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International Centre of Insect Physiology and Ecology

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Articles 391 - 420 of 429

Full-Text Articles in Agricultural Science

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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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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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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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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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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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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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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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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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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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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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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Reproductive Performance And Population Dynamics Of Cowpea Aphid (Homoptera: Aphididae) On Leaf Extracts Of Resistant And Susceptible Cowpeas, I. Billy Annan, Ward M. Tingey, George A. Schaefers, Kailash N. Saxena Jan 1996

Reproductive Performance And Population Dynamics Of Cowpea Aphid (Homoptera: Aphididae) On Leaf Extracts Of Resistant And Susceptible Cowpeas, I. Billy Annan, Ward M. Tingey, George A. Schaefers, Kailash N. Saxena

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Membrane feeding studies were conducted to determine the effects of raw juices and chemical extracts of leaves of aphid-resistant (ICV-12) and aphid- susceptible (ICV-1) cultivars of cowpea [Vigna unguiculata L. (Walp.)], on the survival, growth, and reproduction of cowpea aphid Aphis craccivora Koch. Life table and demographic statistics of the cohort population and subsequent generations were estimated. Compared to ICV-1, the leaf juices and chemical extracts of ICV-12 exhibited significant (P ≤ 0.05) adverse effects on aphid survival, growth, and reproduction. Raw leaf juice and ethyl acetate extract of ICV-12 in both water and sucrose significantly (P ≤ 0.05) limited …

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Suitability Of Graminaceous Weed Species As Host Plants For Rice Leaffolders, Cnaphalocrocis Medinalis And Marasmia Patnalis, Z. R. Khan, M. L.P. Abenes, N. J. Fernandez Jan 1996

Suitability Of Graminaceous Weed Species As Host Plants For Rice Leaffolders, Cnaphalocrocis Medinalis And Marasmia Patnalis, Z. R. Khan, M. L.P. Abenes, N. J. Fernandez

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The suitability of 12 graminaceous weeds of ricefields as host plants for two rice leaffolders, Cnaphalocrocis medinalis (Guenée) and Marasmia patnalis Bradley (Lepidoptera: Pyralidae) was compared to a susceptible (IR36) and a moderately resistant (TKM6) rice variety in laboratory and greenhouse tests. Although rice was the most preferred host of the two leaffolder species, their responses to the test weeds varied significantly. Cnaphalocrocis medinalis responded better to most of the test weeds than did M. patnalis, suggesting a wider host range for C. medinalis. Third instar larval orientation and settling, and food consumption and assimilation of C. medinalis on Leersia …

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1,8-Cineole: An Attractant For The Banana Weevil, Cosmopolites Sordidus, Isaiah O. Ndiege, Willam J. Budenberg, Dalmas O. Otieno, Ahmed Hassanali Jan 1996

1,8-Cineole: An Attractant For The Banana Weevil, Cosmopolites Sordidus, Isaiah O. Ndiege, Willam J. Budenberg, Dalmas O. Otieno, Ahmed Hassanali

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1,8-Cineole was identified as one of the electrophysiologically active components of the volatiles from banana cultivars susceptible to the banana weevil. It was also shown to be an attractant for the banana weevil Comopolites sordidus in laboratory behavioural bioassays. The resistant cultivar did not contain 1,8-cineole. β-Phellandrene, which exhibited electrophysiological activity, but did not show any attraction to the banana weevil, was found only in the resistant banana cultivar.

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Linkage Relationships Among Loci Controlling Morphological Traits In Cowpea (Vigna Unguiculata (L.) Walp.), S. M. Githiri, P. M. Kimani, R. S. Pathak Jan 1995

Linkage Relationships Among Loci Controlling Morphological Traits In Cowpea (Vigna Unguiculata (L.) Walp.), S. M. Githiri, P. M. Kimani, R. S. Pathak

