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Articles 391 - 420 of 443

Full-Text Articles in Agricultural Science

Comparative Life Table Statistics Of Exochomus Flaviventris Reared On The Cassava Mealybug, Phenacoccus Manihoti, Fed On Four Host Plants, B. P. Le Rü, A. Mitsipa Jan 2002

Comparative Life Table Statistics Of Exochomus Flaviventris Reared On The Cassava Mealybug, Phenacoccus Manihoti, Fed On Four Host Plants, B. P. Le Rü, A. Mitsipa

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The demographic statistics of the ladybird Exochomus flaviventris Mader (Coleoptera: Coccinellidae) were investigated under laboratory conditions on the cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Homoptera: Pseudococcidae), reared on four host plants with different levels of antibiotic resistance to the mealybug: two cassava (Manihot esculenta Crantz, Euphorbiaceae) varieties, Incoza and Zanaga, Faux-Caoutchouc (FC) (hybrid of M. esculenta x M. glaziovii Muel. Arg.) and water weed (Talinum triangulare Jack, Portulacacae). Preimaginal mortality, mean oviposition time and total fecundity of female ladybirds were strongly affected by the host plant even though there was no linkage with antibiotic resistance. The net reproduction rates R o …

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Density Effects Of The Banana Weevil, Cosmopolites Sordidus (Germar), On Its Oviposition Performance And Egg And Larval Survivorship, Clifford S. Gold, Godfrey H. Kagezi, Pontiano Nemeye, Philip E. Ragama Jan 2002

Density Effects Of The Banana Weevil, Cosmopolites Sordidus (Germar), On Its Oviposition Performance And Egg And Larval Survivorship, Clifford S. Gold, Godfrey H. Kagezi, Pontiano Nemeye, Philip E. Ragama

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The influence of banana weevil, Cosmopolites sordidus (Germar)(Coleoptera: Curculionidae), population density on oviposition rates and larval survivorship was studied in the laboratory at the Kawanda Agricultural Research Institute in Uganda. This study was undertaken to elucidate the relationship between density-dependent factors and rates of banana weevil increase in the field. Oviposition substrates (corm pieces) were offered to a range of densities of weevils maintained in buckets. Mean oviposition rates per female at densities of 10, 20 and 40 females per bucket were 29, 37 and 53%, respectively, lower than that at a density of 5 females. Nevertheless, total oviposition for …

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Predators Of Mesoplatys Ochroptera In Sesbania Planted-Fallows In Eastern Zambia, G. Sileshi, M. Kenis, C. K.P.O. Ogol, S. Sithanantham Aug 2001

Predators Of Mesoplatys Ochroptera In Sesbania Planted-Fallows In Eastern Zambia, G. Sileshi, M. Kenis, C. K.P.O. Ogol, S. Sithanantham

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Mesoplatys ochroptera Stål (Coleoptera: Chrysomelidae) is a serious pest of the tropical legume sesbania (Sesbania sesban (L.) Merrill) widely used for soil fertility improvement in southern Africa. Surveys were conducted between October 1997 and June 1999 in order to identify the predators of M. ochroptera in sesbania fallows in eastern Zambia. The Heteroptera Afrius yolofa (Guérin-Méneville), Glypsus conspicuus (Westwood), Macrorhaphis acuta Dallas, Mecosoma mensor (Germar), Rhinocoris segmentarius (Germar), and Deraeocoris ostentans (Stål), the carabid beetle Cyaneodinodes fasciger (Chaudoir), the ants Tetramorium sericeiventre Emery and Pheidole sp., and the lacewing Mallada sp. were recorded as predators of M. ochroptera for the …

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Impact Of Solar Radiation Rainfall And Cannibalism On Disappearance Of Maize Stemborers In Kenya, M. J. Bonhof, W. A. Overholt Jan 2001

Impact Of Solar Radiation Rainfall And Cannibalism On Disappearance Of Maize Stemborers In Kenya, M. J. Bonhof, W. A. Overholt

