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Articles 1021 - 1050 of 1129

Full-Text Articles in Entomology

Haemolymph Ecdysteroids And The Prothoracic Glands In The Solitary And Gregarious Adults Of Schistocerca Gregaria, Amer I. Tawfik, Anna Vedrová, Weiwei Li, František Sehnal, D. Obeng-Ofori May 1997

Haemolymph Ecdysteroids And The Prothoracic Glands In The Solitary And Gregarious Adults Of Schistocerca Gregaria, Amer I. Tawfik, Anna Vedrová, Weiwei Li, František Sehnal, D. Obeng-Ofori

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The haemolymph titre of ecdysteroids rises in the adults of both sexes to a brief peak in the first week after emergence. A major rise begins on days 8-10, coincidentally with intensive vitellogenesis in the females and aggregation pheromone production in the males. The titre reaches about 400 ng of 20-hydroxyecdysone (20E) equiv./ml in the solitary, but less than 150 ng/ml in the gregarious adults of both sexes. In the females, the titre drops after oviposition (prior to day 20) and remains low until the next egg batch matures; then it increases in either phase to 150-180 ng/ml. A similar …

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Seasonal Variation In The Essential Oil Composition Of Commiphora Quadricincta And Its Effect On The Maturation Of Immature Adults Of The Desert Locust, Schistocerca Gregaria, Y. O.H. Assad, B. Torto, A. Hassanali, P. G.N. Njagi, N. H.H. Bashir, H. Mahamat Mar 1997

Seasonal Variation In The Essential Oil Composition Of Commiphora Quadricincta And Its Effect On The Maturation Of Immature Adults Of The Desert Locust, Schistocerca Gregaria, Y. O.H. Assad, B. Torto, A. Hassanali, P. G.N. Njagi, N. H.H. Bashir, H. Mahamat

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Extracts of steam distillates of the desert shrub Commiphora quadricincta were tested for their effects on the maturation of gregarious immature males and females of the desert locust, Schistocerca gregaria. Maturation was significantly faster in immature adults exposed to the extract obtained before winter rains than in those exposed to the extract obtained after the rains, with respect to locust colour changes (yellowing of body), mating activity, aggregation-maturation pheromone titres (as measured by phenylacetonitrile levels in males), ovulation (as determined by the length of oocytes in females) and oviposition time. A large number of the compounds in the crude extracts …

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Identification Of Components Of The Oviposition Aggregation Pheromone Of The Gregarious Desert Locust, Schistocerca Gregaria (Forskal), M. M. Rai, A. Hassanali, R. K. Saini, H. Odongo, H. Kahoro Feb 1997

Identification Of Components Of The Oviposition Aggregation Pheromone Of The Gregarious Desert Locust, Schistocerca Gregaria (Forskal), M. M. Rai, A. Hassanali, R. K. Saini, H. Odongo, H. Kahoro

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Acetophenone and veratrole have been identified as two major behaviourally active components of the oviposition aggregation pheromone of the desert locust, Schistocerca gregaria. These compounds were identified from the volatiles of egg pod froth using gas chromatography-electroantennographic (GC-EAD) and gas chromatography-mass spectrometric (GC-MS) analysis. Both compounds were shown to elicit aggregation of gravid females in oviposition bioassays; however, they do not act synergistically. Both acetophenone and veratrole individually at optimum doses induced about 70% egg laying, a value similar to that evoked with froth volatiles.