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Linkage among loci controlling various morphological traits in cowpea were determined using F2 progenies. Data were collected on individual plants of four crosses segregating for several loci. Recombination estimates between the following pairs of loci were as follows: Sw (swollen vs normal stem base)-Fbc (cream vs green flower buds) (41±4.8%), Pus(purple vs green stems)-Cbr (cocoa-brown vs straw-yellow dry pods) (31±5.7%), Pup(purple vs green immature pods)-Cbr (30±5.7%), Pus-Pup (4±1.5%), Ndt (non-determinate vs determinate)-Pd (peduncle colour) (26±2.8%), Ndt-Hg (semi-erect vs erect plant type) (26±2.8%), Pt(purple vs green pod tips)-Bk (greyish-black vs straw-yellow dry pods) (19±2.4%) and Hg-Bpd (normal vs branching peduncle (24±9.5%). …

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Limonoids From Turraea Floribunda, Baldwyn Torto, Michael D. Bentley, Barbara J.W. Cole, Ahmed Hassanali, Fu Yung Huang, Leslie Gelbaum, Donald G. Vanderveer Jan 1995

Limonoids From Turraea Floribunda, Baldwyn Torto, Michael D. Bentley, Barbara J.W. Cole, Ahmed Hassanali, Fu Yung Huang, Leslie Gelbaum, Donald G. Vanderveer

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Extracts of the root bark of Turraea floribunda have yielded four new limonoids of the havanensin class: 28-nor-4α-carbomethoxy-11β-acetoxy-12α-(2-methylbutanoyloxy)-14,15-deoxyhavanensin-1,7-diacetate; 28-nor-4α-carbomethoxy-11β-hydroxy-12α-(2-methylbutanoyloxy)-14,15-deoxyhavanensin-1,7-diacetate; 18-nor-4α-carbomethoxy-11β-acetoxy-12α-(2-methylbutanoyloxy)-14,15-deoxyhavanensin-1-acetate; and 28-nor-4α-carbomethoxy-7-deoxy-7-oxo-11β-acetoxy-12α-(2-methylbutanoyloxy)-14,15-deoxyhavanensin-1-acetate. The structures were determined by spectroscopic methods. The structure for the first of these compounds was also confirmed by X-ray diffraction methods. © 1995.

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Effect Of Pubescence In Cowpea Resistance To The Legume Pod Borer Maruca Testulalis (Lepidoptera: Pyralidae), S. Oghiakhe Jan 1995

Effect Of Pubescence In Cowpea Resistance To The Legume Pod Borer Maruca Testulalis (Lepidoptera: Pyralidae), S. Oghiakhe

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Pubescence (trichomes) in wild and cultivated cowpeas, Vigna vexillata and V. unguiculata, adversely affected oviposition, mobility, and food consumption and utilisation by the legume pod borer, Maruca testulalis (Geyer), in tests conducted with TVnu 72 (wild, highly resistant and highly pubescent), TVu 946 (semi-wild, moderately resistant and pubescent) and IT82D-716 (cultivated, highly susceptible and pubescent). In free-choice and no-choice tests, significantly (P < 0.05) fewer eggs were laid on 3-week-old potted plants of TVnu 72, the highly pubescent and wild species; this species also received fewer eggs on abaxial and adaxial leaf surfaces. Ovipositional activity on stipules, stem, branches, terminal shoots, adaxial and abaxial leaf surfaces of the susceptible cultivar, IT82D-716 was higher (P < 0.05) than on TVu 946 and TVnu 72. More eggs were laid on the abaxial surfaces than on the adaxial surfaces of leaves for all tests conducted, except for the TVnu 72 no-choice test. Significant negative correlations (r = -0.99** and r = -0.99**) were found between mean number of eggs laid and length and density of non-glandular trichomes. There was a significant negative correlation (r = -0.99**) between larval velocity and length of non-glandular trichomes on pod surface. Similarly, significant negative correlations (r = -0.85* and -0.89*) were found between larval velocity and density and length of non-glandular trichomes on leaf surface. Pods of IT82D-716 and TVnu 72 were the most - and least - preferred for settling by larvae of M. testulalis, respectively. There was a significant positive correlation (r = 0.99**) between larval penetration time on pods and length of non-glandular trichomes. Weight loss, number of feeding punctures and number of larvae on whole pods of TVnu 72 were lower and significantly different (P < 0.05) from IT82D-716 and TVu 946. This study showed that it would be advantageous to use TVnu 72 in a breeding programme to incorporate pubescence into high-yielding commercial cultivars for resistance against M. testulalis and possibly other major pests. © 1995.

