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Full-Text Articles in Life Sciences

Spider Heuristics, Fiona R. Cross, Robert R. Jackson May 2005

Spider Heuristics, Fiona R. Cross, Robert R. Jackson

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Simple heuristics may help explain how even a spider, despite its minute brain, can be disturbingly intelligent. Hutchinson and Gigerenzer suggest that the generalist-specialist distinction (or more accurately the predictability-unpredictability distinction) may be related to a species' level of reliance on simple heuristics, and spider behaviour may present some especially instructive opportunities for investigating these ideas. Daniel Dennett's distinction between Darwinian, Skinnerian and Popperian animals might be useful for discerning the different contexts in which optimality considerations and individual decision making are relevant. © 2005 Elsevier B.V. All rights reserved.

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Rhabditis (Oscheius) Colombiana N. Sp. (Nematoda: Rhabditidae), A Necromenic Associate Of The Subterranean Burrower Bug Cyrtomenus Bergi (Hemiptera: Cydnidae) From The Cauca Valley, Colombia, S. Patricia Stock, Ana M. Caicedo, Paul A. Calatayud May 2005

Rhabditis (Oscheius) Colombiana N. Sp. (Nematoda: Rhabditidae), A Necromenic Associate Of The Subterranean Burrower Bug Cyrtomenus Bergi (Hemiptera: Cydnidae) From The Cauca Valley, Colombia, S. Patricia Stock, Ana M. Caicedo, Paul A. Calatayud

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Rhabditis (Oscheius) colombiana n. sp. is described as a necromenic associate of the burrower bug Cyrtomenus bergi (Hemiptera: Cydnidae) collected in the Cauca Valley, Colombia. The new species resembles others of the insectivora-group, viz, Rhabditis (O.) insectivora Körner, 1954 and Rhabditis (O.) lucianii Maupas, 1919, in a number of morphological and life history traits, but can be separated by a combination of morphological and morphometric characters. The most distinctive morphological features that separate R. (O.) colombiana n. sp. from these two Rhabditis species are the total size of both males and females, which are much shorter and slimmer in the …

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Fumigant Toxicity Of The Essential Oils Of Some African Plants Against Anopheles Gambiae Sensu Stricto, M. O. Omolo, D. Okinyo, I. O. Ndiege, W. Lwande, A. Hassanali Mar 2005

Fumigant Toxicity Of The Essential Oils Of Some African Plants Against Anopheles Gambiae Sensu Stricto, M. O. Omolo, D. Okinyo, I. O. Ndiege, W. Lwande, A. Hassanali

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The essential oils from 15 species of African plants selected by ethnobotanical considerations and field inspection (odour and presence of insects) were screened for fumigant toxicity to Anopheles gambiae s.s. in the laboratory. Essential oils from 6 species showed varying levels of toxicity, with Conyza newii (Compositae) and Plectranthus marruboides (Labiateae) being the most potent. Fifty compounds representing ∼74% of the essential oil of C. newii were identified by GC-MS and GC-coinjection (for available standards). The major and some of the minor constituents of the two oils were assayed at different doses. Two compounds, from C. newii, perillaldehyde and perillyl …

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Close-Range Host Searching Behavior Of The Stemborer Parasitoids Cotesia Sesamiae And Dentichasmias Busseolae: Influence Of A Non-Host Plant Melinis Minutiflora, Linnet S. Gohole, William A. Overholt, Zeyaur R. Khan, Louise E.M. Vet Mar 2005

Close-Range Host Searching Behavior Of The Stemborer Parasitoids Cotesia Sesamiae And Dentichasmias Busseolae: Influence Of A Non-Host Plant Melinis Minutiflora, Linnet S. Gohole, William A. Overholt, Zeyaur R. Khan, Louise E.M. Vet

