clément Tchawoua, Bruno P. Le Ru Nov 2016

Spatial And Temporal Spread Of Maize Stem Borer Busseola Fusca (Fuller) (Lepidoptera: Noctuidae) Damage In Smallholder Farms, Frank T. Ndjomatchoua, Henri E.Z. Tonnang, Christophe Plantamp, Pascal Campagne, Clément Tchawoua, Bruno P. Le Ru

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The main purpose of this study was to understand the spatio-temporal spread of the maize stem borer Busseola fusca (Fuller) (Lepidoptera: Noctuidae) in smallholder maize farms. The analysis carried out allowed the establishment of complementary sampling scheme and analysis that can be applied to investigate the propagation of stem borer damages and extended to other insect pests. This approach requires consideration of all plants point locations, the knowledge on the level of damage and its characterization. Results showed that there was a two-week interval between occurrence of the peaks of leaf damage and male adult moth abundance. The prior role …

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Productivity, Profitability And Partial Nutrient Balance In Maize-Based Conventional And Organic Farming Systems In Kenya, Noah Adamtey, Martha W. Musyoka, Christine Zundel, Juan Guillermo Cobo, Edward Karanja, Komi K.M. Fiaboe, Anne Muriuki, Monicah Mucheru-Muna, Bernard Vanlauwe, Estelle Berset, Monika M. Messmer, Andreas Gattinger, Gurbir S. Bhullar, Georg Cadisch, Andreas Fliessbach, Paul Mäder, Urs Niggli, Dionys Foster Nov 2016

Productivity, Profitability And Partial Nutrient Balance In Maize-Based Conventional And Organic Farming Systems In Kenya, Noah Adamtey, Martha W. Musyoka, Christine Zundel, Juan Guillermo Cobo, Edward Karanja, Komi K.M. Fiaboe, Anne Muriuki, Monicah Mucheru-Muna, Bernard Vanlauwe, Estelle Berset, Monika M. Messmer, Andreas Gattinger, Gurbir S. Bhullar, Georg Cadisch, Andreas Fliessbach, Paul Mäder, Urs Niggli, Dionys Foster

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In 2007 two long-term trials were established in Kenya to contribute research-based evidence to the global debate on the productivity, economic viability and sustainability of different agricultural production systems. These trials compare conventional (Conv) and organic (Org) farming systems at high and low input levels at two locations, i.e. Chuka, with Humic Nitisols, high inherent soil fertility and rainfall, and Thika, with Rhodic Nitisols with low soil fertility and rainfall. The high input systems (High) represent commercial-scale, export-oriented production that uses the recommended amounts of fertilisers, pesticides and irrigation water to generate high yields, whilst the low input systems (Low) …

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Effect Of Triple-Layer Hermetic Bagging On Mould Infection And Aflatoxin Contamination Of Maize During Multi-Month On-Farm Storage In Kenya, J. Ng'ang'a, C. Mutungi, S. Imathiu, H. Affognon Oct 2016

Effect Of Triple-Layer Hermetic Bagging On Mould Infection And Aflatoxin Contamination Of Maize During Multi-Month On-Farm Storage In Kenya, J. Ng'ang'a, C. Mutungi, S. Imathiu, H. Affognon

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Field trials were conducted in small-scale farmers' grain stores in an aflatoxin endemic region to assess the effect of storing maize in triple layer hermetic (PICS™) bags on aflatoxin contamination. Shelled maize grain was purchased from farmers, and filled into PICS bags, woven polypropylene (PP) and jute bags and kept in the farmers' own stores for 35 weeks. Grain moisture content, total mould count and mould incidence levels were examined at onset and after every 7 weeks during the 35 weeks of storage. Aflatoxin contamination was examined at onset, and after 14, 28 and 35 weeks. Ambient temperature and r.h. …

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Frequency And Time Pattern Differences In Acoustic Signals Produced By Prostephanus Truncatus (Horn) (Coleoptera: Bostrichidae) And Sitophilus Zeamais (Motschulsky) (Coleoptera: Curculionidae) In Stored Maize, A. W. Njoroge, H. Affognon, C. Mutungi, B. Rohde, U. Richter, O. Hensel, R. W. Mankin Oct 2016

Frequency And Time Pattern Differences In Acoustic Signals Produced By Prostephanus Truncatus (Horn) (Coleoptera: Bostrichidae) And Sitophilus Zeamais (Motschulsky) (Coleoptera: Curculionidae) In Stored Maize, A. W. Njoroge, H. Affognon, C. Mutungi, B. Rohde, U. Richter, O. Hensel, R. W. Mankin