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The effect of solar radiation, rainfall and cannibalism on the disappearance of eggs and larvae of the cereal stemborer Chilo partellus (Swinhoe) were studied. Disappearance and nonviability of egg batches was higher on plants exposed to solar radiation than on shaded plants. Significantly fewer small larvae were recovered from plants exposed to rainfall than from shielded plants. Cannibalism among larvae of the same size was not common except at high larval densities. Contrary to the common belief that disappearance is the result of prédation, these studies show that solar radiation and rainfall might also play an important role in the …

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Greenhouse Trials Of New Bacillus Thuringiensis Isolates For Control Of Chilo Partellus Larvae In Sorghum, Michael Brownbridge Jan 2001

Greenhouse Trials Of New Bacillus Thuringiensis Isolates For Control Of Chilo Partellus Larvae In Sorghum, Michael Brownbridge

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Eight new Bacillus thuringiensis Berliner (Bt) isolates originally recovered from different source materials and geographic locations in Kenya were tested against Chilo partellus (Swinhoe) on sorghum grown in a greenhouse. All isolates had been demonstrated previously to be toxic to this pest. Bt strains were cultured in a liquid growth medium and preserved as powders for experimental application. Three-week-old sorghum plants (4-6 leaves) were artificially infested with 20 neonate C. partellus and sprayed 24 h later with Bt suspensions. Non-infested sorghum and infested non-treated sorghum served as the comparative checks within each experimental trial. Plant development and dead-heart formation were …

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Distribution And Species Composition Of Stemborers And Their Natural Enemies In Maize And Sorghum In Ethiopia, Emana Getu, W. A. Overholt, E. Kairu Jan 2001

Distribution And Species Composition Of Stemborers And Their Natural Enemies In Maize And Sorghum In Ethiopia, Emana Getu, W. A. Overholt, E. Kairu

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Surveys were conducted to determine the species composition of stemborers and their natural enemies in maize and sorghum in 1999 and 2000 in eastern, northern, southern and western Ethiopia. The six species of stemborers found attacking maize and sorghum were Cltilp partellus (Swinhoe) (Lepidoptera: Crambidae), Busseolafiisca Fuller, Sesamia calamistis Hampson (Lepidoptera: Noctuidae), S. nonagrioides botanephaga Tarns and Bowden (Lepidoptera: Noctuidae), Rhynchaenus niger (Horn) (Coleoptera: Rhynchophoridae) and Pissodes dubious (Stroöm) (Coleoptera: Rhynchophoridae). Twenty species of primary parasitoids of eggs, larvae and pupae of Ch. partellus, B. fusca and S. calamistis were recorded. Other natural enemies, including predators, fungi and nematodes, were …

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Relationships Of Stemborer Damage And Plant Physical Conditions To Maize Yield In A Semi-Arid Zone Of Eastern Kenya, Josephine Moraa Songa, Zhou Guofa, William Allan Overholt Jan 2001

Relationships Of Stemborer Damage And Plant Physical Conditions To Maize Yield In A Semi-Arid Zone Of Eastern Kenya, Josephine Moraa Songa, Zhou Guofa, William Allan Overholt

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A field survey on maize stemborers, stemborer damage, maize plant physical conditions, and maize yield was conducted in eastern Kenya under natural conditions. Chilo partellus was the dominant stemborer accounting for 89.5 % of all borers. Stemborer damage greatly reduced maize yield, with tunnel lengths greater than 20 cm causing a 40 % reduction of potential yield. A 33 % yield loss was found in plants with more than one stemborer exit hole. Each stemborer (at harvest time) was correlated with a 8-10 % yield loss. Good plant physical characteristics significantly increased grain yield. Principle component analysis showed that stemborer …

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Habitat Management Strategies For The Control Of Cereal Stemborers And Striga In Maize In Kenya, Z. R. Khan, J. A. Pickett, L. Wadhams, F. Muyekho Jan 2001

Habitat Management Strategies For The Control Of Cereal Stemborers And Striga In Maize In Kenya, Z. R. Khan, J. A. Pickett, L. Wadhams, F. Muyekho