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Studies were conducted on the host searching behavior of the larval parasitoid Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) and the pupal parasitoid Dentichasmias busseolae Heinrich (Hymenoptera: Ichneumonidae), both of which attack lepidopteran (Crambidae, Noctuidae) cereal stemborers. The behavior of D. busseolae was observed in a diversified habitat that consisted of stemborer host plants (maize, Zea mays L. and sorghum, Sorghum bicolor (L). Moench (Poaceae)) and a non-host plant (molasses grass, Melinis minutiflora Beauv. (Poaceae)), while C. sesamiae was observed separately on host plants and molasses grass. In previous olfactometer studies, C. sesamiae was attracted to molasses grass volatiles while D. busseolae …

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Location Of Stemborer Pupae In Various Host Plants And Implications For The Performance Of Natural Enemies With Emphasis On The Pupal Parasitoid Xanthopimpla Stemmator (Hymenoptera: Ichneumonidae), J. J. Muturi, A. J. Ngi-Song, F. Schulthess, J. M. Mueke, M. Sétamou Mar 2005

Location Of Stemborer Pupae In Various Host Plants And Implications For The Performance Of Natural Enemies With Emphasis On The Pupal Parasitoid Xanthopimpla Stemmator (Hymenoptera: Ichneumonidae), J. J. Muturi, A. J. Ngi-Song, F. Schulthess, J. M. Mueke, M. Sétamou

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In order to predict host accessibility by the pupal parasitoid Xanthopimpla stemmator (Thunberg), four grass species (Sorghum bicolor, Pennisetum purpureum, Sorghum arundinaceum and Zea mays) were sampled for stemborer pupae in Kwale, in the low altitudes of southern Kenya, and in Trans-Nzoia, in the high altitudes of western Kenya. The pupal position of Chilo orichalcociliellus (Strand), Chilo partellus (Swinhoe), Sesamia calamistis Hampson, Sesamia sp. nr oriaula (Tams and Bowden) and Busseola fusca (Fuller) in the plant were determined in relation to (a) the distance of pupae from the edge of the stem (depth), (b) the distance between the moth-exit hole …

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Comparative Performance Of The Mbita Trap, Cdc Light Trap And The Human Landing Catch In The Sampling Of Anopheles Arabiensis, An. Funestus And Culicine Species In A Rice Irrigation In Western Kenya, Evan M. Mathenge, Gedion O. Misiani, David O. Oulo, Lucy W. Irungu, Paul N. Ndegwa, Tom A. Smith, Gerry F. Killeen, Bart G.J. Knols Jan 2005

Comparative Performance Of The Mbita Trap, Cdc Light Trap And The Human Landing Catch In The Sampling Of Anopheles Arabiensis, An. Funestus And Culicine Species In A Rice Irrigation In Western Kenya, Evan M. Mathenge, Gedion O. Misiani, David O. Oulo, Lucy W. Irungu, Paul N. Ndegwa, Tom A. Smith, Gerry F. Killeen, Bart G.J. Knols

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Background: Mosquitoes sampling is an important component in malaria control. However, most of the methods used have several shortcomings and hence there is a need to develop and calibrate new methods. The Mbita trap for capturing host-seeking mosquitoes was recently developed and successfully tested in Kenya. However, the Mbita trap is less effective at catching outdoor-biting Anopheles funestus and Anopheles arabiensis in Madagascar and, thus, there is need to further evaluate this trap in diverse epidemiological settings. This study reports a field evaluation of the Mbita trap in a rice irrigation scheme in Kenya. Methods: The mosquito sampling efficiency of …

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Host Genotype By Parasite Genotype Interactions Underlying The Resistance Of Anopheline Mosquitoes To Plasmodium Falciparum, Louis Lambrechts, Jean Halbert, Patrick Durand, Louis C. Gouagna, Jacob C. Koella Jan 2005

Host Genotype By Parasite Genotype Interactions Underlying The Resistance Of Anopheline Mosquitoes To Plasmodium Falciparum, Louis Lambrechts, Jean Halbert, Patrick Durand, Louis C. Gouagna, Jacob C. Koella

