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Articles 1201 - 1230 of 1443

Full-Text Articles in Life Sciences

Evidence Of The Establishment Of Cotesia Flavipes (Hymenoptera: Braconidae), A Parasitoid Of Cereal Stemborers, And Its Host Range Expansion In Ethiopia, E. Getu, W. A. Overholt, E. Kairu, C. O. Omwega Apr 2003

Evidence Of The Establishment Of Cotesia Flavipes (Hymenoptera: Braconidae), A Parasitoid Of Cereal Stemborers, And Its Host Range Expansion In Ethiopia, E. Getu, W. A. Overholt, E. Kairu, C. O. Omwega

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Three lepidopteran cereal stemborers, Chilo partellus (Swinhoe) (Crambidae), Busseola fusca Fuller, and Sesamia calamistis Hampson (Noctuidae) were collected from maize and sorghum in Ethiopia. The noctuid stemborers are indigenous to Africa while C. partellus is an introduced species from Asia. In 1999, the Asian stemborer parasitoid, Cotesia flavipes Cameron (Braconidae) was found to be widespread in Ethiopia, even though it had never been released in the country. In addition to attacking Chilo partellus, Cotesia flavipes was reared from B. fusca and S. calamistis. The origin of C. flavipes in Ethiopia may have been Somalia where it was released in 1997 …

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Effects Of Molasses Grass, Melinis Minutiflora Volatiles On The Foraging Behavior Of The Cereal Stemborer Parasitoid, Cotesia Sesamiae, Linnet S. Gohole, William A. Overholt, Zeyaur R. Khan, John A. Pickett, Louise E.M. Vet Mar 2003

Effects Of Molasses Grass, Melinis Minutiflora Volatiles On The Foraging Behavior Of The Cereal Stemborer Parasitoid, Cotesia Sesamiae, Linnet S. Gohole, William A. Overholt, Zeyaur R. Khan, John A. Pickett, Louise E.M. Vet

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Olfactory responses of the cereal stemborer parasitoid Cotesia sesamiae to volatiles emitted by gramineous host and nonhost plants of the stemborers were studied in a Y-tube olfactometer. The host plants were maize (Zea mays) and sorghum (Sorghum bicolor), while the nonhost plant was molasses grass (Melinis minutiflora). In single-choice tests, females of C. sesamiae chose volatiles from infested and uninfested host plants and molasses grass over volatiles from the control (soil). In dual-choice tests, the wasp preferred volatiles from infested host plants to those from uninfested host plants. There was no discrimination between molasses grass volatiles and those of uninfested …

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Incomplete Sexual Isolation In Sympatry Between Subspecies Of The Butterfly Danaus Chrysippus (L.) And The Creation Of A Hybrid Zone, G. Lushai, D. A.S. Smith, I. J. Gordon, D. Goulson, J. A. Allen, N. Maclean Mar 2003

Incomplete Sexual Isolation In Sympatry Between Subspecies Of The Butterfly Danaus Chrysippus (L.) And The Creation Of A Hybrid Zone, G. Lushai, D. A.S. Smith, I. J. Gordon, D. Goulson, J. A. Allen, N. Maclean

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Subspecies chrysippus, dorippus and alcippus of the butterfly Danaus chrysippus differ at three biallelic colour gene loci. They have partially vicariant distributions, but their ranges overlap over a substantial part of central and East Africa, where hybridism is commonplace. We now report that the West African subspecies alcippus differs from other subspecies, not only in nuclear genotype but also in mitochondrial haplotype in both allopatry and sympatry. The maintenance of concordant nuclear and cytoplasmic genetic differences in sympatry, and in the face of hybridisation, is prima facie evidence for sexual isolation. Other evidence that suggests alcippus may be isolated from …

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Enrichment Of A Single Clone From A High Diversity Library Of Phage-Displayed Antibodies By Panning With Anopheles Gambiae (Diptera: Culicidae) Midgut Homogenate, G. F. Killeen, B. D. Foy, R. H. Frohn, D. Impoinvil, A. Williams, J. C. Beier Feb 2003

Enrichment Of A Single Clone From A High Diversity Library Of Phage-Displayed Antibodies By Panning With Anopheles Gambiae (Diptera: Culicidae) Midgut Homogenate, G. F. Killeen, B. D. Foy, R. H. Frohn, D. Impoinvil, A. Williams, J. C. Beier