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Frequency spectra and timing patterns of brief, 1-10 ms broadband sound impulses produced by movement and feeding activities of Prostephanus truncatus and Sitophilus zeamais last instars and adults in maize were investigated to find spectral and temporal pattern information useful for distinguishing among these species and stages. The impulse spectra were categorized into five different types of frequency patterns (profiles), designated Broadband, HighF, MidF1, MidF2 and LowF to indicate differences in their peak energies and broadness of frequency range. Groups (trains) of three or more closely spaced impulses, termed bursts, were observed to occur frequently in all recordings, as has …

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Description Of New Ceratitis Species (Diptera: Tephritidae) From Africa, Or How Morphological And Dna Data Are Complementary In Discovering Unknown Species And Matching Sexes, Marc De Meyer, Maulid Mwatawala, Robert S. Copeland, Massimiliano Virgilio Sep 2016

Description Of New Ceratitis Species (Diptera: Tephritidae) From Africa, Or How Morphological And Dna Data Are Complementary In Discovering Unknown Species And Matching Sexes, Marc De Meyer, Maulid Mwatawala, Robert S. Copeland, Massimiliano Virgilio

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This paper describes five new Ceratitis species from the eastern and southern parts of the Afrotropical Region: C. (Pterandrus) quilicii De Meyer, Mwatawala & Virgilio sp. nov.; C. (Ceratalaspis) pallidula De Meyer, Mwatawala & Virgilio sp. nov.; C. (Ceratalaspis) taitaensis De Meyer & Copeland sp. nov.; C. (Ceratalaspis) sawahilensis De Meyer & Virgilio sp. nov.; and C. (Ceratalaspis) flavipennata De Meyer & Virgilio sp. nov. Their relationships with closely allied species within their respective subgenera are discussed where appropriate, and diagnostic characters are given. DNA barcodes are provided for all new species. In addition, the hitherto unknown male of C. …

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Farmers' Knowledge And Perception Of Grain Legume Pests And Their Management In The Eastern Province Of Kenya, Andnet Abtew, Saliou Niassy, Hippolyte Affognon, Sevgan Subramanian, Serge Kreiter, Giovanna Tropea Garzia, Thibaud Martin Sep 2016

Farmers' Knowledge And Perception Of Grain Legume Pests And Their Management In The Eastern Province Of Kenya, Andnet Abtew, Saliou Niassy, Hippolyte Affognon, Sevgan Subramanian, Serge Kreiter, Giovanna Tropea Garzia, Thibaud Martin

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Grain legumes play an important role in community livelihood and in the national economy in Kenya. Unfortunately, in many African countries, production doesn't satisfy the demand in grains due to various constrains. Understanding farmers practices and behavior in the management of grain legume pests is a crucial step in the development of sustainable management strategies. A total of 216 farmers were surveyed in eight districts of eastern Kenya to evaluate farmers' knowledge and perceptions of grain legume pests; to examine current pest management practices, and to identify other production constraints. Grain legumes are grown by a wide age-group of farmers, …

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Survey Of Nematodes Associated With Terrestrial Slugs In Norway, J. L. Ross, E. S. Ivanova, B. A. Hatteland, M. B. Brurberg, S. Haukeland Sep 2016

Survey Of Nematodes Associated With Terrestrial Slugs In Norway, J. L. Ross, E. S. Ivanova, B. A. Hatteland, M. B. Brurberg, S. Haukeland

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A survey of nematodes associated with terrestrial slugs was conducted for the first time in Norway. A total of 611 terrestrial slugs were collected from 32 sample sites. Slugs were identified by means of morphological examination, dissection of genitalia and molecular analysis using mitochondrial DNA. Twelve slug species were identified, representing four different slug families. Internal nematodes were identiï¬'d by means of morphological analysis and the sequencing of the 18S rRNA gene. Of the sample sites studied, 62.5% were found to be positive for nematode parasites, with 18.7% of all slugs discovered being infected. Five nematode species were identified in …

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Effects Of Entomopathogenic Fungus Metarhizium Anisopliae On Non-Target Ants Associated With Odontotermes Spp. (Isoptera: Termitidae) Termite Mounds In Kenya, E. A. Abonyo, N. K. Maniania, C. M. Warui, E. D. Kokwaro, T. M. Palmer, D. F. Doak, A. K. Brody Sep 2016