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Maize is the principal food and cash crop for millions of people in the predominantly mixed crop-livestock farming systems in Kenya. Stemborers and striga (Striga hermonthica) are major constraints to increased maize production in eastern Africa. An intercropping and trap crop system has been developed, using a ‘push-pull’ strategy, for the control of stemborers in small scale maize farming systems. The ‘push-pull’ strategy involves trapping stemborers on highly susceptible trap plants (pull) and driving them away from the crop using repellent intercrops (push). Napier grass (Pennisetum piirpiirenm Schumach) and Sudan grass (Sorghum vulgare sudanense Stapf J are used as trap …

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Distribution And Abundance, In Maize And Sorghum, Of Lepidopteran Stemborers And Associated Indigenous Parasitoids In Zanzibar, E. I. Nlyibigira, Z. S. Abdallah, W. A. Overholt Jan 2001

Distribution And Abundance, In Maize And Sorghum, Of Lepidopteran Stemborers And Associated Indigenous Parasitoids In Zanzibar, E. I. Nlyibigira, Z. S. Abdallah, W. A. Overholt

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Studies to determine the relative abundance and distribution of stemborer species and their associated parasitoids in maize and sorghum were carried out during the 1995-1996 and 19992000 cropping seasons on Unguja and Pemba, the two main islands of Zanzibar. Three stemborer species were found on both islands in maize and sorghum, with the exotic species Chilo partellns (Swinhoe) (Crambidae) being the most abundant and widely distributed species, accounting for 75.3 % of stemborer attack. It was followed by Sesamia calamistis Hampson (Noctuidae) and C/i. oriclialcociliellus Strand (Crambidae). Stemborer abundance was significantly higher in Pemba (1.47 ± 0.20) than Unguja (0.85 …

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Changes In The Distribution Of Lepidopteran Maize Stemborers In Kenya From The 1950s To 1990s, Zhou Guofa, William A. Overholt, Moses B. Mochiah Jan 2001

Changes In The Distribution Of Lepidopteran Maize Stemborers In Kenya From The 1950s To 1990s, Zhou Guofa, William A. Overholt, Moses B. Mochiah

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Three hundred and ninety-two maize fields in the southern arable zone of Kenya were sampled for lepidopteran cereal stemborers from 1996-2000. Chilo partelhis (Swinhoe) was the most abundant stemborer, and was found at all locations with elevations below 1500 m, and at some locations between 1500 and 2300 m. The highest density of C. partelhis was in the semi-arid ecological zone of eastern Kenya. Chilo orichalcociliellus (Strand) was found in the lowland southern coastal area, and a few inland sites on the border of Tanzania in southeastern Kenya. Busseola fusca Fuller was dominant in highland areas. In the Lake Victoria …

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Farmers’ Perceptions Of Importance, Control Methods And Natural Enemies Of Maize Stemborers At The Kenya Coast, M. J. Bonhof, A. Van Huis, F. G. Kiros, N. Dlbogo Jan 2001

Farmers’ Perceptions Of Importance, Control Methods And Natural Enemies Of Maize Stemborers At The Kenya Coast, M. J. Bonhof, A. Van Huis, F. G. Kiros, N. Dlbogo

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A survey among 240 resource-poor farmers at the Kenya coast indicated that insect pests were considered to be the main production constraint. Over 70% of respondents mentioned stemborers to be the most important insect pest. Unlike the eggs and adults, stemborer larvae and pupae were frequently seen by farmers. Alternative gramineous host plants for pests were common near maize fields and were often not destroyed until after the first rains. Nearly all farmers left dry stems and stubble in the field after harvest. Farmers knew of many methods for controlling stemborers, but only 32 and 56% of farmers in Kilifi …

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Pathogenicity And Antifeedant Activity Of Entomopathogenic Hyphomycetes To The Cowpea Leaf Beetle, Ootheca Mutabilis Shalberg, S. Ekesi Jan 2001

Pathogenicity And Antifeedant Activity Of Entomopathogenic Hyphomycetes To The Cowpea Leaf Beetle, Ootheca Mutabilis Shalberg, S. Ekesi