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Background: Most studies on the resistance of mosquitoes to their malaria parasites focus on the response of a mosquito line or colony against a single parasite genotype. In natural situations, however, it may be expected that mosquito-malaria relationships are based, as are many other host-parasite systems, on host genotype by parasite genotype interactions. In such systems, certain hosts are resistant to one subset of the parasite's genotypes, while other hosts are resistant to a different subset. Methods: To test for genotype by genotype interactions between malaria parasites and their anopheline vectors, different genetic backgrounds (families consisting of the F1 offspring …

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Functional Response Of Six Indigenous Trichogrammatid Egg Parasitoids (Hymenoptera: Trichogrammatidae) In Kenya: Influence Of Temperature And Relative Humidity, Andrew Kalyebi, W. A. Overholt, F. Schulthess, J. M. Mueke, S. A. Hassan, S. Sithanantham Jan 2005

Functional Response Of Six Indigenous Trichogrammatid Egg Parasitoids (Hymenoptera: Trichogrammatidae) In Kenya: Influence Of Temperature And Relative Humidity, Andrew Kalyebi, W. A. Overholt, F. Schulthess, J. M. Mueke, S. A. Hassan, S. Sithanantham

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Laboratory tests were conducted to evaluate the functional responses of six species/strains of native Kenyan trichogrammatids using the factitious pyralid host, Corcyra cephalonica, under different temperature and relative humidity regimes. The objective was to identify promising species/strains for controlling the noctuid Helicoverpa armigera, a serious pest of vegetables in Kenya. The six species/strains of Trichogramma and Trichogrammatoidea represented collections from low (<700 m), mid (between 700 and 1200 m) and high (>1200 m) altitude locations. They were compared for parasitisation rates at six temperatures (10, 15, 20, 25, 30 and 35°C) and two relative humidity levels (40-50% and 70-80%), at five host egg densities (6, 12, 18, 24, and …

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The Presence Of Plasmodium Falciparum Gametocytes In Human Blood Increases The Gravidity Of Anopheles Gambiae Mosquitoes, Heather M. Ferguson, Louis C. Gouagna, Peter Obare, Andrew F. Read, Hamza Babiker, John Githure, John C. Beier Jan 2005

The Presence Of Plasmodium Falciparum Gametocytes In Human Blood Increases The Gravidity Of Anopheles Gambiae Mosquitoes, Heather M. Ferguson, Louis C. Gouagna, Peter Obare, Andrew F. Read, Hamza Babiker, John Githure, John C. Beier

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We conducted a field study in an area of endemic malaria transmission in western Kenya to determine whether mosquitoes that feed on gametocyte-infected blood but do not become infected have reduced or enhanced fecundity in comparison to mosquitoes fed on uninfected blood. Fifteen paired membrane-feeding experiments were conducted in which two strains of Anopheles gambiae mosquitoes were simultaneously fed on either Plasmodium falciparum-infected blood from children or uninfected control blood from adults. The presence of noninfecting gametocytes in blood increased the probability that An. gambiae would produce eggs after one blood meal by sixfold (odds ratio for control relative to …

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El Niño Causes Dramatic Outbreak Of Paederus Dermatitis In East Africa, Ingeborg M.C.J. Van Schayk, Ruben O. Agwanda, John I. Githure, John C. Beier, Bart G.J. Knols Jan 2005

El Niño Causes Dramatic Outbreak Of Paederus Dermatitis In East Africa, Ingeborg M.C.J. Van Schayk, Ruben O. Agwanda, John I. Githure, John C. Beier, Bart G.J. Knols

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An outbreak of Paederus sabaeus rove beetles in Kenya during the 1997-1998 El Niño resulted in a dramatic increase of vesicular dermatitis in its capital Nairobi. The beetle, popularly called ‘Nairobi Fly’, contains a potent toxic fluid that causes epidermolysis and acute conjunctivitis. A cross-sectional epidemiological study involving 1,208 Nairobi residents was conducted to determine the health impact of this outbreak. The results showed that one-third of the Nairobi population were infected during this period. The majority of the respondents reported lesions on exposed body parts above the shoulders. Disfiguring, painful blisters and skin rashes in and around the facial …