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A high diversity library of recombinant human antibodies was selected on complex antigen mixtures from midguts of female Anopheles gambiae Giles. The library of phage-displayed single chain variable region fragment constructs, derived from β-lymphocyte mRNA of naïve human donors, was repeatedly selected and reamplified on the insoluble fraction of midgut homogenates. Five rounds of panning yielded only one midgut-specific clone, which predominated the resulting antibody panel. In A. gambiae, the epitope was found throughout the tissues of females but was absent from the midgut of males. The cognate antigen proved to be detergent soluble but very sensitive to denaturation and …

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Comparative Analysis Of Microsatellite Loci In Four Fruit Fly Species Of The Genus Ceratitis (Diptera: Tephritidae), F. N. Baliraine, M. Bonizzoni, E. O. Osir, S. A. Lux, F. J. Mulaa, L. Zheng, L. M. Gomulski, G. Gasperi, A. R. Malacrida Feb 2003

Comparative Analysis Of Microsatellite Loci In Four Fruit Fly Species Of The Genus Ceratitis (Diptera: Tephritidae), F. N. Baliraine, M. Bonizzoni, E. O. Osir, S. A. Lux, F. J. Mulaa, L. Zheng, L. M. Gomulski, G. Gasperi, A. R. Malacrida

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The possibility to cross-species amplify microsatellites in fruit flies of the genus Ceratitis was tested with the polymerase chain reaction (PCR) by analysing 23 Ceratitis capitata (Wiedemann) microsatellite markers on the genomic DNA of three other economically important, congeneric species: C. rosa (Karsch), C. fasciventris (Bezzi) and C. cosyra (Walker). Twenty-two primer pairs produced amplification products in at least one of the three species tested. The majority of the products were similar, if not identical in size to those expected in C. capitata. The structures of the repeat motifs and their flanking sequences were examined for a total of 79 …

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High Seasonal Variation In Entomologic Inoculation Rates In Eritrea, A Semi-Arid Region Of Unstable Malaria In Africa, Josephat Shililu, Tewolde Ghebremeskel, Solomon Mengistu, Helen Fekadu, Mehari Zerom, Charles Mbogo, John Githure, Robert Novak, Eugene Brantly, John C. Beier Jan 2003

High Seasonal Variation In Entomologic Inoculation Rates In Eritrea, A Semi-Arid Region Of Unstable Malaria In Africa, Josephat Shililu, Tewolde Ghebremeskel, Solomon Mengistu, Helen Fekadu, Mehari Zerom, Charles Mbogo, John Githure, Robert Novak, Eugene Brantly, John C. Beier

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Entomologic studies were conducted in eight villages to investigate the patterns of malaria transmission in different ecologic zones in Eritrea. Mosquito collections were conducted for 24 months between September 1999 and January 2002. The biting rates of Anopheles arabiensis were highly seasonal, with activity concentrated in the wet season between June and October in the highlands and western lowlands, and between December and March in the coastal region. The biting rates in the western lowlands were twice as high as in the western escarpment and 20 times higher than in the coastal region. Sporozoite rates were not significantly different among …

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Integrated Arthropod Pest Management Systems For Human Health Improvement In Africa, Johann Baumgärtner, Fritz Schulthess, Yunlong Xia Jan 2003

Integrated Arthropod Pest Management Systems For Human Health Improvement In Africa, Johann Baumgärtner, Fritz Schulthess, Yunlong Xia

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In a sub-Saharan African context, limited natural resources, infectious diseases, including those transmitted by arthropod vectors, and chronic exposure to food contaminated with mycotoxin-producing fungi which, among others, are vectored by insects, are among the major constraints to human health. Thus, pest control should be an important component in human health improvement projects. It appears that the advantages of preventive over curative methods are rarely recognised in Africa, with more emphasis being given to the search for the 'silver bullet' than to integrated control approaches. Integrated pest management (IPM) systems can be assigned to different decision-making levels as well as …

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Isoflavanones From The Allelopathic Aqueous Root Exudate Of Desmodium Uncinatum, Muniru K. Tsanuo, Ahmed Hassanali, Antony M. Hooper, Zeyaur Khan, Festus Kaberia, John A. Pickett, Lester J. Wadhams Jan 2003

Isoflavanones From The Allelopathic Aqueous Root Exudate Of Desmodium Uncinatum, Muniru K. Tsanuo, Ahmed Hassanali, Antony M. Hooper, Zeyaur Khan, Festus Kaberia, John A. Pickett, Lester J. Wadhams