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Interrelationship Among Chilo Partellus (Swinhoe) Damage Parameters And Their Contribution To Grain Yield Reduction In Maize (Zea Mays L.), S. O. Ajala, K. N. Saxena Jan 1994

Interrelationship Among Chilo Partellus (Swinhoe) Damage Parameters And Their Contribution To Grain Yield Reduction In Maize (Zea Mays L.), S. O. Ajala, K. N. Saxena

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Understanding the relationship among the spotted stem borer (Chilo partellus) damage parameters and grain yield reduction on maize (Zea mays L.) will aid in elucidation of the most important damage parameters that reduce yield, and may consequently lead to development of functional criteria to quantify tolerance and resistance. Correlations, stepwise multiple regressions and path coefficient analyses were used to study the interrelationship among the three damage parameters (foliar lesions, dead heart and stem tunnelling) and their contribution to grain yield reduction using three separate groups of genotypes in trials conducted between 1990 and 1991. Foliar lesions and stem tunnelling were …

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Effects Of Neem Seed Derivatives On Brown Planthopper Symbiotes, S. Raguraman, R. C. Saxena Jan 1994

Effects Of Neem Seed Derivatives On Brown Planthopper Symbiotes, S. Raguraman, R. C. Saxena

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Populations of intracellular symbiotes declined significantly in brachypterous females of the brown planthopper, Nilaparvata lugens (Stål), which were stressed during nymphal development by caging them on IR20 rice plants treated with 3% neem oil, 5% neem seed kernel aqueous extract, or 10% neem cake aqueous extract. In addition, nymphs grew poorly and symbiote populations in prospective females declined, when reared on rice plants grown in soil treated with neem cake; this indicates systemic action of bioac-tive neem constituents. Addition of custard-apple oil to neem oil did not enhance the inhibitory effects. The effects of neem derivatives on the symbiotes may …

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Distribution And Sampling Of Chilo Partellus (Lepidoptera: Pyralidae) In Maize And Sorghum On The Kenya Coast, W. A. Overholt, K. Ogedah, P. M. Lammers Jan 1994

Distribution And Sampling Of Chilo Partellus (Lepidoptera: Pyralidae) In Maize And Sorghum On The Kenya Coast, W. A. Overholt, K. Ogedah, P. M. Lammers

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The seasonal occurrence and spatial distribution of the crambine stem borer, Chilo partellus (Swinhoe) were investigated in maize, Zea mays, and sorghum, Sorghum bicolor, fields at the Kenya coast. During the vegetative growth stage, small-sized larvae were typically found behind leaf sheaths and in whorls in maize and sorghum. In reproductive and senescent maize, small-sized larvae were also found feeding in ears. Later immature life stages were located predominantly in stems in sorghum, and in the stems and ears in maize. Density and variance estimates of small, medium-, and large-sized larvae and pupae in maize and sorghum were fitted to …

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Grain Yield Losses In Maize (Zea Mays L.) Genotypes In Relation To Their Resistance Against Chilo Partellus (Swinhoe) Infestation At Anthesis, Harish Kumar, Gershon O. Asino Jan 1994

Grain Yield Losses In Maize (Zea Mays L.) Genotypes In Relation To Their Resistance Against Chilo Partellus (Swinhoe) Infestation At Anthesis, Harish Kumar, Gershon O. Asino

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Resistance/susceptibility of 12 maize genotypes to stem borer Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) was measured under artificial infestation at the time of anthesis during the short rainy seasons of 1989/90 and 1990/91. The maize genotypes tested were Inbred A (Kenya), Pwani hybrid (Kenya), Hybrid 511 (Kenya), ICZ2-CM (CIMMYT), MBR-8637 (CIMMYT), MBR-8650 (CIMMYT), MBR-8668 (CIMMYT), Poza Rica 7832 (CIMMYT), Mp704 (USDA), Katumani Composite B (Kenya), Bulk CG 4141 (Zambia), and MMV 400 (Zambia). Under low infestation (50-60 eggs per plant), the differences between susceptible and resistant genotypes in terms of stalk damage or grain damage were not apparent, whereas under high …