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Effect Of Agroecosystem Diversity On Natural Enemies Of Maize Stemborers In Coastal Kenya, C. A.O. Midega, C. K.P.O. Ogol, W. A. Overholt Dec 2004

Effect Of Agroecosystem Diversity On Natural Enemies Of Maize Stemborers In Coastal Kenya, C. A.O. Midega, C. K.P.O. Ogol, W. A. Overholt

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A study was conducted at Mtwapa in the northern coastal area of Kenya during the long and short rainy seasons of 1999 and 2000 to assess the benefits of agroecosystem diversification-through agroforestry and intercropping-on the activity of natural enemies of maize stemborers. Treatments consisted of maize and cowpea intercrops or maize monocrops planted within hedgerows of Leucaena leucocephala and Gliricidia sepium. The plots were mulched or unmulched and insecticide-treated or not. The maize stemborers encountered, in order of abundance, were Chilo partellus, Chilo orichalcociliellus and Sesamia calamistis. The egg parasitoids Trichogramma spp. and Telenomus spp. were recovered from stemborer eggs. …

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Laboratory Evaluation Of Some Eastern African Meliaceae As Sources Of Larvicidal Botanicals For Anopheles Gambiae, Mary Ndung'u, Baldwyn Torto, Bart G.J. Knols, Ahmed Hassanali Dec 2004

Laboratory Evaluation Of Some Eastern African Meliaceae As Sources Of Larvicidal Botanicals For Anopheles Gambiae, Mary Ndung'u, Baldwyn Torto, Bart G.J. Knols, Ahmed Hassanali

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Root bark extracts of five Meliaceae species (Turraea abyssinica Hochst., Turraea wakefeldii Oliv., Turraea mombassana Hiern ex C.DC., Trichilia roka (Forsk) Chiov. and Melia volkensii Guerke.) and different fractions thereof (following chloroform extraction and column chromatographic separation) were compared for their immediate toxicity and long-term effects on Anopheles gambiae Giles sensu stricto (Diptera: Culicidae). Larvicidal effects of the extracts appeared to be largely associated with limonoids of medium polarity with M. volkensii and T. mombassana extracts being more potent than those of the other Meliaceae. Long-term (6-8 days post-exposure) observations at lower doses showed that 100% cumulative mortality can be …

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Phlebotomine Sandflies (Diptera: Psychodidae) Collected In Mukusu, Machakos District, Kenya And Their Nocturnal Flight Activity, Eiko Kan, Christopher O. Anjili, Rajindar K. Saini, Toshitaka Hidaka, John I. Githure Nov 2004

Phlebotomine Sandflies (Diptera: Psychodidae) Collected In Mukusu, Machakos District, Kenya And Their Nocturnal Flight Activity, Eiko Kan, Christopher O. Anjili, Rajindar K. Saini, Toshitaka Hidaka, John I. Githure

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This is the first report on the nocturnal flight activity of the phlebotomine sandflies in the field by trap collection in Mukusu, Masinga, the kala-azar (visceral leishmaniasis in humans) area in Kenya. A total of 514 sandflies were collected with three different types of traps (sticky traps, CDC light traps and a goat-baited trap), and seven species of two genera (Sergentomyia and Phlebotomus) were identified. The number of Sergentomyia bedfordi Newstead individuals captured was the largest among these seven species. This suggests that S. bedfordi is the most common among the seven species in Mukusu. The result of the sticky …

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Performance Of Cotesia Flavipes (Hymenoptera: Braconidae) In Parasitizing Chilo Partellus (Lepidoptera: Crambidae) As Affected By Temperature And Host Stage, Nanqing Jiang, Mamoudou Sétamou, Adèle J. Ngi-Song, Charles O. Omwega Oct 2004

