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1997

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Articles 91 - 105 of 105

Full-Text Articles in Entomology

Progeny Production And Sex Ratios Of Field Populations Of The Parasitoids Cotesia Flavipes And Cotesia Sesamiae Reared From Gramineous Stemborers In Coastal Kenya, Charles O. Omwega, William A. Overholt Jan 1997

Progeny Production And Sex Ratios Of Field Populations Of The Parasitoids Cotesia Flavipes And Cotesia Sesamiae Reared From Gramineous Stemborers In Coastal Kenya, Charles O. Omwega, William A. Overholt

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Progeny production and sex ratios of the parasitoids Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) and its exotic congener Cotesia flavipes Cameron (Hymenoptera: Braconidae) emerging from three species of field-collected stemborers were compared. There were no significant differences in numbers of progeny of the two parasitoids from the African stemborers, Chilo orichalcociliellus (Strand) (Lepidoptera: Pyralidae) and Sesamia calamistis Hampson (Lepidoptera: Noctuidae). Cotesia flavipes produced more progeny than C. sesamiae on large larvae of its coevolved Asian host, Chilo partellus (Swinhoe). No significant differences in the number of parasitoid progeny were observed for different-sized Ch. orichakocilidltis or S. calamistis larvae. These data suggest …

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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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Haemolymph Pigment Composition As A Chemometric Indicator Of Phase In The Desert Locust, Schistocerca Gregaria, Hassane Mahamat, Ahmed Hassanali, David Munyinyi Jan 1997

Haemolymph Pigment Composition As A Chemometric Indicator Of Phase In The Desert Locust, Schistocerca Gregaria, Hassane Mahamat, Ahmed Hassanali, David Munyinyi

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The blue biliverdin pigment in the haemolymph of Schisfocerca gregria Forskâl(Orthoptera: Acrididae) was shown to be associated with all the stages and ages of the solitary-reared (solitarious) insects, irrespective of their origin or diet. The pigment was absent or present in very small quantities in the crowd-reared (gregarious) insects. The ratio of absorbance at 460 run and 680 run, the former representing the A,max for the carotenoid pigment and the latter for the biliverdin, provides a clearcut index for partitioning the phases. The mean value of the index for the gregarious group fell in the range 3.69 to 4.78. That …

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Natural Enemies Of Cereal Stemborers In East Africa: A Review, M. J. Bonhof, W. A. Overholt, A. Van Huis, A. Polaszek Jan 1997

Natural Enemies Of Cereal Stemborers In East Africa: A Review, M. J. Bonhof, W. A. Overholt, A. Van Huis, A. Polaszek

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The noctuids Busseola fusca and Sesamia calamistis and the pyraloids Chilo partellus, Chilo orichakocilielhis and Eldana saccharina are the most important stemborers of maize in East Africa. A wide range of egg, larval and pupal parasitoids of stemborers have been identified, but information on predators, nematodes and microbial pathogens is less extensive. The most abundant and widespread parasitoids in the East African region are the egg parasitoids Telenomus spp. and Trichogramma spp., the larval parasitoids Cotesia sesamiae and Sturmiopsis parasitica and the pupal parasitoids Pediobiusfiirvus and Dentichasmias busseolae. Predators, such as ants, spiders and earwigs can cause high mortality of …

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Utilisation Of Wild Gramineous Plants For Management Of Cereal Stemborers In Africa, Z. R. Khan, P. Chiliswa, K. Ampong-Nyarko, L. E. Smart, A. Polaszek, J. Wandera, M. A. Mulaa Jan 1997

Utilisation Of Wild Gramineous Plants For Management Of Cereal Stemborers In Africa, Z. R. Khan, P. Chiliswa, K. Ampong-Nyarko, L. E. Smart, A. Polaszek, J. Wandera, M. A. Mulaa

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Field trials in Kenya demonstrated that the forage grass, Sorghum vulgäre sudanense (Sudan grass) attracted greater oviposition by stemborers than cultivated maize, resulting in significant increase in maize yield. On the other hand, the non-host forage plant, Melinis minutiflora (molasses grass), when inter-cropped with maize, repelled gravid stemborer females from ovipositing on maize, resulting in significant reduction in stemborer infestation. Using these trap- and repellent gramineous plants, a novel pest management approach based on a 'push-pull' or stimulo-deterrent diversionary strategy is being developed where stemborers are repelled from the food crop and are simultaneously attracted to a discard or trap …