Effects Of Entomopathogenic Fungus Metarhizium Anisopliae On Non-Target Ants Associated With Odontotermes Spp. (Isoptera: Termitidae) Termite Mounds In Kenya, E. A. Abonyo, N. K. Maniania, C. M. Warui, E. D. Kokwaro, T. M. Palmer, D. F. Doak, A. K. Brody

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Termites are an important component of savannah ecosystems throughout Africa. Despite their importance in the ecosystem, they can be serious pests of structures, houses, rangelands, tropical forestry, and agriculture. For many decades, chemical insecticides have remained popular for termite management worldwide. However, with the growing environmental concerns over pesticides, biological control using entomopathogenic fungi such as Metarhizium anisopliae (Metschnikoff) Sorokin has become an often-considered alternative. Metarhizium anisopliae is an ubiquitous, naturally occurring pathogen, which has been reported infecting over 200 insect species; therefore, there is concern that use of M. anisopliae may affect non-target organisms. The effects of M. anisopliae …

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Chemical Parameters And Bacterial Communities Associated With Larval Habitats Of Anopheles, Culex And Aedes Mosquitoes (Diptera: Culicidae) In Western Kenya, Thomas Ogao Onchuru, Yvonne Ukamaka Ajamma, Marion Burugu, Martin Kaltenpoth, Daniel Masiga, Jandouwe Villinger Sep 2016

Chemical Parameters And Bacterial Communities Associated With Larval Habitats Of Anopheles, Culex And Aedes Mosquitoes (Diptera: Culicidae) In Western Kenya, Thomas Ogao Onchuru, Yvonne Ukamaka Ajamma, Marion Burugu, Martin Kaltenpoth, Daniel Masiga, Jandouwe Villinger

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Aquatic larval habitat conditions influence the development, fitness and vectorial capacity of mosquitoes. In turn, human activities can influence these conditions and shape mosquito vector distribution, thus affecting pathogen circulation and transmission. We measured environmental factors (chemical and microbial) in mosquito larval habitats and evaluated their potential as predictors for the occurrence of different mosquito species in an arbovirus and malaria endemic region of western Kenya.We found significantly greater proportions of Aedes aegypti mosquito larvae in ammonium and phosphate rich habitats, suggesting that fertilizer usage could potentially increase aquatic habitat suitability and Aedes vectored disease transmission. Anopheles gambiae larval habitats …

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Developmental Biology And Demographic Parameters Of Antestia Bug Antestiopsis Thunbergii (Hemiptera: Pentatomidae), On Coffea Arabica (Rubiaceae) At Different Constant Temperatures, Abdelmutalab Gesmalla Ahmed, Lucy Kananu Murungi, Regis Babin Sep 2016

Developmental Biology And Demographic Parameters Of Antestia Bug Antestiopsis Thunbergii (Hemiptera: Pentatomidae), On Coffea Arabica (Rubiaceae) At Different Constant Temperatures, Abdelmutalab Gesmalla Ahmed, Lucy Kananu Murungi, Regis Babin

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The antestia bug Antestiopsis thunbergii (Gmelin 1790) is a major coffee pest in East Africa. Nymphs and adults feed on all vegetative and fruiting parts of the coffee tree leading to yield reduction and poor quality of coffee beans. Our study aimed to characterize the developmental biology and provide life table parameters for A. thunbergii reared in the laboratory. The biology of A. thunbergii was studied at four constant temperatures of 20, 25, 30 and 35°C with 80±5% RH and a photoperiod of L:D 12:12. Complete development of A. thunbergii from egg to adult occurred between 20 and 30°C, while …

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First Record Of Tuta Absoluta (Lepidoptera: Gelechiidae) In Uganda, Venansio Tumuhaise, Fathiya M. Khamis, Ambrose Agona, Godfrey Sseruwu, Samira A. Mohamed Sep 2016

First Record Of Tuta Absoluta (Lepidoptera: Gelechiidae) In Uganda, Venansio Tumuhaise, Fathiya M. Khamis, Ambrose Agona, Godfrey Sseruwu, Samira A. Mohamed