Performance Of Cotesia Flavipes (Hymenoptera: Braconidae) In Parasitizing Chilo Partellus (Lepidoptera: Crambidae) As Affected By Temperature And Host Stage, Nanqing Jiang, Mamoudou Sétamou, Adèle J. Ngi-Song, Charles O. Omwega

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The braconid larval parasitoid, Cotesia flavipes, is used as a biological control agent against the crambid Chilo partellus, a serious pest of cereal crops in eastern and southern Africa. We examined the survival, development parameters, and body growth patterns of the host and its parasitoid at different temperatures (22, 26, and 30°C) using third and fourth instars of Ch. partellus. For non-parasitized hosts, larval mortality tended to be highest at lowest temperature and for parasitized at third host instars only at highest temperature. Development time of Co. flavipes immatures significantly decreased with host instar and with temperature. Sex ratio of …

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The Development Of Plasmodium Falciparum In Experimentally Infected Anopheles Gambiae (Diptera: Culicidae) Under Ambient Microhabitat Temperature In Western Kenya, Bernard A. Okech, Louis C. Gouagna, Elizabeth Walczak, Ephantus W. Kabiru, John C. Beier, Guiyun Yan, John I. Githure Oct 2004

The Development Of Plasmodium Falciparum In Experimentally Infected Anopheles Gambiae (Diptera: Culicidae) Under Ambient Microhabitat Temperature In Western Kenya, Bernard A. Okech, Louis C. Gouagna, Elizabeth Walczak, Ephantus W. Kabiru, John C. Beier, Guiyun Yan, John I. Githure

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The effect of microhabitat temperature variation on the early development of Plasmodium falciparum in experimentally infected Anopheles gambiae s.s. (Diptera: Culicidae) was studied. Batches of mosquitoes were fed artificially on gametocyteamic blood obtained from human volunteers and then held in five environmental conditions described as: (1) incubator maintained at constant temperature of 28 ± 1°C as control; (2) temperature unregulated laboratory environment; (3) screen house; (4) grass thatched mud house and (5) corrugated iron roofed mud house. Both the grass and iron roofed mud houses were real houses found in the village communities around the ICIPE Research Centre in Mbita …

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Repellency Of Essential Oils Of Some Kenyan Plants Against Anopheles Gambiae, Maurice O. Omolo, Denis Okinyo, Isaiah O. Ndiege, Wilber Lwande, Ahmed Hassanali Oct 2004

Repellency Of Essential Oils Of Some Kenyan Plants Against Anopheles Gambiae, Maurice O. Omolo, Denis Okinyo, Isaiah O. Ndiege, Wilber Lwande, Ahmed Hassanali

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Five mosquito repellents have been identified from the essential oils of 6 plants growing in Kenya. These include (S)-(-)-cis-perillyl alcohol, (S)-(-)-cis-verbenol, (S)-(-)-cis-carveol, (S)-(-)-perillaldehyde, caryophyllene oxide and (S)-(-)-cis-perillyl alcohol. (S)-(-)-cis-perillyl alcohol and (S)-(-)-cis-verbenol were the most potent. Essential oils of six plants growing in Kenya were screened for repellent activities against Anopheles gambiae sensu stricto. The oils of Conyza newii (Compositeae) and Plectranthus marrubioides (Labiateae) were the most repellent (RD 50 = 8.9 × 10 -5 mg cm -2, 95% CI) followed by Lippia javanica (Verbenaceae), Lippia ukambensis (Verbenaceae), Tetradenia riparia, (Iboza multiflora) (Labiateae) and Tarchonanthus camphoratus (Compositeae). Eight constituents of …

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Influence Of Indoor Microclimate And Diet On Survival Of Anopheles Gambiae S.S. (Diptera: Culicidae) In Village House Conditions In Western Kenya, Bernard A. Okech, Louis C. Gouagna, Bart G.J. Knols, Ephantus W. Kabiru, Gerry F. Killeen, John C. Beier, Guiyun Yan, John I. Githure Sep 2004