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Three isoflavanones, 5,7,2′,4′ -tetrahydroxy-6-(3-methylbut-2-enyl)isoflavanone (1), 4″,5″ -dihydro-5,2′,4′-trihydroxy-5″-isopropenylfurano-(2″, 3″;7,6)-isoflavanone (2) and 4″,5″-dihydro-2′ -methoxy-5,4′-dihydroxy-5″-isopropenylfurano-(2″,3″;7,6) -isoflavanone (3) and a previously known isoflavone 5,7,4′ -trihydroxyisoflavone [genistein (4)] were isolated and characterised spectroscopically from the root exudate of the legume Desmodium uncinatum (Jacq.) DC. We propose the names uncinanone A, B, and C for compounds 1, 2 and 3, respectively. Isolated fractions containing uncinanone B (2) induced germination of seeds from the parasitic weed Striga hermonthica (Del.) Benth. and fractions containing uncinanone C (3) moderately inhibited radical growth, the first example of a newly identified potential allelopathic mechanism to prevent S. hermonthica parasitism. © 2003 …

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Spatial And Temporal Heterogeneity Of Anopheles Mosquitoes And Plasmodium Falciparum Transmission Along The Kenyan Coast, Charles M. Mbogo, Joseph M. Mwangangi, Joseph G. Nzovu, Weidong Gu, Guiyan Yan, James T. Gunter, Chris Swalm, Joseph Keating, James L. Regens, Josephat I. Shililu, John I. Githure, John C. Beier Jan 2003

Spatial And Temporal Heterogeneity Of Anopheles Mosquitoes And Plasmodium Falciparum Transmission Along The Kenyan Coast, Charles M. Mbogo, Joseph M. Mwangangi, Joseph G. Nzovu, Weidong Gu, Guiyan Yan, James T. Gunter, Chris Swalm, Joseph Keating, James L. Regens, Josephat I. Shililu, John I. Githure, John C. Beier

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The seasonal dynamics and spatial distributions of Anopheles mosquitoes and Plasmodium falciparum parasites were studied for one year at 30 villages in Malindi, Kilifi, and Kwale Districts along the coast of Kenya. Anopheline mosquitoes were sampled inside houses at each site once every two months and malaria parasite prevalence in local school children was determined at the end of the entomologic survey. A total of 5,476 Anopheles gambiae s.l. and 3,461 An. funestus were collected. Species in the An. gambiae complex, identified by a polymerase chain reaction, included 81.9% An. gambiae s.s., 12.8% An. arabiensis, and 5.3% An. merus. Anopheles …

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Effects Of Different Neem Formulations On The Twospotted Spider Mite, Tetranychus Urticae Koch, On Tomato (Lycopersicon Esculentum Mill.), Markus Knapp, Sophia Shaban Kashenge Jan 2003

Effects Of Different Neem Formulations On The Twospotted Spider Mite, Tetranychus Urticae Koch, On Tomato (Lycopersicon Esculentum Mill.), Markus Knapp, Sophia Shaban Kashenge

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The effects of four different neem formulations (Neemros®, Neemroc EC®, Neemroc Combi and Saroneem) and a combination of Neemros® with a synthetic acaricide (Mitac®) on the twospotted spider mite (Tetranychus urticae Koch) were compared with Mitac® on tomato (Lycopersicon esculentum Mill.) leaf discs in the laboratory. The following LC50 were determined: Neemroc EC® 12.9 ml/l, Saroneem 5.8 ml/l, Neemroc Combi 1.0 ml/l and Mitac® + Neemros® 1 ml/l + 17.6 g/l. No LC50 was determined for Neemros® since the highest mortality observed was 11.4%. The combination of Mitac® and Neemros® resulted in the highest mortality after 24 hours (83.3%), followed …

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Evidence For The Involvement Of A Tsetse Midgut Lectin-Trypsin Complex In Differentiation Of Bloodstream-Form Trypanosomes, L. U. Abubakar, G. Zimba, C. Wells, F. Mulaa, E. O. Osir Jan 2003

Evidence For The Involvement Of A Tsetse Midgut Lectin-Trypsin Complex In Differentiation Of Bloodstream-Form Trypanosomes, L. U. Abubakar, G. Zimba, C. Wells, F. Mulaa, E. O. Osir

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We have previously described a bloodmeal-induced molecule (lectin-trypsin complex) from the midgut of the tsetse fly, Glossina longipennis, with both lectin and trypsin activities (Osir et al., 1995). In this paper, we report on the isolation of a similar molecule from the midguts of Glossina fuscipes fuscipes and provide direct evidence for its involvement in the development of African trypanosomes. The molecule (native Mr ∼65,700) has two non-covalently linked subunits, Mr ∼28,800 and Mr ∼35,700. The native molecule was found to be capable of inducing differentiation of bloodstream-form trypanosomes into procyclic (midgut forms) in vitro. In the assays, specific antibodies …

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Screening Tomato (Lycopersicon Esculentum Mill.) Accessions For Resistance To The Twospotted Spider Mite Tetranychus Urticae Koch: Population Growth Studies, Markus Knapp, Debora Apiyo Mugada, Stephen Gaya Agong Jan 2003