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Conidial suspensions of four isolates each of Bcauvcria bassiana and Melnrhizhtm anisopliae were evaluated in the laboratory for their virulence to adult Ootlicca mntabilis. All the isolates tested were pathogenic to the beetle, but to varying degrees. Three of them, B. bassiana CPD 3 and CPD10 and M. anisopliae CPD 6 were superior to all other isolates in terms of mortality induced on adult beetle, LT50 and LC50, with B. bnssiana CPD 3 having the lowest LC50 value. In feeding assayi consumption by beetles treated with B. bnssiana CPD 3 was significantly reduced within 2 days treatment (DAT) and the …

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Susceptibility Of The Legume Flower Thrips To Metarhizium Anisopliae On Different Varieties Of Cowpea, S. Ekesi, N. K. Maniania, W. Lwande Jan 2000

Susceptibility Of The Legume Flower Thrips To Metarhizium Anisopliae On Different Varieties Of Cowpea, S. Ekesi, N. K. Maniania, W. Lwande

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The susceptibility of Megalurothrips sjostedti to Metarhizium anisopliae when reared on susceptible, tolerant, and moderately resistant varieties of cowpea at different constant temperatures was evaluated in the laboratory. Insects were exposed either to direct spray of the conidia or to fungus-treated floral tissues. Mortality was significantly higher on the moderately resistant variety at all temperatures compared to the susceptible and tolerant varieties. Correspondingly, lethal time and lethal concentration values were significantly shorter and lower, respectively, on the moderately resistant variety compared to the other varieties, thus indicating that the two control methods are compatible as part of an integrated pest …

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Evaluation Of Banana Cultivars For Resistance To The Banana Weevil Cosmopolites Sordidus And Nematode Complex In Western Kenya, T. Musabyimana, K. V. Seshu Reddy, L. Ngode, J. S. Prasad Jan 2000

Evaluation Of Banana Cultivars For Resistance To The Banana Weevil Cosmopolites Sordidus And Nematode Complex In Western Kenya, T. Musabyimana, K. V. Seshu Reddy, L. Ngode, J. S. Prasad

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Banana weevil Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae) and parasitic nematodes are often together on the same banana mat. Both pests have been recognized as major constraints to banana production. They may cause up to 85% yield loss in banana. Hence, both pests should be investigated together to define a control strategy for this complex constraint. With this view, our investigation was carried out in a naturally nematode-weevil infested farmer's field to search for host plant resistance to both pests. Pratylenchus goodeyi, Helicotylenchus multicinctus and Meloidogyne spp. were the most commonly occurring nematodes in the experiment and were often in mixed …

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Powdered Neem Seed And Cake For Management Of The Banana Weevil, Cosmopolites Sordidus, And Parasitic Nematodes, T. Musabyimana, R. C. Saxena, E. W. Kairu, C. K.P.O. Ogol, Z. R. Khan Jan 2000

Powdered Neem Seed And Cake For Management Of The Banana Weevil, Cosmopolites Sordidus, And Parasitic Nematodes, T. Musabyimana, R. C. Saxena, E. W. Kairu, C. K.P.O. Ogol, Z. R. Khan

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Field trials were conducted in Kenya with 'Nakyetengu', an East African highland banana cultivar (AAA-EA), highly susceptible to banana pests. Regardless of soil fertility levels, incorporation around the plant base of powdered neem (Azadirachta indica A. Juss.) seed or cake at 60-100 g/mat at 4-month intervals, gave better control of the banana weevil, Cosmopolites sordidus (Germar), and of parasitic nematodes, than that achieved with soil application of Furadan 5G (carbofuran) at 60 g/mat at 6-month intervals. Compared with untreated control, fruit yield in most of the neem treatments was significantly higher, particularly during the second cycle of crop production. Neem …

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Effect Of Volatiles And Crude Extracts Of Different Plant Materials On Egg Viability Of Maruca Vitrata And Clavigralla Tomentosicollis, S. Ekesi Jan 2000