Influence Of Indoor Microclimate And Diet On Survival Of Anopheles Gambiae S.S. (Diptera: Culicidae) In Village House Conditions In Western Kenya, Bernard A. Okech, Louis C. Gouagna, Bart G.J. Knols, Ephantus W. Kabiru, Gerry F. Killeen, John C. Beier, Guiyun Yan, John I. Githure

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The survival of female Anopheles gambiae s.s. mosquitoes inside two village house types (grass-thatched and iron-roofed) was studied in relation to diet and ambient indoor microclimatic conditions. Two batches of 20-30, 1-day-old laboratory-bred mosquitoes were maintained inside cages in the grass-thatched (n = 2) and iron-roofed (n = 2) houses and fed daily, one group on 10% glucose and the other on human blood. Throughout the experiments, indoor temperature and relative humidity of the houses were recorded, and mortality of mosquitoes monitored daily until all had died. The experiments were replicated thrice. There was no significant variation in the overall …

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Genetic Diversity In Cowpea [Vigna Unguiculata (L.) Walp.] As Revealed By Rapd Markers, Fana Sylla Ba, Remy S. Pasquet, Paul Gepts Aug 2004

Genetic Diversity In Cowpea [Vigna Unguiculata (L.) Walp.] As Revealed By Rapd Markers, Fana Sylla Ba, Remy S. Pasquet, Paul Gepts

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The present study, using RAPD analysis, was undertaken to characterize genetic variation in domesticated cowpea and its wild progenitor, as well as their relationships. The materials used consisted of 26 domesticated accessions, including accessions from each of the five cultivar-group, and 30 wild/weedy accessions, including accessions from West, East and southern Africa. A total of 28 primers generated 202 RAPD bands. One hundred and eight bands were polymorphic among the domesticated compared to 181 among wild/weedy cowpea accessions. Wild accessions were more diverse in East Africa, which is the likely area of origin of V. unguiculata var. spontanea. Var. spontanea …

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Multi-Trophic Level Interactions In A Cassava-Maize Mixed Cropping System In The Humid Tropics Of West Africa, F. Schulthess, A. Chabi-Olaye, S. Gounou Jun 2004

Multi-Trophic Level Interactions In A Cassava-Maize Mixed Cropping System In The Humid Tropics Of West Africa, F. Schulthess, A. Chabi-Olaye, S. Gounou

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Multi-trophic level interactions in a mixed crop, involving cassava and maize, were studied in derived-savanna in Benin, West Africa. Two trials were planted, one during the short rainy season two months before onset of the dry season and one during the long rainy season in spring. Key pests under study on maize were the noctuid Sesamia calamistis Hampson and the pyralids Eldana saccharina Walker and Mussidia nigrivenella Ragonot, and on cassava, the exotic mealybug, Phenacoccus manihoti Matile-Ferrero and its encyrtid parasitoid Apoanagyrus lopezi De Santis. Both crops received insecticide treatments to assess the crop loss by a pest species. On …

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Characterization Of Potential Larval Habitats For Anopheles Mosquitoes In Relation To Urban Land-Use In Melindi, Kenya, Joseph Keating, Kate Macintyre, Charles M. Mbogo, John I. Githure, John C. Beier May 2004

Characterization Of Potential Larval Habitats For Anopheles Mosquitoes In Relation To Urban Land-Use In Melindi, Kenya, Joseph Keating, Kate Macintyre, Charles M. Mbogo, John I. Githure, John C. Beier

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Background: This study characterized Anopheles mosquito larval habitats in relation to ecological attributes about the habitat and community-level drainage potential, and investigated whether agricultural activities within or around urban households increased the probability of water body occurrence. Malindi, a city on the coast of Kenya, was mapped using global positioning system (GPS) technology, and a geographic information system (GIS) was used to overlay a measured grid, which served as a sampling frame. Grid cells were stratified according to the level of drainage in the area, and 50 cells were randomly selected for the study. Cross-sectional household and entomological surveys were …