Screening Tomato (Lycopersicon Esculentum Mill.) Accessions For Resistance To The Twospotted Spider Mite Tetranychus Urticae Koch: Population Growth Studies, Markus Knapp, Debora Apiyo Mugada, Stephen Gaya Agong

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The resistance of 63 tomato (Lycopersicon esculentum Mill.) accessions to the twospotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae), was investigated in screen house experiments and compared to Money Maker, a T. urticae-susceptible variety widely grown in Kenya. The number of motile mite stages 12 days after inoculation with 5 adult female mites was significantly lower than in the control variety (Money Maker) in seven accessions (Marglobe, Roma-VF, 94 RT 330, Continental Michel, Early Pearson, ARP 366-4 and 94 RT 316). Egg numbers were significantly lower than in the control in 14 accessions (Marglobe, Cal-J-VF, Roma-VF, Beauty, 95 RT 315, …

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Geographic Differences In Host Acceptance And Suitability Of Two Cotesia Sesamiae Populations In Zimbabwe, P. Chinwada, W. A. Overholt, C. O. Omwega, J. M. Mueke Jan 2003

Geographic Differences In Host Acceptance And Suitability Of Two Cotesia Sesamiae Populations In Zimbabwe, P. Chinwada, W. A. Overholt, C. O. Omwega, J. M. Mueke

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Three lepidopteran stemborers, Busseola fusca Fuller (Noctuidae), Sesamia calamistis Hampson (Noctuidae), and Chilo partellus (Swinhoe) (Crambidae), were evaluated for their acceptability for oviposition and suitability for development by two populations of the larval endoparasitoid Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) occurring in the highveld (>1200m) and lowveld (<600 m) regions of Zimbabwe. Mating studies were also conducted to determine reproductive compatibility between the populations. Both C. sesamiae populations preferred the noctuids to C. partellus for oviposition. possibly reflecting differences in evolutionary history. Although B. fusca was partially suitable for development of lowveld C. sesamiae, all three hosts were suitable for development of the highveld population. Crosses between highveld and lowveld C. sesamiae were compatible, and were generally not different from the intra-population crosses in developmental time, % adult emergence and sex ratio. However, broods were much larger when highveld males were used in the mating combinations. We conclude that although there is host overlap and probably a considerable degree of outbreeding between the two C. sesamiae populations, there are still significant genetic differences between them. Within Zimbabwe, it is unlikely that the deliberate introduction of either population outside its region of occurrence will give meaningful stemborer control. © 2003 Elsevier Science (USA). All rights reserved.

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Olfactory Responses Of Cotesia Flavipes (Hymenoptera: Braconidae) To Target And Non-Target Lepidoptera And Their Host Plants, Bekele Jembere, Adele J. Ngi-Song, W. Overholt Jan 2003

Olfactory Responses Of Cotesia Flavipes (Hymenoptera: Braconidae) To Target And Non-Target Lepidoptera And Their Host Plants, Bekele Jembere, Adele J. Ngi-Song, W. Overholt

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The attraction of Cotesia flavipes Cameron to volatiles from a range of non-target lepidopteran larvae and their host plants (grasses and trees) or food substrate (honeycomb) was evaluated using a Y-tube olfactometer. The non-target host larvae used in the study included Galleria mellonella (L.), Charaxes cithaeron Felder, Bombyx mori L., and Eldana saccharina Walker. The target insects, Chilo partellus (Swinhoe) and Chilo orichalcociliellus (Strand), were used as controls. Host plants included Afzelia quanzensis Welw., Morus alba L., Cyperus papyrus L., Pennisetum purpureum Schumach, and Zea mays L. The response of C. flavipes to volatiles from the non-target larvae and their …

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Ring A-Seco Mosquito Larvicidal Limonoids From Turraea Wakefieldii, Mary Ndung'u, Ahmed Hassanali, Antony M. Hooper, Sumesh Chhabra, Thomas A. Miller, Rowena L. Paul, Baldwyn Torto Jan 2003

Ring A-Seco Mosquito Larvicidal Limonoids From Turraea Wakefieldii, Mary Ndung'u, Ahmed Hassanali, Antony M. Hooper, Sumesh Chhabra, Thomas A. Miller, Rowena L. Paul, Baldwyn Torto

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Five novel limonoids, 1-5, were isolated from the root bark of Turraea wakefieldii and were characterized as tecleaninoid derivatives. This is the first report of the natural occurrence of tecleanin-type limonoids with a five-membered-ring A-seco structure for which we propose the name neotecleanins. The relative stereochemical structures of compounds 1-5 were established on the basis of NMR spectroscopy. The absolute stereochemical structure of 5 was confirmed by X-ray diffraction methods. In mosquito larvicidal assays, compounds 1, 2 and 4 showed dose-dependent larvicidal activity against larvae of Anopheles gambiae s.s. © 2003 Elsevier Ltd. All rights reserved.