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Cloning And Expression Of A Bacillus Thuringiensis (L1-2) Gene Encoding A Crystal Protein Active Against Glossina Morsitans Morsitans And Chilo Partellus, Edward O. Omolo, M. Diane James, Ellie O. Osir, Jennifer A. Thomson Feb 1997

Cloning And Expression Of A Bacillus Thuringiensis (L1-2) Gene Encoding A Crystal Protein Active Against Glossina Morsitans Morsitans And Chilo Partellus, Edward O. Omolo, M. Diane James, Ellie O. Osir, Jennifer A. Thomson

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A local isolate of Bacillus thuringiensis, designated L1-2, that is toxic to Chilo partellus was found to be toxic to the adult tsetse fly, Glossina morsitans morsitans. The δ-endotoxin crystals derived from the isolate gave a major protein band with a molecular weight of M(r) 130,000- 140,000 on denaturing polyacrylamide gel electrophoresis. The sequence of the cloned gene was found to be similar to that of the B. thuringiensis subsp. kurstaki HD-73 cryIA(c) gene, having one amino acid difference at position 148 and four additional DNA differences.

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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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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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Physiological Responses And Central Nervous Projections Of Antennal Olfactory Receptor Neurons In The Adult Desert Locust, Schistocerca Gregaria (Orthoptera: Acrididae), B. S. Hansson, S. A. Ochieng, X. Grosmaitre S Anton, P. G.N. Njagi Jan 1996

Physiological Responses And Central Nervous Projections Of Antennal Olfactory Receptor Neurons In The Adult Desert Locust, Schistocerca Gregaria (Orthoptera: Acrididae), B. S. Hansson, S. A. Ochieng, X. Grosmaitre S Anton, P. G.N. Njagi

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Olfactory receptor neurons present in two morphological sensillum types on the male Schistocerca gregaria antenna were for the first time investigated physiologically when stimulated with behaviourally relevant odours. Neurons present in trichoid/basiconic sensilla showed clear excitatory responses to compounds present in the male-produced aggregation pheromone and also to a plant produced compound. Sensilla could be categorised physiologically according to the responses of their receptor neurons to the tested stimuli. Also receptor neurons present in sensilla coeloconica responded to aggregation pheromone components, but always in an inhibitory fashion. These neurons could, however, be excited by a plant produced compound and by …

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Volatile Infochemicals Used In Host And Host Habitat Location By Cotesia Flavipes Cameron And Cotesia Sesamiae (Cameron) (Hymenoptera: Braconidae), Larval Parasitoids Of Stemborers On Graminae, Adele J. Ngi-Song, William A. Overholt, Peter G.N. Njagi, Marcel Dicke, Jonathan N. Ayertey, Wilbert Lwande Jan 1996

Volatile Infochemicals Used In Host And Host Habitat Location By Cotesia Flavipes Cameron And Cotesia Sesamiae (Cameron) (Hymenoptera: Braconidae), Larval Parasitoids Of Stemborers On Graminae, Adele J. Ngi-Song, William A. Overholt, Peter G.N. Njagi, Marcel Dicke, Jonathan N. Ayertey, Wilbert Lwande

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Female Cotesia flavipes Cameron and Cotesia sesamiae (Cameron) were attracted to odors in a Y-tube olfactometer from uninfested maize (Zea mays L.), sorghum [Sorghum bicolor (L.)]. and napier grass (Pennisetum purpureum Schumach). In dual choice tests. Cotesia flavipes showed a preference for maize over sorghum, while maize and napier grass were equally attractive. In contrast, Cotesia sesamiae preferred volatiles from sorghum and napier grass over those from maize. The two parasitoids were significantly more attracted to maize infested with the stemborers, Chilo partellus (Swinhoe), Chilo orichalcociliellus Strand, Sesamia calamistis Hampson, and Busseola fusca (Fuller), than uninfested maize. In dual choice …

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Oviposition Behavior Of Cotesia Flavipes And Goniozus Indicus, Larval Parasitoids Of The Lepidopteran Stemborer Chilo Partellus, Keiji Takasu, William A. Overholt Jan 1996

Oviposition Behavior Of Cotesia Flavipes And Goniozus Indicus, Larval Parasitoids Of The Lepidopteran Stemborer Chilo Partellus, Keiji Takasu, William A. Overholt