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An invasive pest, Tuta absoluta (Meyrick) has been observed infesting tomato Solanum lycopersicum L. (Solanales: Solanaceae) in Central Uganda. The affected farmer made the report, and upon visiting the farm, we observed tiny larvae, green to cream in colour with a black head feeding on tomato leaves, fruit, as well as tender stems. Also, we saw several tiny moths resting on screen house linings. Delta traps baited with TUA-Optima® (Russell IPM) were set in and around the affected farm. Dozens of moths were attracted and trapped on the sticky surface of the traps. The team tentatively identified the insect as …

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Assessing The Long-Term Welfare Effects Of The Biological Control Of Cereal Stemborer Pests In East And Southern Africa: Evidence From Kenya, Mozambique And Zambia, Soul Kifouly G. Midingoyi, Hippolyte D. Affognon, Ibrahim Macharia, Georges Ong'amo, Esther Abonyo, Gerphas Ogola, Hugo De Groote, Bruno Leru Aug 2016

Assessing The Long-Term Welfare Effects Of The Biological Control Of Cereal Stemborer Pests In East And Southern Africa: Evidence From Kenya, Mozambique And Zambia, Soul Kifouly G. Midingoyi, Hippolyte D. Affognon, Ibrahim Macharia, Georges Ong'amo, Esther Abonyo, Gerphas Ogola, Hugo De Groote, Bruno Leru

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The International Centre of Insect Physiology and Ecology (icipe), undertook a biological control (BC) programme for control of stemborers from 1993 to 2008, to reduce cereal yield losses due to stemborer attack in East and Southern Africa. The programme released four biological control agents-the larval parasitoids Cotesia flavipes and Cotesia sesamiae, the egg parasitoid Telenomus isis and the pupal parasitoid Xanthopimpla stemmator-to control the economically important stemborer pests Busseola fusca, Chilo partellus and Sesamia calamistis. Two of the natural enemies that were released got established and spread to many localities in the region. This study adopted the economic surplus model …

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Application Of Superabsorbent Polymers (Sap) As Desiccants To Dry Maize And Reduce Aflatoxin Contamination, Duncan O. Mbuge, Renata Negrini, Livine O. Nyakundi, Serge P. Kuate, Ranajit Bandyopadhyay, William M. Muiru, Baldwyn Torto, Raffaele Mezzenga Aug 2016

Application Of Superabsorbent Polymers (Sap) As Desiccants To Dry Maize And Reduce Aflatoxin Contamination, Duncan O. Mbuge, Renata Negrini, Livine O. Nyakundi, Serge P. Kuate, Ranajit Bandyopadhyay, William M. Muiru, Baldwyn Torto, Raffaele Mezzenga

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The ability of superabsorbent polymers (SAP) in drying maize and controlling aflatoxin contamination was studied under different temperatures, drying times and SAP-to-maize ratios. Temperature and drying time showed significant influence on the aflatoxin formation. SAP-to-maize ratios between 1:1 and 1:5 showed little or no aflatoxin contamination after drying to the optimal moisture content (MC) of 13 %, while for ratios 1:10 and 1:20, aflatoxin contamination was not well controlled due to the overall higher MC and drying time, which made these ratios unsuitable for the drying process. Results clearly show that temperature, frequency of SAP change, drying time and SAP-to-maize …

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Understanding Variability In Crop Response To Fertilizer And Amendments In Sub-Saharan Africa, Job Kihara, Generose Nziguheba, Shamie Zingore, Adama Coulibaly, Anthony Esilaba, Vernon Kabambe, Samuel Njoroge, Cheryl Palm, Jeroen Huising Aug 2016

Understanding Variability In Crop Response To Fertilizer And Amendments In Sub-Saharan Africa, Job Kihara, Generose Nziguheba, Shamie Zingore, Adama Coulibaly, Anthony Esilaba, Vernon Kabambe, Samuel Njoroge, Cheryl Palm, Jeroen Huising

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Improved understanding of soil fertility factors limiting crop productivity is important to develop appropriate soil and nutrient management recommendations in sub-Saharan Africa. Diagnostic trials were implemented in Kenya, Malawi, Mali, Nigeria and Tanzania, as part of the African Soils Information Service (AfSIS) project, to identify soil fertility constraints to crop production across various cropping systems and soil fertility conditions. In each country, one to three sites of 10 km × 10 km were included with each site having 12-31 field trials. The treatments tested included a control, an NPK treatment, three treatments in which the N, P and K nutrients …

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Prospects For Repellent In Pest Control: Current Developments And Future Challenges, Emilie Deletre, Bertrand Schatz, Denis Bourguet, Fabrice Chandre, Livy Williams, Alain Ratnadass, Thibaud Martin Aug 2016