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Comparative Studies On The Infectivity Of Theileria Parva In Ticks Fed In Vitro And Those Fed On Cattle, Joseph M. Musyoki, Ellie O. Osir, Henry K. Kiara, Elizabeth D. Kokwaro Apr 2004

Comparative Studies On The Infectivity Of Theileria Parva In Ticks Fed In Vitro And Those Fed On Cattle, Joseph M. Musyoki, Ellie O. Osir, Henry K. Kiara, Elizabeth D. Kokwaro

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Nymphs of the brown ear tick, Rhipicephalus appendiculatus, were fed on heparinised bovine blood infected with Theileria parva parasites in an in vitro feeding system consisting of rabbit skin membranes. The main feeding and development parameters such as the mean attachment rate, feeding duration and engorgement weights of membrane-fed ticks were not significantly different from nymphs fed on cattle. The moulting rate was also comparable although a slight significant difference was observed. Assessment of infection prevalence and abundance with T. parva in adults indicated that the membrane-fed ticks acquired infection to the same level as those fed on cattle. Stabilates …

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Effect Of Constant Temperatures On Germination, Radial Growth And Virulence Of Metarhizium Anisopliae To Three Species Of African Tephritid Fruit Flies, Susan Dimbi, Nguya K. Maniania, Slawomir A. Lux, Jones M. Mueke Feb 2004

Effect Of Constant Temperatures On Germination, Radial Growth And Virulence Of Metarhizium Anisopliae To Three Species Of African Tephritid Fruit Flies, Susan Dimbi, Nguya K. Maniania, Slawomir A. Lux, Jones M. Mueke

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The effect of temperature on conidial germination, mycelial growth, and susceptibility of adults of three tephritid fruit flies, Ceratitis capitata (Wiedemann), C. fasciventris (Bezzi) and C. cosyra (Walker) to six isolates of Metarhizium anisopliae were studied in the laboratory. There were significant differences among the isolates in the effect of temperature on both germination and growth. Over 80% of conidia germinated at 20, 25 and 30°C, while between 26 and 67% conidia germinated at 35°C and less than 10% at 15°C within 24 hours. Radial growth was slow at 15°C and 35°C with all of the isolates. The optimum temperature …

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Host Suitability And Thermal Requirements Of Lathromeris Ovicida Risbec (Hymenoptera: Tricliogrammatidae), An Egg Parasitoid Of Cereal Stemborers In Africa, A. Chabi-Olaye, M. K. Fiaboe, F. Schulthess Jan 2004

Host Suitability And Thermal Requirements Of Lathromeris Ovicida Risbec (Hymenoptera: Tricliogrammatidae), An Egg Parasitoid Of Cereal Stemborers In Africa, A. Chabi-Olaye, M. K. Fiaboe, F. Schulthess

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Factors affecting the bionomics of the trichogrammatid egg parasitoid Lathromeris ovicida and its association with the two sympatric scelionid egg parasitoids Telenomus busseolae and Telenomus isis were studied in the laboratory. The potential host species employed were the noctuids Sesamia calamistis and Sesamia botanephaga, and the pyralids Eldana saccharina and Mussidia nigrivenella. Using eggs of S. calamistis Hampson as hosts, the lower and upper thresholds for development were estimated at 14.8 and 34°C, respectively. The percent parasitism, total progeny, and sex ratio decreased gradually from 42.0 to 10.2, from 56.4 to 10.8, and from 0.74 to 0.61, respectively, with host …

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Phylogeny And Biogeography Of Wajira (Leguminosae): A Monophyletic Segregate Of Vigna Centered In The Horn Of Africa Region, Mats Thulin, Matt Lavin, Remy Pasquet, Alfonso Delgado-Salinas Jan 2004