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Host Specificity Of Psyttalia Cosyrae (Hymenoptera: Braconidae) And The Effect Of Different Host Species On Parasitoid Fitness, Samira A. Mohamed, William A. Overholt, Robert A. Wharton, Slawomir A. Lux, Elameen M. Eltoum Jan 2003

Host Specificity Of Psyttalia Cosyrae (Hymenoptera: Braconidae) And The Effect Of Different Host Species On Parasitoid Fitness, Samira A. Mohamed, William A. Overholt, Robert A. Wharton, Slawomir A. Lux, Elameen M. Eltoum

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Psyttalia cosyrae (Wilkinson) (Hymenoptera: Braconidae) is a synovigenic, koinobiont larval-pupal parasitoid of Ceratitis cosyra (Walker) (Diptera: Tephritidae), and possibly other tephritid fruit flies. Host acceptance and suitability of medfly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), mango fruit fly, Ceratitis cosyra, Natal fruit fly, Ceratitis rosa Karsch, Ceratitis fasciventris (Bezzi), Ceratitis anonae Graham, and melon fruit fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae), for oviposition and development of this parasitoid were investigated. The effect of different host species on traits widely used to assess parasitoid fitness was also evaluated. Psyttalia cosyrae accepted all host species tested, but acceptance varied. In no choice tests, …

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Malariasphere: A Greenhouse-Enclosed Simulation Of A Natural Anophelesgambiae (Diptera: Culicidae) Ecosystem In Western Kenya, Bart G.J. Knols, Basilio N. Njiru, Evan M. Mathenge, Wolfgang R. Mukabana, John C. Beier, Gerry F. Killeen Dec 2002

Malariasphere: A Greenhouse-Enclosed Simulation Of A Natural Anophelesgambiae (Diptera: Culicidae) Ecosystem In Western Kenya, Bart G.J. Knols, Basilio N. Njiru, Evan M. Mathenge, Wolfgang R. Mukabana, John C. Beier, Gerry F. Killeen

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Background: The development and implementation of innovative vector control strategies for malaria control in Africa requires in-depth ecological studies in contained semi-field environments. This particularly applies to the development and release of genetically-engineered vectors that are refractory to Plasmodium infection. Here we describe a modified greenhouse, designed to simulate a natural Anopheles gambiae Giles ecosystem, and the first successful trials to complete the life-cycle of this mosquito vector therein. Methods: We constructed a local house, planted crops and created breeding sites to simulate the natural ecosystem of this vector in a screen-walled greenhouse, exposed to ambient climate conditions, in western …

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Relative Safety Of Sprays Of Two Neem Insecticides To Diadegma Mollipla (Holmgren), A Parasitoid Of The Diamondback Moth: Effects On Adult Longevity And Foraging Behaviour, A. M. Akol, S. Sithanantham, P. G.N. Njagi, A. Varela, J. M. Mueke Nov 2002

Relative Safety Of Sprays Of Two Neem Insecticides To Diadegma Mollipla (Holmgren), A Parasitoid Of The Diamondback Moth: Effects On Adult Longevity And Foraging Behaviour, A. M. Akol, S. Sithanantham, P. G.N. Njagi, A. Varela, J. M. Mueke

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The non-target safety of two neem-based insecticides, Neemroc EC® (an oil formulation) and Neemros® (an oil-free powder formulation) to adults of Diadegma mollipla (Holmgren), a larval parasitoid of the diamondback moth, Plutella xylostella (L.), was investigated in laboratory bioassays. The neem insecticides were compared against Karate® (a synthetic pyrethroid insecticide) and water as sprays. Karate® caused 100% mortality in treated wasps within 6 h, while the two neem insecticides did not cause any significant mortality. The mean longevity of wasps was not significantly affected by exposure to the two neem insecticides. The time allocation to different components of foraging behaviour …

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Genetic Diversity Of The African Geocarpic Legume Kersting's Groundnut, Macrotyloma Geocarpum (Tribe Phaseoleae: Fabaceae), R. S. Pasquet, G. Mergeai, J. P. Baudoin Nov 2002

Genetic Diversity Of The African Geocarpic Legume Kersting's Groundnut, Macrotyloma Geocarpum (Tribe Phaseoleae: Fabaceae), R. S. Pasquet, G. Mergeai, J. P. Baudoin

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A survey of allozyme variation in Kersting's groundnut [Macrotyloma geocarpum (Harms) Maréchal and Baudet] was undertaken by examining 19 enzymes systems encoding 32 putative loci in 18 domesticated accessions and two wild accessions. No variation was found within and among domesticated accessions as well as within and between both wild accessions. However, very high genetic distance between wild and domesticated accessions suggests that they should be assigned to two different species. © 2002 Elsevier Science Ltd. All rights reserved.