Prospects For Repellent In Pest Control: Current Developments And Future Challenges, Emilie Deletre, Bertrand Schatz, Denis Bourguet, Fabrice Chandre, Livy Williams, Alain Ratnadass, Thibaud Martin

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The overall interest in environmentally safe pest control methods and the rise of insecticide resistance in pest populations have prompted medical and agricultural entomology research on insect repellents in recent years. However, conducting research on repellent is challenging for several reasons: (1) the different repellent phenomena are not well defined; (2) it is difficult to test for and quantify repellent; (3) the physiological mechanisms are poorly known; (4) the field efficacy appears to be highly variable. Here, we identified five different types of repellent: expellency, irritancy, deterrency, odor masking and visual masking, and described behavioral bioassays to differentiate between them. …

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Opposing Roles Of Foliar And Glandular Trichome Volatile Components In Cultivated Nightshade Interaction With A Specialist Herbivore, Lucy Kananu Murungi, Hillary Kirwa, Daisy Salifu, Baldwyn Torto Aug 2016

Opposing Roles Of Foliar And Glandular Trichome Volatile Components In Cultivated Nightshade Interaction With A Specialist Herbivore, Lucy Kananu Murungi, Hillary Kirwa, Daisy Salifu, Baldwyn Torto

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Plant chemistry is an important contributor to the interaction with herbivores. Here, we report on a previously unknown role for foliar and glandular trichome volatiles in their interaction with the specialist herbivore of solanaceous plants, the tomato red spider mite Tetranychus evansi.We used various bioassays and chemical analyses including coupled gas chromatography- mass spectrometry (GC/MS) and liquid chromatography coupled to quadrupole time of flight mass spectrometry (LC-QToF-MS) to investigate this interaction between cultivated African nightshades and T. evansi.We show that, whereas morphologically different cultivated African nightshade species released similar foliar volatile organic compounds (VOCs) that attracted T. evansi, VOCs released …

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Storage Of Pigeonpea Grain (Cajanus Cajan (L.) Millsp.) In Hermetic Triple-Layer Bags Prevents Losses Caused By Callosobruchus Maculatus (F.) (Coleoptera: Bruchidae), H. D. Affognon, A. W. Njoroge, C. M. Mutungi, J. Manono, D. Baributsa, L. L. Murdock Jul 2016

Storage Of Pigeonpea Grain (Cajanus Cajan (L.) Millsp.) In Hermetic Triple-Layer Bags Prevents Losses Caused By Callosobruchus Maculatus (F.) (Coleoptera: Bruchidae), H. D. Affognon, A. W. Njoroge, C. M. Mutungi, J. Manono, D. Baributsa, L. L. Murdock

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Dry pigeonpea grain is susceptible to infestation from the cowpea bruchid during storage. This study investigated the potential of Purdue Improved Cowpea Storage (PICS™) and polypropylene (PP) bags for reducing insect infestation under ambient laboratory conditions for six months. Some of the bags were artificially infested with cowpea bruchid Callosobruchus maculatus (PICS1, PP1) while others were not (PICS0, PP0). In an additional trial, PP bags containing pigeonpeas were treated with Actellic Super® dust before being artificially infested (PP1Ac). Moisture content, number of live C. maculatus adults, grain damage, and weight loss were determined at monthly intervals. Temperature and relative humidity …

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Redescription Of Helorus Ruficornis Förster (Hymenoptera: Heloridae), With A New Synonymy And New Afrotropical Specimen Records, Matthew L. Buffington, Robert S. Copeland Jul 2016

Redescription Of Helorus Ruficornis Förster (Hymenoptera: Heloridae), With A New Synonymy And New Afrotropical Specimen Records, Matthew L. Buffington, Robert S. Copeland

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Research up to this point has recorded two species of Afrotropical Heloridae: Helorus ruficornis Förster and H. elgoni Risbec. After examining recently collected specimens from Kenya and Burundi, we have been able to better understand intraspecific variation within Helorus ruficornis, and as a result, we hereby synonymize H. elgoni with H. ruficornis, redescribe H. ruficornis, and illustrate the holotype of H. elgoni for the first time. We also discuss new collection records for Afrotropical Heloridae, as well as possible habitat preferences.