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Evidence For Volatile Male-Produced Pheromone In Banana Weevil Cosmopolites Sordidus, William J. Budenberg, Isaiah O. Ndiege, Florence W. Karago Sep 1993

Evidence For Volatile Male-Produced Pheromone In Banana Weevil Cosmopolites Sordidus, William J. Budenberg, Isaiah O. Ndiege, Florence W. Karago

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Females of the banana weevil, Cosmopolites sordidus, were attracted to and made longer visits to live conspecific males, trapped volatiles from males, and dissected male hindguts in a still-air olfactometer. Male weevils were attracted to volatiles trapped from males and made longer visits to live males and volatiles from males. Live females, collected volatiles from females and female hindguts, elicited small or no behavioral responses from either sex. Electroantennogram (EAG) responses from both male and female antennae were elicited by collected volatiles from males and by dichloromethane extracts of male hindguts and bodies but not by surface washes of males. …

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Effectiveness Of The Entomopathogenic Fungus Beauveria Bassiana (Bals.) Vuill. For Control Of The Stem Borer Chilo Partellus (Swinhoe) In Maize In Kenya, Nguya K. Maniania Jan 1993

Effectiveness Of The Entomopathogenic Fungus Beauveria Bassiana (Bals.) Vuill. For Control Of The Stem Borer Chilo Partellus (Swinhoe) In Maize In Kenya, Nguya K. Maniania

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The fungus Beauveria bassiana (Bals.) Vuill. and insecticide trichlorfon were compared for the control of stem borer, Chilo partellus (Swinhoe) in field experiments at different times of infestation. Egg masses of C. partellus at the blackhead stage were pinned to the undersurface of the maize leaves. Two fungal formulations, conidial aqueous suspensions and a granular formulation, were applied. Compared with the untreated checks, the numbers of surviving C. partellus larvae were significantly reduced in treatments where B. bassiana was applied at a concentration of 1013 conidia ha-1 as granules and as two aqueous spray formulations. No significant difference in numbers …

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Striga Hermonthica Resistance In Upland Rice, Z. Harahap, K. Ampong-Nyarko, J. C. Olela Jan 1993

Striga Hermonthica Resistance In Upland Rice, Z. Harahap, K. Ampong-Nyarko, J. C. Olela

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Upland rice breeding lines were evaluated in field trials for resistance to the obligate hemi-root parasite Striga hermonthica at two sites in Kenya in 1990 and 1991. The lines differed in their reaction to S. hermonthica ranging from highly resistant to extremely susceptible. IR 49255-B-B-5-2, IR 38547-B-B-B-7-2-2, IR 47255-B-B-5-4 and Ble Chai were confirmed resistant to S. hermonthica. The indication is that the gene for resistance to S. hermonthica is widespread in rice. © 1993.

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Influence Of Maize Row Spacing On Infestation And Damage Of Intercropped Beans By The Bean Aphid (Aphis Fabae Scop.). I. Incidence Of Aphids, M. W. Ogenga-Latigo, J. K.O. Ampofo, C. W. Baliddawa Jan 1992

Influence Of Maize Row Spacing On Infestation And Damage Of Intercropped Beans By The Bean Aphid (Aphis Fabae Scop.). I. Incidence Of Aphids, M. W. Ogenga-Latigo, J. K.O. Ampofo, C. W. Baliddawa

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Investigations were carried out in the field and in the glasshouse to asses the influence of row spacing of intercrop maize on the incidence of the bean aphid, Aphis fabae Scop. (Homoptera: Aphididae), on common beans, Phaseolus vulgaris L., and on aphid dispersal within the intercrops. Maize was planted in the field twice at a 3-week interval, at row spacings of 0.5, 1.0, 1.5 and 2.0 m, while sole and intercropped beans were planted simultaneously with the second maize, at a row spacing of 0.5 m. Aphis fabae incidence was lower on beans intercropped with densely planted maize, with strong …

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