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Morphology Of The Minute Larva Of Ptinella Tenella, With Special Reference To Effects Of Miniaturisation And The Systematic Position Of Ptiliidae (Coleoptera: Staphylinoidea), Vasily V. Grebennikov, Rolf G. Beutel Nov 2002

Morphology Of The Minute Larva Of Ptinella Tenella, With Special Reference To Effects Of Miniaturisation And The Systematic Position Of Ptiliidae (Coleoptera: Staphylinoidea), Vasily V. Grebennikov, Rolf G. Beutel

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External and internal features of minute reared ex ovo larvae of Ptinella tenella Erichson with the head widths ranging from 108 to 138 μm are described. In total 139 setae (trichoid sensilla), 18 pores (non-trichoid sensilla), and 60 muscles were identified. The complexity of the chaetotaxy, the musculature of the head, the tentorium, and the digestive tract are not affected by the extremely small size of the larvae. Specific features, which may have resulted from miniaturisation are the elongate shape of the brain reaching the mesothorax posteriorly, the reduced condition of the thoracic sclerites and endosternites, the simplified musculature of …

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The Development Of A Multipurpose Trap (The Nzi) For Tsetse And Other Biting Flies, S. Mihok Oct 2002

The Development Of A Multipurpose Trap (The Nzi) For Tsetse And Other Biting Flies, S. Mihok

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New trap designs for tsetse (Glossinidae), stable flies (Muscidae: Stomoxyinae), and horse flies (Tabanidae) were tested in Kenya to develop a multipurpose trap for biting flies. Many configurations and colour/fabric combinations were compared to a simplified, blue-black triangular trap to identify features of design and materials that result in equitable catches. New designs were tested against conventional traps, with a focus on Glossina pallidipes Austen and G. longipennis Corti, Stomoxys niger Macquart, and Atylotus agrestis (Wiedemann). A simple design based on minimal blue and black rectangular panels, for attraction and contrast, with a trap body consisting of an innovative configuration …

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Wolbachia Infection In Cotesia Sesamiae (Hymenoptera: Braconidae) Causes Cytoplasmic Incompatibility: Implications For Biological Control, Moses B. Mochiah, Adele J. Ngi-Song, William A. Overholt, Richard Stouthamer Sep 2002

Wolbachia Infection In Cotesia Sesamiae (Hymenoptera: Braconidae) Causes Cytoplasmic Incompatibility: Implications For Biological Control, Moses B. Mochiah, Adele J. Ngi-Song, William A. Overholt, Richard Stouthamer

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Cotesia sesamiae (Hymenoptera: Braconidae) is an indigenous, gregarious, larval endoparasitoid that attacks mid- to late-instar of the stem borer larvae. Although the parasitoid is distributed widely throughout Africa, not all local populations appear to be equally effective in controlling stem borers. Consequently, there is an interest in releasing the more effective strains in areas that already have very low populations of C. sesamiae. Some C. sesamiae populations are infected with bacterial symbionts in the genus Wolbachia, which may induce cytoplasmic incompatibility. Using an antibiotic treatment, we have established that the Wolbachia infection causes cytoplasmic incompatibility of the female mortality type …

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Control Of Witchweed Striga Hermonthica By Intercropping With Desmodium Spp., And The Mechanism Defined As Allelopathic, Zeyaur R. Khan, Ahmed Hassanali, William Overholt, Tsanuo M. Khamis, Antony M. Hooper, John A. Pickett, Lester J. Wadhams, Christine M. Woodcock Sep 2002

Control Of Witchweed Striga Hermonthica By Intercropping With Desmodium Spp., And The Mechanism Defined As Allelopathic, Zeyaur R. Khan, Ahmed Hassanali, William Overholt, Tsanuo M. Khamis, Antony M. Hooper, John A. Pickett, Lester J. Wadhams, Christine M. Woodcock