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An Indirect Defence Trait Mediated Through Egg-Induced Maize Volatiles From Neighbouring Plants, Daniel M. Mutyambai, Toby J.A. Bruce, Johnnie Van Den Berg, Charles A.O. Midega, John A. Pickett, Zeyaur R. Khan Jul 2016

An Indirect Defence Trait Mediated Through Egg-Induced Maize Volatiles From Neighbouring Plants, Daniel M. Mutyambai, Toby J.A. Bruce, Johnnie Van Den Berg, Charles A.O. Midega, John A. Pickett, Zeyaur R. Khan

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Attack of plants by herbivorous arthropods may result in considerable changes to the plant's chemical phenotype with respect to emission of herbivore-induced plant volatiles (HIPVs). These HIPVs have been shown to act as repellents to the attacking insects as well as attractants for the insects antagonistic to these herbivores. Plants can also respond to HIPV signals from other plants that warn them of impending attack. Recent investigations have shown that certain maize varieties are able to emit volatiles following stemborer egg deposition. These volatiles attract the herbivore's parasitoids and directly deter further oviposition. However, it was not known whether these …

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Push-Pull: Chemical Ecology-Based Integrated Pest Management Technology, Zeyaur Khan, Charles A.O. Midega, Antony Hooper, John Pickett Jul 2016

Push-Pull: Chemical Ecology-Based Integrated Pest Management Technology, Zeyaur Khan, Charles A.O. Midega, Antony Hooper, John Pickett

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Lepidopterous stemborers, and parasitic striga weeds belonging to the family Orobanchaceae, attack cereal crops in sub-Saharan Africa causing severe yield losses. The smallholder farmers are resource constrained and unable to afford expensive chemicals for crop protection. The push–pull technology, a chemical ecology- based cropping system, is developed for integrated pest and weed management in cereal–livestock farming systems. Appropriate plants were selected that naturally emit signaling chemicals (semiochemicals). Plants highly attractive for stemborer egg laying were selected and employed as trap crops (pull), to draw pests away from the main crop. Plants that repelled stemborer females were selected as intercrops (push). …

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Maize Response To Macronutrients And Potential For Profitability In Sub-Saharan Africa, J. Kihara, J. Huising, G. Nziguheba, B. S. Waswa, S. Njoroge, V. Kabambe, E. Iwuafor, C. Kibunja, A. O. Esilaba, A. Coulibaly Jul 2016

Maize Response To Macronutrients And Potential For Profitability In Sub-Saharan Africa, J. Kihara, J. Huising, G. Nziguheba, B. S. Waswa, S. Njoroge, V. Kabambe, E. Iwuafor, C. Kibunja, A. O. Esilaba, A. Coulibaly

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Sub-Saharan Africa (SSA) is plagued by low productivity and little research is available on the attainable responses and profitability to applied nutrients under variable environments. The objective of this study was to determine the attainable maize grain response to and potential of profitability of N, P and K application in SSA using boundary line approaches. Data from experiments conducted in SSA under AfSIS project (2009–2012) and from FAO trials database (1969–1996) in 15 countries and constituting over 375 different experimental locations and 6600 data points are used. Both response to fertilizer and value cost ratio (VCR) are highly variable and …

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Vector Competence Of Aedes Aegypti In Transmitting Chikungunya Virus: Effects And Implications Of Extrinsic Incubation Temperature On Dissemination And Infection Rates, Sophiah Mbaika, Joel Lutomiah, Edith Chepkorir, Francis Mulwa, Christopher Khayeka-Wandabwa, Caroline Tigoi, Elijah Oyoo-Okoth, James Mutisya, Zipporah Ng'ang'a, Rosemary Sang Jun 2016

Vector Competence Of Aedes Aegypti In Transmitting Chikungunya Virus: Effects And Implications Of Extrinsic Incubation Temperature On Dissemination And Infection Rates, Sophiah Mbaika, Joel Lutomiah, Edith Chepkorir, Francis Mulwa, Christopher Khayeka-Wandabwa, Caroline Tigoi, Elijah Oyoo-Okoth, James Mutisya, Zipporah Ng'ang'a, Rosemary Sang

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Background: Aedes aegypti is a competent arthropod vector of chikungunya virus (CHIKV). The rate at which the virus disseminate in the vector is limited by temperature of their environment which can be an important determinant of geographical and seasonal limits to transmission by the arthropods in the tropics. This study investigated the vector competence of Ae. aegypti for CHIKV at ambient temperature of 32 and 26 °C (Coastal and Western Kenya respectively) reared at Extrinsic Incubation Temperature (EIT) of 32 and 26 °C that resembles those in the two regions. Methods: Ae. aegypti eggs were collected from coastal and Western …