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Observing the opposition behavior of ingress-and-sting larval parasitoids of lepidopteran stemborers is difficult due to the cryptic feeding behavior of the hosts. A method for observing their opposition behavior was developed. An individual stemborer larva was introduced into a glass tube (0.7 cm in diameter; 7 cm in length) which contained a piece of maize stem (0.5-0.6 cm in diameter; 4-5 cm in length). The larva was allowed 14-20 h to feed on the maize and produce frass before introducing a single adult female parasitoid. Using this method, we observed the endoparasitoid Cotesia flavipes (CAMERON) and the ectoparasitoid Goniozus indicus …

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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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Chemoecological Role Of Mammalian Urine In Host Location By Tsetse, Glossina Spp. (Diptera: Glossinidae), L. Chuka Madubunyi, A. Hassanali, W. Ouma, D. Nyarango, J. Kabii Jan 1996

Chemoecological Role Of Mammalian Urine In Host Location By Tsetse, Glossina Spp. (Diptera: Glossinidae), L. Chuka Madubunyi, A. Hassanali, W. Ouma, D. Nyarango, J. Kabii

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Trap catch size was used to investigate whether Glossina pallidipes and G. longipennis could distinguish between the urine of the African buffalo, cattle, and waterbuck at Nguruman in southwest Kenya, NG2G traps baited with aged urine of these bovids caught significantly more of each tsetse than did the controls. The mean catch of either tsetse species in traps baited with aged urine of buffalo and cattle (tsetse hosts) and waterbuck (a nonhost) did not differ significantly. Aged urine from both tsetse hosts (buffalo and cattle) and the nonhost (waterbuck) was found to contain 4-cresol and 3-n-propylphenol in about the same …

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Identification Of Major Components Of Larviposition Pheromone From Larvae Of Tsetse Flies Glossina Morsitans Morsitans Westwood And Glossina Morsitans Centralis Machado, R. K. Saini, A. Hassanali, J. Andoke, P. Ahuya, W. P. Ouma Jan 1996

Identification Of Major Components Of Larviposition Pheromone From Larvae Of Tsetse Flies Glossina Morsitans Morsitans Westwood And Glossina Morsitans Centralis Machado, R. K. Saini, A. Hassanali, J. Andoke, P. Ahuya, W. P. Ouma

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The presence of pheromones produced by larvae of Glossina morsitans morsitans and G. m. centralis, respectively, which attract gravid females and result in aggregation of pupae, is confirmed. Behavioral experiments indicated that females preferred to larviposit over moist sand conditioned by previously allowing larvae to pupariate in it. Similar results were obtained with filter papers contaminated with the prepupariation excretions of larvae and with volatiles collected from larvae prior to pupariation. n-Pentadecane and n-dodecane were identified as the dominant electrophysiologically active components of the larviposition pheromones of G. m. morsitans and G. m. centralis, respectively, by GC-EAD and GC-MS analysis …

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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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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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Responses Of Nymphs Of Desert Locust, Schistocerca Gregaria To Volatiles Of Plants Used As Rearing Diet, Peter George N. Njagi, Baldwyn Torto Jan 1996

Responses Of Nymphs Of Desert Locust, Schistocerca Gregaria To Volatiles Of Plants Used As Rearing Diet, Peter George N. Njagi, Baldwyn Torto

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Gregarious nymphs of the desert locust, Schistocerca gregaria (Forsk.) (Orthoptera: Acrididae) were more attracted to volatiles from mechanically damaged food plants used for rearing than to either the undamaged or damaged food plants not used as diet in Y-tube olfactometer assays. Comparative analysis of the volatile emissions from plants used for rearing and food plants not used for rearing, e.g. Sorghum bicolor, Pennisetum clandestinum, Schouwia thebaica, wheat (Triticum sp., var. 'Nyangumi'), Zygophyllum simplex, Heliotropium undulatum and Tribulus terrestris was carried out by GC, GC-EAD and GC-MS. Significant quantitative and qualitative differences were found in the volatile emissions and olfactory responses …

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