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During investigations into the control of insect damage to maize crops in subsistence farming in Kenya, which involved intercropping with repellent plants, the fodder legumes silverleaf (Desmodium uncinatum) and greenleaf (D. intortum) were also found to reduce dramatically the infestation of maize by parasitic witchweeds such as Striga hermonthica. This effect was confirmed by further field testing and shown to be significantly greater than that observed with other legumes, e.g., cowpea, as were the concomitant yield increases. The mechanism was investigated, and although soil shading and addition of nitrogen fertilizer showed some benefits against S. hermonthica infestation, a putative allelopathic …

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Repellency Of Live Potted Plants Against Anopheles Gambiae From Human Baits In Semi-Field Experimental Huts, Aklilu Seyoum, Ephantus W. Kabiru, Wilber Lwande, Gerry F. Killeen, Ahmed Hassanali, Bart G.J. Knols Aug 2002

Repellency Of Live Potted Plants Against Anopheles Gambiae From Human Baits In Semi-Field Experimental Huts, Aklilu Seyoum, Ephantus W. Kabiru, Wilber Lwande, Gerry F. Killeen, Ahmed Hassanali, Bart G.J. Knols

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The repellency of potted plants against the malaria vector Anopheles gambiae sensu stricto Giles was quantified in experimental huts under semi-field conditions inside a screen-walled greenhouse. Ocimum americanum Linnaeus (Labiatae), Lantana camara L. (Verbenaceae), and Lippia uckambensis Spreng (Verbenaceae) repelled at an average of 39.7% (95% confidence interval [CI] = 29.6-48.4%), 32.4% (95% CI = 19.7-43.1%), and 33.3% (95% CI = 21.5-43.3%) of the mosquitoes, respectively (P < 0.0001 for all treatments). This was determined by logistic regression, allowing for variations associated with different bait hosts, sampling huts, and replicate test nights. In contrast, Ocimum kilimandscharicum Guerke (Labiatae), Ocimum suave Willd. (Labiatae), Corymbia citriodora Hook (Myrtaceae), Azadirachta indica A. Juss (Meliaceae), Tagetes minuta L. (Asteraceae), and Hyptis suaveolens Poit. (Lamiaceae) did not significantly repel mosquitoes. The combination of O. americanum with either L. camara or L. uckambensis repelled 31.6% (95% CI = 19.7-41.7%) and 45.2% (95% CI = 34.7-54.0%) of the mosquitoes, respectively (P < 0.0001 for both treatments). This study is the first to show that live intact plants can reduce domestic exposure to malaria vector mosquitoes. As such, they may represent a new, sustainable and readily applicable malaria vector control tool for incorporation into integrated vector management programs.

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Ovicidal Activity Of Entomopathogenic Hyphomycetes To The Legume Pod Borer, Maruca Vitrata And The Pod Sucking Bug, Clavigralla Tomentosicollis, S. Ekesi, R. S. Adamu, N. K. Maniania Aug 2002

Ovicidal Activity Of Entomopathogenic Hyphomycetes To The Legume Pod Borer, Maruca Vitrata And The Pod Sucking Bug, Clavigralla Tomentosicollis, S. Ekesi, R. S. Adamu, N. K. Maniania

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The ovicidal activity of eight isolates of entomopathogenic hyphomycetes was evaluated in the laboratory against Maruca vitrata and Clavigralla tomentosicollis. At a concentration of 1 × 108 conidia ml-1, four isolates (Beauveria bassiana CPD 3 and 10, and Metarhizium anisopliae CPD 5 and 12) were found to be highly pathogenic to eggs of M. vitrata, achieving 89-100% mortality. At a given concentration, three isolates (B. bassiana CPD 9 and M. anisopliae CPD 5 and 12) were highly pathogenic to eggs of C. tomentosicollis, achieving 91-94% mortality. These isolates also caused high larval and nymphal mortality (94-100% in M. vitrata and …

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Visual Evaluation And Recognition Of Hosts By The Tick Parasitoid, Ixodiphagus Hookeri (Hymenoptera: Encyrtidae), F. A. Demas, E. N. Mwangi, A. Hassanali, E. C. Kunjeku, A. R. Mabveni Jul 2002

Visual Evaluation And Recognition Of Hosts By The Tick Parasitoid, Ixodiphagus Hookeri (Hymenoptera: Encyrtidae), F. A. Demas, E. N. Mwangi, A. Hassanali, E. C. Kunjeku, A. R. Mabveni

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The role of host size, movement, feeding status, color, and species in the visual host evaluation and recognition behavior of the tick parasitoid, Ixodiphagus hookeri Howard was investigated. Freshly emerged female parasitoids were subjected to a choice bioassay, where the test materials were placed in sealed vials and the vials placed in a Petri dish. When presented with A. variegatum live and mummified nymphs, females examined: larger nymphs significantly longer than smaller nymphs, fed nymphs significantly longer than unfed nymphs, dead and live nymphs for similar lengths of time, and grey live nymphs and yellow-brown and dark brown mummified nymphs …