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Low Permeability Triple-Layer Plastic Bags Prevent Losses Of Maize Caused By Insects In Rural On-Farm Stores, Jeremiah Ng’Ang’A, Christopher Mutungi, Samuel M. Imathiu, Hippolyte Affognon Jun 2016

Low Permeability Triple-Layer Plastic Bags Prevent Losses Of Maize Caused By Insects In Rural On-Farm Stores, Jeremiah Ng’Ang’A, Christopher Mutungi, Samuel M. Imathiu, Hippolyte Affognon

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Participatory on-farm trials were conducted to assess effectiveness of Purdue Improved Crop Storage (PICS™) bags for storage of maize in small-scale farmers’ stores in rural villages in eastern Kenya. A PICS bag is a three-layered hermetic bag-system that forms a barrier against the influx of oxygen and the escape of carbon dioxide. Jute, woven polypropylene or PICS bags were filled with shelled maize grain, purchased from the participating farmers, and the three sets of bags kept in the farmers’ own stores for 35 weeks. Oxygen and carbon dioxide levels in the PICS bags were monitored, as well as the temperature …

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Sustainable Intensification Of Agricultural Systems In The Central African Highlands: The Need For Institutional Innovation, Marc Schut, Piet Van Asten, Chris Okafor, Cyrille Hicintuka, Sylvain Mapatano, Nsharwasi Léon Nabahungu, Desire Kagabo, Perez Muchunguzi, Emmanuel Njukwe, Paul M. Dontsop-Nguezet, Murat Sartas, Bernard Vanlauwe Jun 2016

Sustainable Intensification Of Agricultural Systems In The Central African Highlands: The Need For Institutional Innovation, Marc Schut, Piet Van Asten, Chris Okafor, Cyrille Hicintuka, Sylvain Mapatano, Nsharwasi Léon Nabahungu, Desire Kagabo, Perez Muchunguzi, Emmanuel Njukwe, Paul M. Dontsop-Nguezet, Murat Sartas, Bernard Vanlauwe

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This study identifies entry points for innovation for sustainable intensification of agricultural systems. An agricultural innovation systems approach is used to provide a holistic image of (relations between) constraints faced by different stakeholder groups, the dimensions and causes of these constraints, and intervention levels, timeframes and types of innovations needed. Our data shows that constraints for sustainable intensification of agricultural systems are mainly of economic and institutional nature. Constraints are caused by the absence, or poor functioning of institutions such as policies and markets, limited capabilities and financial resources, and ineffective interaction and collaboration between stakeholders. Addressing these constraints would …

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Molecular Identification Of Different Trypanosome Species And Subspecies In Tsetse Flies Of Northern Nigeria, Clement Isaac, Marc Ciosi, Alana Hamilton, Kathleen Maria Scullion, Peter Dede, Igho Benjamin Igbinosa, Oyebiguwa Patrick Goddey Nmorsi, Dan Masiga, C. Michael R. Turner May 2016

Molecular Identification Of Different Trypanosome Species And Subspecies In Tsetse Flies Of Northern Nigeria, Clement Isaac, Marc Ciosi, Alana Hamilton, Kathleen Maria Scullion, Peter Dede, Igho Benjamin Igbinosa, Oyebiguwa Patrick Goddey Nmorsi, Dan Masiga, C. Michael R. Turner

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Background: Animal African Trypanosomiasis (AAT) is caused by several species of trypanosomes including Trypanosoma congolense, T. vivax, T. godfreyi, T. simiae and T. brucei. Two of the subspecies of T. brucei also cause Human African Trypanosomiasis. Although some of them can be mechanically transmitted by biting flies; these trypanosomes are all transmitted by tsetse flies which are the cyclical vectors of Trypanosoma congolense, T. godfreyi, T. simiae and T. brucei. We present here the first report assessing the prevalence of trypanosomes in tsetse flies in Nigeria using molecular tools. Methods: 488 tsetse flies of three species, Glossina palpalis palpalis, G. …

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Can Climate-Driven Change Influence Silicon Assimilation By Cereals And Hence The Distribution Of Lepidopteran Stem Borers In East Africa?, P. A. Calatayud, E. Njuguna, S. Mwalusepo, M. Gathara, G. Okuku, A. Kibe, B. Musyoka, D. Williamson, G. Ong'amo, G. Juma, T. Johansson, S. Subramanian, E. Gatebe, B. Le Ru May 2016