Effect Of Volatiles And Crude Extracts Of Different Plant Materials On Egg Viability Of Maruca Vitrata And Clavigralla Tomentosicollis, S. Ekesi

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The effect of volatiles and aqueous extracts of black pepper, Piper guineense; neem seed, Azadirachta indica; garlic bulb, Allium sativum; and onion bulb, Allium cepa on egg viability of Maruca vitrata Fab. (Lepidoptera: Pyralidae) and Clavigralla tomentosicollis Stal (Heteroptera: Coreidae) was evaluated in laboratory experiments. Compared with the other treatments, volatiles of black pepper and garlic bulb were superior in reducing hatch of freshly laid (12-h-old) eggs of both species of insects. Volatiles of onion bulb and neem seed had no effect on egg hatch. When aqueous extracts of the various plant materials were tested at 5%, 10% and 15%, …

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Selection Of Virulent Isolates Of Entomopathogenic Hyphomycetes Against Clavigralla Tomentosicollis Stål. And Evaluation In Cage Experiment Using Three Cowpea Varieties, S. Ekesi Dec 1999

Selection Of Virulent Isolates Of Entomopathogenic Hyphomycetes Against Clavigralla Tomentosicollis Stål. And Evaluation In Cage Experiment Using Three Cowpea Varieties, S. Ekesi

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The virulence of 8 isolates of entomopathogenic hyphomycetes against adult and 5th instar nymph of Clavigralla tomentosicollis was evaluated in the laboratory at 4 different concentrations of inoculum. At all concentrations, Beauveria bassiana CPD 9 and Metarhizium anisopliae CPD 5 caused the highest mortality in adult bug ranging from 58 to 97% and 53 to 100%, respectively at 7 days post inoculation. The same isolates had the shortest LT50 (3.5 and 4.1 days, respectively) and the lowest LC50 (1.8 × 105 and 9.8 × 104 conidia ml-1) values in adult insects. In nymphs, M. anisopliae CPD 5 was the most …

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Simulation Model For Maize Crop Growth Based On Acquisition And Allocation Processes For Carbohydrate And Nitrogen, O. Bonato, F. Schulthess, J. Baumgärtner Dec 1999

Simulation Model For Maize Crop Growth Based On Acquisition And Allocation Processes For Carbohydrate And Nitrogen, O. Bonato, F. Schulthess, J. Baumgärtner

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A population model for maize growth and development driven by temperature, solar radiation, soil water and soil nitrogen is presented. A time-varying distributed delay model is used to describe the dynamics of the attributes number, biomass and nitrogen belonging to leaf, root, stem, grain, rachys and husk populations. Photosynthate production as well as water and nitrogen acquisition was simulated with a demand-driven ratio-dependent functional response model. Carbohydrate, water and nitrogen supply-demand ratios were calculated to control the growth of different populations of plant. The metabolic pool model was used to allocate carbohydrates to plant subunits. The model was validated with …

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Cleome Hirta Essential Oil As Livestock Tick (Rhipicephalus Appendiculatus) And Maize Weevil (Sitophilus Zeamais) Repellent, M. W. Ndungu, S. C. Chhabra, W. Lwande Oct 1999

Cleome Hirta Essential Oil As Livestock Tick (Rhipicephalus Appendiculatus) And Maize Weevil (Sitophilus Zeamais) Repellent, M. W. Ndungu, S. C. Chhabra, W. Lwande

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The repellency of the essential oil of the shrub Cleome hirta and of three identified constituents (phytol, (+)-cedrol, n-octacosane) was evaluated against the livestock tick, Rhipicephalus appendiculatus and the maize weevil, Sitophillus zeamais. In a tick climbing repellency bioassay, the oil exhibited repellency which, at the highest dose, was comparable to that of the commercial arthropod repellent N,N-diethyltoluamide (DEET). In a Y-tube olfactometer bioassay, the oil showed higher or comparable repellency against S. zeamais relative to DEET at all the doses tested. The potential of C. hirta in livestock tick and maize weevil control is discussed. Copyright (C) 1999 Elsevier …