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Extent Of Digestion Affects The Success Of Amplifying Human Dna From Blood Meals Of Anopheles Gambiae (Diptera: Culicidae), W. R. Mukabana, W. Takken, P. Seda, G. F. Killeen, W. A. Hawley, B. G.J. Knols Jun 2002

Extent Of Digestion Affects The Success Of Amplifying Human Dna From Blood Meals Of Anopheles Gambiae (Diptera: Culicidae), W. R. Mukabana, W. Takken, P. Seda, G. F. Killeen, W. A. Hawley, B. G.J. Knols

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The success of distinguishing blood meal sources of Anopheles gambiae Giles through deoxyribonucleic acid (DNA) profiling was investigated by polymerase chain reaction (PCR) amplification at the TC-11 and VWA human short tandem repeats (STR) loci. Blood meal size and locus had no significant effect on the success of amplifying human DNA from blood meals digested for 0, 8, 16, 24 and 32 h (P = 0.85 and 0.26 respectively). However, logistic regression found a significant negative relationship between time since ingestion and the success probability of obtaining positive PCR products among meals digested for between 8 and 32 h (P …

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Functional Response Of Orius Albidipennis (Hemiptera: Anthocoridae) To Megalurothrips Sjostedti (Thysanoptera: Thripidae), Linus M. Gitonga, W. A. Overholt, B. Löhr, J. K. Magambo, J. M. Mueke Jun 2002

Functional Response Of Orius Albidipennis (Hemiptera: Anthocoridae) To Megalurothrips Sjostedti (Thysanoptera: Thripidae), Linus M. Gitonga, W. A. Overholt, B. Löhr, J. K. Magambo, J. M. Mueke

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A locally available anthocorid predator, Orius albidipennis Reuter, was evaluated as a candidate biocontrol agent for Megalurothrips sjostedti Trybom, a major pest of French beans, Phaseolus vulgaris (L), in Kenya. The functional response of adult O. albidipennis to larval and adult M. sjostedti was studied at 15, 25, and 28°C and densities of 5, 10, 20, and 30 larval and adult M. sjostedti per cage, over 24 h. More larvae and adult M. sjostedti were killed at the higher densities and with an increase in temperature. The data provided good fit to both type I and II functional response models. …

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Evidence For A Compound In Comstock-Kellog Glands Modulating Premating Behavior In Male Desert Locust, Schistocerca Gregaria, Peter G.N. Njagi, B. Torto May 2002

Evidence For A Compound In Comstock-Kellog Glands Modulating Premating Behavior In Male Desert Locust, Schistocerca Gregaria, Peter G.N. Njagi, B. Torto

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The Comstock-Kellog glands in adult females of certain acridid species, including the desert locust, Schistocerca gregaria have been implicated as a source of volatiles that play a role in mating behavior. A dichloromethane extract of the glands was analyzed for metabolites by gas chromatography, coupled gas chromatography-electroantennographic detection, and mass spectrometry. Coupled gas chromatography-electroantennographic detector (GC-EAD) analysis revealed a component that elicited an electroantennogram response from the antenna of adult male S. gregaria. The compound was identified by GC-MS as pentanoic acid. The levels of the compound in the gland extract varied with age of female locust; it was present …

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Odor Composition Of Preferred (Buffalo And Ox) And Nonpreferred (Waterbuck) Hosts Of Some Savanna Tsetse Flies, Nicholas K. Gikonyo, Ahmed Hassanali, Peter G.N. Njagi, Peter M. Gitu, Jacob O. Midiwo May 2002

Odor Composition Of Preferred (Buffalo And Ox) And Nonpreferred (Waterbuck) Hosts Of Some Savanna Tsetse Flies, Nicholas K. Gikonyo, Ahmed Hassanali, Peter G.N. Njagi, Peter M. Gitu, Jacob O. Midiwo

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A previous study on the feeding responses of tsetse flies, Glossina morsitans morsitans, implicated the existence of allomonal barriers, both volatile and nonvolatile, on the nonpreferred host, waterbuck, Kobus defassa. In the present study, electroantennogram-active compounds in odors from waterbuck were compared with those of two preferred hosts of tsetse flies, buffalo, Syncerus caffer, and ox, Bos indicus. Odors from the three bovids were trapped on activated charcoal and/or reverse-phase (octadecyl bonded) silica and analyzed with a gas chromatography- linked electroantennographic detector (GC-EAD) and, where possible, identified by using gas chromatography-linked mass spectrometry (GC-MS) and chromatographic comparisons with authentic samples. …

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