Can Climate-Driven Change Influence Silicon Assimilation By Cereals And Hence The Distribution Of Lepidopteran Stem Borers In East Africa?, P. A. Calatayud, E. Njuguna, S. Mwalusepo, M. Gathara, G. Okuku, A. Kibe, B. Musyoka, D. Williamson, G. Ong'amo, G. Juma, T. Johansson, S. Subramanian, E. Gatebe, B. Le Ru

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In East Africa, lepidopteran stemborers such as Chilo partellus and Busseola fusca are major constraints to production of maize, which is the main staple food crop in the region. Cereals depend on silicon (Si)-based defences to fight off herbivores. Using altitudinal ranges in the East African highlands as ecological surrogates for inferring climate change, it was shown that Si concentrations in soil and maize decreased with altitude. This was attributed, in part, to low temperatures at high altitudes, which negatively affected Si assimilation by maize. Experiments showed that B. fusca was more susceptible to Si than C. partellus. Hence the …

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Gravid Anopheles Gambiae Sensu Stricto Avoid Ovipositing In Bermuda Grass Hay Infusion And It's Volatiles In Two Choice Egg-Count Bioassays, Lynda K. Eneh, Michael N. Okal, Anna Karin Borg-Karlson, Ulrike Fillinger, Jenny M. Lindh May 2016

Gravid Anopheles Gambiae Sensu Stricto Avoid Ovipositing In Bermuda Grass Hay Infusion And It's Volatiles In Two Choice Egg-Count Bioassays, Lynda K. Eneh, Michael N. Okal, Anna Karin Borg-Karlson, Ulrike Fillinger, Jenny M. Lindh

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Background: A number of mosquito species in the Culex and Aedes genera prefer to lay eggs in Bermuda grass (Cynodon dactylon) hay infusions compared to water alone. These mosquitoes are attracted to volatile compounds from the hay infusions making the infusions effective baits in gravid traps used for monitoring vectors of arboviral and filarial pathogens. Since Bermuda grass is abundant and widespread, it is plausible to explore infusions made from it as a potential low cost bait for outdoor monitoring of the elusive malaria vector Anopheles gambiae s.s. Methods: This study investigated preferential egg laying of individual An. gambiae s.s. …

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Influence Of Host-Plant Surface Chemicals On The Oviposition Of The Cereal Stemborer Busseola Fusca, Gerald Juma, Gilles Clément, Peter Ahuya, Ahmed Hassanali, Sylvie Derridj, Cyrile Gaertner, Romain Linard, Bruno Le Ru, Brigitte Frérot, Paul André Calatayud May 2016

Influence Of Host-Plant Surface Chemicals On The Oviposition Of The Cereal Stemborer Busseola Fusca, Gerald Juma, Gilles Clément, Peter Ahuya, Ahmed Hassanali, Sylvie Derridj, Cyrile Gaertner, Romain Linard, Bruno Le Ru, Brigitte Frérot, Paul André Calatayud

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The chemical composition of plant surfaces plays a role in selection of host plants by herbivorous insects. Once the insect reaches the plant, these cues determine host acceptance. Laboratory studies have shown that the stem borer Busseola fusca (Lepidoptera: Noctuidae), an important pest of sorghum and maize in sub-Saharan Africa, is able to differentiate between host and non-host plant species. However, no information is available on the cues used by this insect to seek and accept the host plant. Thus, the role of surface phytochemical stimuli on host selection and oviposition by B. fusca was studied in the laboratory using …

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Uncertainty And Sensitivity Analysis Of A Rift Valley Fever Model, S. A. Pedro, H. E.Z. Tonnang, S. Abelman Apr 2016

Uncertainty And Sensitivity Analysis Of A Rift Valley Fever Model, S. A. Pedro, H. E.Z. Tonnang, S. Abelman

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Rift Valley fever (RVF) is a vector-borne viral disease with pronounced health and economic impacts on domestic animals and humans in much of sub-Saharan Africa. Using techniques of uncertainty and sensitivity analysis (both local derivatives and sampling-based methods) of a mathematical model for RVF transmission in livestock by two population of mosquitoes (Aedes and Culex). We systematically investigate the relative importance of each model parameter for both disease epidemic and endemic activities. The relationship between vertical transmission and basic reproduction number reveals that during epidemic activities vertical transmission accelerates the course of the outbreak as it increases the size of …

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