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Efficacy Of Neem Seed Derivatives Against Nematodes Affecting Banana, T. Musabyimana, R. C. Saxena Jan 1999

Efficacy Of Neem Seed Derivatives Against Nematodes Affecting Banana, T. Musabyimana, R. C. Saxena

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Soil applications of powdered neem seed or neem cake at 100 g/plant at planting and, subsequently, at 3-month intervals, reduced the populations of Pratylenchus goodeyi Sher and Allen and Meloidogyne spp. on par with Furadan 5G (carbofuran) applied at 40 g/plant at planting and then at 6-month intervals to banana plants grown in 100-l containers with controlled levels of banana nematode infestations. Eight months after planting, banana plants treated with powdered neem cake, seed or kernel or with neem oil had 4 to 95 times fewer parasitic nematodes than the untreated control. However, only neem cake powder or neem seed …

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Genetic Relationships Among Subspecies Of Vigna Unguiculata (L.) Walp. Based On Allozyme Variation, R. S. Pasquet Jan 1999

Genetic Relationships Among Subspecies Of Vigna Unguiculata (L.) Walp. Based On Allozyme Variation, R. S. Pasquet

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The cowpea [Vigna unguiculata (L.) Walp.] is a morphologically and genetically variable species composed of wild perennial, wild annual, and cultivated forms that are mainly used for edible seeds and pods. In this study, genetic variation in 199 germplasm accessions of wild and cultivated cowpea was evaluated using an allozyme analysis. The results from this survey showed that wild cowpea exhibits genetic variation perfectly fitted with the existing morphological classification. The cowpea gene-pool is characterized by its unusually large size. It encompasses taxa (ranked as subspecies) that could be considered as different species considering the high genetic distances observed between …

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Potential Of The Entomopathogenic Fungus, Metarhizium Anisopliae (Metsch.) Sorokin For Control Of The Legume Flower Thrips, Megalurothrips Sjostedti (Trybom) On Cowpea In Kenya, S. Ekesi, N. K. Maniania, K. Ampong-Nyarko, I. Onu Nov 1998

Potential Of The Entomopathogenic Fungus, Metarhizium Anisopliae (Metsch.) Sorokin For Control Of The Legume Flower Thrips, Megalurothrips Sjostedti (Trybom) On Cowpea In Kenya, S. Ekesi, N. K. Maniania, K. Ampong-Nyarko, I. Onu

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Field experiments were conducted at Mbita, western Kenya for two seasons to evaluate the potential of the entomopathogenic fungus, Metarhizium anisopliae (Metsh.) Sorokin, for biological control of the legume flower thrips, Megalurothrips sjostedti (Trybom), on cowpea. An ultra-low-volume (ULV) oil/aqueous formulation and a high-volume (HV) aqueous formulation of conidia were applied three times each at two concentrations of 1 x 1011 and 1 x 1013 conidia ha-1. Compared with the untreated controls, both formulations significantly reduced thrips populations and plant damage in both seasons. Adult insects collected from fungal-treated plots and reared in the laboratory showed a high mortality due …

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Morphological Study Of Cultivated Cowpea Vigna Unguiculata (L.) Walp. Importance Of Ovule Number And Definition Of Cv Gr Melanophthalmus, Rémy Stéphane Pasquet Jan 1998

Morphological Study Of Cultivated Cowpea Vigna Unguiculata (L.) Walp. Importance Of Ovule Number And Definition Of Cv Gr Melanophthalmus, Rémy Stéphane Pasquet

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More than 400 cultivated cowpea accessions were studied using 29 morphophysiological characters. The analysis of data contrasts evolved cultivars and more primitive cultivars (and wild forms) according to seed size on the one hand and early and late flowering (under inductive conditions) on the other hand. The latter character is markedly correlated with ovule number. Photosensitive and early-flowering photoindependent cultivars have 11-17 ovules per pod and late flowering photoindependent cultivars have 16-25 ovules per pod. The analysis leads to assigning the accessions studied to the following different cultigroups: cv gr Unguiculata, cv gr Sesquipedalis, cv gr Biflora and cv gr …