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Les Inhibiteurs Des Facteurs Humoraux Chez Les Criquets Migrateurs, Schistocerca Gregaria Et Locusta Migratoria: Perspectives D'Utilisation Dans La Lutte Biologique, D. Dakouo, S. Essuman, S. K. Raina, M. Bréhélin, Latifa Drif Jan 1997

Les Inhibiteurs Des Facteurs Humoraux Chez Les Criquets Migrateurs, Schistocerca Gregaria Et Locusta Migratoria: Perspectives D'Utilisation Dans La Lutte Biologique, D. Dakouo, S. Essuman, S. K. Raina, M. Bréhélin, Latifa Drif

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Haemolymph from the locusts Schistocercagregaria and Locustamigratoria contains humoral factors such as lectin and phenoloxidase system. In vitro studies demonstrated that phenoloxidase system can be activated by LPS, laminarin, Malamoeba locustae cysts, trypsin and methanol. Haemolymph showed agglutination activity for mammalian erythrocytes and protozoa (M. locustae, Leishmania major and Trypanosoma brucei). A purified lectin was isolated fromhaemolymphby affinity chromatography. Analysis by SDS-PAGE gave a single band at 80 kD while on native PAGE, it gave a single band at 650 kD. Inhibitors of the two humoral factors were investigated. Lectin activity was inhibited by nitrophenyl a D-galactopyranoside in both cases …

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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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Vitellogenin Titres In Normal And Accelerated Maturation Of Gragarious-Phase Schistocerca Gregaria, Hassane Mahamat, Ahmed Hassanali, Hans Joerg Ferenz Jan 1997

Vitellogenin Titres In Normal And Accelerated Maturation Of Gragarious-Phase Schistocerca Gregaria, Hassane Mahamat, Ahmed Hassanali, Hans Joerg Ferenz

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Isolation of vitellogenin of the Schistocerca gregoria (Forskal) in its gregarious phase was achieved by a combination of gel permeation and anion exchange chromatography. Staining for carbohydrate and lipid moieties showed that the vitellogenin is a glycolipoprotein. The vitellogenin of S. gregaria has a native molecular weight of about 700 kDa. On SDS-PAGE, the protein showed nine apoproteins of about 124, 120, 105, 60, 59, 58, 57, 53 and 34 kD. Determination of the levels of vitellogenin by ELISA in the haemolymph of maturing females showed that those exposed to mature males from 1 to 2 days after ecdysis had …

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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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Host Location And Acceptance By Cotesia Flavipes Cameron And C. Sesamiae (Cameron) (Hymenoptera: Braconidae), Parasitoids Of African Gramineous Stemborers: Role Of Frass And Other Host Cues, Adele J. Ngi-Song, William A. Overholt Jan 1997

Host Location And Acceptance By Cotesia Flavipes Cameron And C. Sesamiae (Cameron) (Hymenoptera: Braconidae), Parasitoids Of African Gramineous Stemborers: Role Of Frass And Other Host Cues, Adele J. Ngi-Song, William A. Overholt

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Naive females of Cotesia flavipes Cameron and Cotesia sesamiae (Cameron) were attracted, in a T-tube olfactometer, to volatile kairomones from frass produced by Chilo partellus (Swinhoe), Chilo orichalcociliellus Strand, Sesamia calamistis Hampson, and Busseola fusca (Fuller) fed on maize (Zea mays L.), sorghum [Sorghum bicolor (L.)], and napier grass (Pen. nisetum purpureum Schumach). In dual-choice tests, C. flavipes and C. sesamiae were generally unable to discriminate between volatiles from frass produced by any of the four different stemborer species fed on maize stalk. When larvae of C. partellus and S. calamistis were washed in distilled water, their acceptance by both …

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Biosystematics Of The Cotesia Flavipes Species Complex (Hymenoptera: Braconidae): Morphometrics Of Selected Allopatric Populations, Susan W. Kimani-Njogu, William A. Overholt, James Woolley, Annette Walker Jan 1997

Biosystematics Of The Cotesia Flavipes Species Complex (Hymenoptera: Braconidae): Morphometrics Of Selected Allopatric Populations, Susan W. Kimani-Njogu, William A. Overholt, James Woolley, Annette Walker

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Morphometric studies of allopatric populations of the Cotesia fiavipes species complex representing three putative species; C. flavipes Cameron, C. sesamiae (Cameron) and C. chilonis (Matsumura), were conducted. Sixteen characters were measured. Principal component analysis separated the complex into three somewhat overlapping groups that corresponded well with previous concepts of the species. Canonical variate analysis separated the complex into three distinct clusters with populations from Africa together, populations from Asia and the Neotropics forming a second cluster, and material from China and Japan forming a third cluster. The Mahalanobis squared distances between the three clusters were nearly equal. Results support recognition …