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Evidence Of Antibiosis Resistance To The Spotted Stemborer, Chilo Partellus (Swinhoe) In A Maize (Zea Mays L.) Population, C. J.M. Mutinda, K. N. Saxena, S. O. Ajala, P. O. Aviecho Jan 1998

Evidence Of Antibiosis Resistance To The Spotted Stemborer, Chilo Partellus (Swinhoe) In A Maize (Zea Mays L.) Population, C. J.M. Mutinda, K. N. Saxena, S. O. Ajala, P. O. Aviecho

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S2 line and S2 test-cross recurrent selection procedures were initiated to improve the resistance of a maize (Zen mays L.) population to the spotted stemborer, Chllo partclltis (Swinhoe) (Lepidoptera: Pyralidae). Thirty-five selections developed from the population were evaluated for resistance to the stemborer in western Kenya. Resistance was rated according to leaf feeding (LF), stem tunnelling (ST) and deadheart formation (DH) following artificial infestation with first-instar C. pnrtcUus. Larval establishment and growth were also assessed. The reduction in foliar damage ratings, percentage stem length tunnelled, and percentage of plants showing deadheart after one cycle of recurrent selection were 4.38 %, …

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The Impact Of Ixodiphagus Hookeri, A Tick Parasitoid, On Amblyomma Variegatum (Acari: Ixodidae) In A Field Trial In Kenya, E. N. Mwangi, S. M. Hassan, G. P. Kaaya, S. Essuman Jan 1997

The Impact Of Ixodiphagus Hookeri, A Tick Parasitoid, On Amblyomma Variegatum (Acari: Ixodidae) In A Field Trial In Kenya, E. N. Mwangi, S. M. Hassan, G. P. Kaaya, S. Essuman

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In an experiment to investigate the effect of the tick parasitoid, Ixodiphagus hookeri, on tick numbers on cattle, 150 000 parasitoids were released over a period of 1 year in a field where ten cattle infested with multiple tick species were kept. Amblyomma variegatum was reduced from 44 to two ticks per animal while Rhipicephalus appendiculatus increased over the time of parasitoid release. During the time of release 51% of the nymphs of A. variegatum collected from the animals were parasitized. The recovery of the parasitoids after the releases were stopped was only 9%. The total numbers of A. variegatum …

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Suitability Of West African Gramineous Stemborers For The Development Of Cotesia Species, Y. Hailemichael, F. Schulthess, J. W. Smith, W. A. Overholt Jan 1997

Suitability Of West African Gramineous Stemborers For The Development Of Cotesia Species, Y. Hailemichael, F. Schulthess, J. W. Smith, W. A. Overholt

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The palaeotropical, gregarious, endoparasitic braconids Cotesia sesamiae, Cotesia flavipes and Cotesia chilonis were recently imported into Benin as candidates for biological control of stem and cob borers of maize. Host acceptability and host suitability of six gramineous borers occurring in western Africa, namely the noctuids Sesamia calamistis, Sesamia poephaga, Busseola fusca and the pyralids Contesta ignefiisalis, Eldana saccharina and Mussidia nigrivenella, to these candidate parasitoids was evaluated in order to gain insight into the physiological suitability of the natural and factitious hosts. All hosts were accepted by all Cotesia spp., except M. nigrivenella which was not attacked by Co. chilonis. …

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Neem Seed Extract Spray Applications As Low-Cost Inputs For Management Of The Flower Thrips In The Cowpea Crop, R. C. Saxena, E. L. Kidiavai Jan 1997

Neem Seed Extract Spray Applications As Low-Cost Inputs For Management Of The Flower Thrips In The Cowpea Crop, R. C. Saxena, E. L. Kidiavai

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In field trials conducted at the Experiment Station and in a farmer's field at Mbita near the shores of Lake Victoria, Kenya, applications of 2% or 3% neem seed extract (NSE) @ 200 l/ha with a knapsack sprayer at 38, 47 and 51 days after emergence (DE) of the cowpea crop or 5%, 10% or 20% NSE sprayed @ 10 l/ha with an ultra-low-volume applicator at 31, 39 and 49 DE often significantly reduced the number of larvae of the flower thrips, Megalurothrips sjostedti (Trybom), in cowpea flowers recorded 2 days after each treatment. Also fewer adults occurred in flowers …

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Combining Ability Of Resistance To The Sorghum Shootfly, Atherigona Soccata And Stemborer Chilo Partellus In Grain Sorghum, Sorghum Bicolor, A. A. Elbadawi, A. M. Nour, R. S. Pathak Jan 1997

Combining Ability Of Resistance To The Sorghum Shootfly, Atherigona Soccata And Stemborer Chilo Partellus In Grain Sorghum, Sorghum Bicolor, A. A. Elbadawi, A. M. Nour, R. S. Pathak

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Combining ability of resistance to the sorghum shootfly, Atherigona soccata and spotted stemborer, Chilo partellus in grain sorghum was analysed on a seven-parents diallel in a field trial at the ICIPE Mbita Point Field Station, western Kenya during the 1990 long rainy season. Lines with best performance for each of the four measured resistance parameters were also found to be the best general combiners. Resistance to leaf damage and number of holes/metre were controlled by additive gene effects whereas resistance to deadheart and stem tunnelling were controlled by additive and non-additive gene effects. Parents IS-1044, IS-12308 and IS-2269 with their …

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Synthesis, Analysis, And Field Activity Of Sordidin, A Male-Produced Aggregation Pheromone Of The Banana Weevil, Cosmopolites Sordidus, Seetharaman Jayaraman, Isaiah O. Ndiege, Allan C. Oehlschlager, Lilliana M. Gonzalez, Dennis Alpizar, Mario Falles, William J. Budenberg, Peter Ahuya Jan 1997

Synthesis, Analysis, And Field Activity Of Sordidin, A Male-Produced Aggregation Pheromone Of The Banana Weevil, Cosmopolites Sordidus, Seetharaman Jayaraman, Isaiah O. Ndiege, Allan C. Oehlschlager, Lilliana M. Gonzalez, Dennis Alpizar, Mario Falles, William J. Budenberg, Peter Ahuya

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An efficient synthesis of the diastereoisomers of sordidin (1), a male-produced aggregation pheromone of Cosmopolites sordidus, has been developed from commercially available 4-methylpent-4-en-2-ol (2). Preparation of eχo-β-sordidin (1a) and endo-β-sordidin (1b) is via the anti epoxide, 4d, which is derived via iodocarbonation of 2. The endo-α-sordidin (1c) and eχo-α-sordidin (1d) are prepared from the corresponding syn epoxide, which is available via stereo controlled epoxidation of the triisopropylsilyloxy derivative, 3b. Silyloxy derivatives of the epoxides, 4 efficiently alkylate the anions of N-cyclohexyldiethylketimine (6a) and 3-pentanone N,N-dimethylhydrazone (6b). Acidic work-up of these alkylation reactions promotes cyclization to give 1. Gram quantities of …

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Genetics Of Resistance To Aphis Craccivora In Cowpea, S. M. Githiri, K. Ampong-Nyarko, E. O. Osir, P. M. Kimani Jan 1996

Genetics Of Resistance To Aphis Craccivora In Cowpea, S. M. Githiri, K. Ampong-Nyarko, E. O. Osir, P. M. Kimani

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Inheritance of aphid resistance and allelic relationships among sources of resistance was studied in the parents, F1, F2, F3, and backcross populations of cowpea crosses. Each 4-day old seedling was infested with five fourth-instar aphids. Seedling reaction was recorded 14-16 days after infestation when the susceptible check was killed. The segregation data from eight crosses between resistant and susceptible cowpea cultivars indicated that aphid resistance was inherited as a monogenic dominant trait. Segregation data from crosses among eight resistant cultivars indicated that one or two loci and modifier(s) were involved in the expression of resistance to aphids. It was suggested …

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