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Diel Activity Patterns And Host Preferences Of Glossina Fuscipes Fuscipes (Diptera: Glossinidae) Along The Shores Of Lake Victoria, Kenya, M. M. Mohamed-Ahmed, A. Odulaja Jan 1997

Diel Activity Patterns And Host Preferences Of Glossina Fuscipes Fuscipes (Diptera: Glossinidae) Along The Shores Of Lake Victoria, Kenya, M. M. Mohamed-Ahmed, A. Odulaja

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Diurnal activity patterns and host preference of Glossina fuscipes fuscipes Newstead were studied in forest and linear habitats along Lake Victoria shore, Kenya. The objective was to identify the preferred hosts of G. f. fuscipes, the emanations of which may be attractive to this species. Hourly catches of flies in biconical traps were related to changes in the weather and the prevalence of hosts in the vicinity of traps. Flies were mainly active between 0800 and 1600 h, with males peaking around 1100 h and females around 1300 h. Activity of flies correlated directly with light intensity and temperature, but …

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Changes Over Twelve Years In Populations Of Glossina Pallidipes And Glossina Longipennis (Diptera: Glossinidae) Subject To Varying Trapping Pressure At Nguruman, South-West Kenya, R. Brightwell, R. D. Dransfield, P. Stevenson, B. Williams Jan 1997

Changes Over Twelve Years In Populations Of Glossina Pallidipes And Glossina Longipennis (Diptera: Glossinidae) Subject To Varying Trapping Pressure At Nguruman, South-West Kenya, R. Brightwell, R. D. Dransfield, P. Stevenson, B. Williams

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Long term changes in the size of populations of the tsetse Glossina pallidipes Austen and G. longipennis Corti Were monitored over a 12 year period at Nguruman in south-western Kenya. Tsetse populations were subject to droughts of varying intensity and, from 1987, to trapping, initially by a research organization, and later by a community-based development project. Populations were mainly sampled using odour-baited biconical traps, with data from other monitoring traps corrected accordingly. Mark-release-recapture studies were carried out to relate trap catches to absolute population size, and to quantify movement between subpopulations. Trypanosomiasis incidence rates in a herd of local cattle …

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Foraging Behavior And Life History Of The Stemborer Parasitoid Cotesia Flavipes (Hymenoptera: Braconidae), R. P.J. Potting, W. A. Overholt, F. O. Danso, K. Takasu Jan 1997

Foraging Behavior And Life History Of The Stemborer Parasitoid Cotesia Flavipes (Hymenoptera: Braconidae), R. P.J. Potting, W. A. Overholt, F. O. Danso, K. Takasu

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The gregarious parasitoid Cotesia flavipes (Hymenoptera: Braconidae) attacks larvae of pyralid and noctuid stemborers by entering the stemborer tunnel. The short-range foraging behavior of female C. flavipes was studied on stemborer-infested plants, in patches with host-related products and in artificial transparent tunnels. In addition, the longevity under specific conditions and the potential and realized fecundity of female C. flavipes were determined. Larval frass, caterpillar regurgitate, and holes in the stem are used in host location by C. flavipes. The response to host products by C. flavipes seems not to be host species specific. Female C. flavipes respond to frass from …

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Geographic Variation In Host Selection Behaviour And Reproductive Success In The Stemborer Parasitoid Cotesia Flavipes (Hymenoptera: Braconidae), R. P.J. Potting, L. E.M. Vet, W. A. Overholt Jan 1997

Geographic Variation In Host Selection Behaviour And Reproductive Success In The Stemborer Parasitoid Cotesia Flavipes (Hymenoptera: Braconidae), R. P.J. Potting, L. E.M. Vet, W. A. Overholt

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Local parasitoid populations may be adapted to their sympatric major plant host complex. Parasitoid strains may thus differ in their propensity to search for a particular micro-habitat or host or they may differ in their physiological compatibility with particular plant or host species. Cotesiaflavipes Cameron, a larval parasitoid used worldwide in biological control against tropical stemborers, has a wide host range in diverse habitats. The existence of plant and/or host specific strains in C. flavipes has been postulated. To provide insight into the existence of strains in C. flavipes, we compared the plant/host complex selection behaviour, and physiological compatibility with …

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