Phylogeny And Biogeography Of Wajira (Leguminosae): A Monophyletic Segregate Of Vigna Centered In The Horn Of Africa Region, Mats Thulin, Matt Lavin, Remy Pasquet, Alfonso Delgado-Salinas

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Evidence from chloroplast trnK and nuclear ribosomal ITS sequences and morphological data reveals that the monotypic legume genus Wajira is nested within a clade comprising the species of Vigna subgen. Macrorhynchus. This Wajira-containing clade is basally branching in a larger clade that contains many of the genera traditionally referred to as tribe Phaseoleae subtribe Phaseolinae. Wajira is thus recircumscribed to include Vigna subgen. Macrorhynchus. Given the heterogeneity of floral morphology of its constituent species, Wajira is apomorphically diagnosed by woody stems and a pollen brush that comprises an introrse linear array of unicellular hairs. This recircumscribed genus now comprises five …

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Host Species, Age And Sex As Factors Affecting The Susceptibility Of The African Tephritid Fruit Fly Species, Ceratitis Capitata, C. Cosyra And C. Fasciventris To Infection By Metarhizium Anisopliae, S. Dimbi, N. K. Maniania, S. A. Lux, J. M. Mueke Oct 2003

Host Species, Age And Sex As Factors Affecting The Susceptibility Of The African Tephritid Fruit Fly Species, Ceratitis Capitata, C. Cosyra And C. Fasciventris To Infection By Metarhizium Anisopliae, S. Dimbi, N. K. Maniania, S. A. Lux, J. M. Mueke

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The effect of host age and sex on the susceptibility of 3 tephritid fruit fly species, Ceratitis capitata (Wiedemann), C. cosyra (Walker) and C. fasciventris (Bezzi) to the entomopathogenic fungus Metarhizium anisopliae (Metchnikoff) Sorokin was studied in the laboratory. Three adult host ages, 0 (<1 day-old), 7-day-old and 14-day-old, were used. All 3 species were susceptible to fungal infection, although there were differences in the levels of susceptibility among the hosts. Age accounted for the largest variability in mortality followed by species, while sex had the lowest variability. Of the 3 host ages tested, the 0- and 7-day-old flies were more susceptible to fungal infection than the 14-day-old flies. Male and female C. fasciventris flies generally succumbed earlier to fungal infection than the other two species. Female flies of C. cosyra and C. fasciventris were also generally more susceptible to fungal infection than the males, although differences were apparent at 3 and 4 days after treatment but not 5 days after treatment. Age accounted for the largest variability in lethal time mortality values (LTs). Mean LT-values generally indicated that the speed of kill was faster among younger flies than the older flies. LT95 ranged between 3.9-4.9 days in the 0-day-old flies, 4.3-6.1 days in the 7-day-old flies and 4.6-6.1 days in 14-day-old flies in the different species and sexes. The implication of this study for the management of fruit flies is discussed.

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Responses Of Glossina Morsitans Morsitans To Blends Of Electroantennographically Active Compounds In The Odors Of Its Preferred (Buffalo And Ox) And Nonpreferred (Waterbuck) Hosts, Nicholas K. Gikonyo, Ahmed Hassanali, Peter G.N. Njagi, Rajinder K. Saini Oct 2003

Responses Of Glossina Morsitans Morsitans To Blends Of Electroantennographically Active Compounds In The Odors Of Its Preferred (Buffalo And Ox) And Nonpreferred (Waterbuck) Hosts, Nicholas K. Gikonyo, Ahmed Hassanali, Peter G.N. Njagi, Rajinder K. Saini

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In a previous study, comparison of the behavior of teneral Glossina morsitans morsitans on waterbuck, Kobus defassa (a refractory host), and on two preferred hosts, buffalo, Syncerus caffer, and ox, Bos indicus, suggested the presence of allomones in the waterbuck odor. Examination of the volatile odors by coupled gas chromatography-electroantennographic detection showed that the antennal receptors of the flies detected constituents common to the three bovids (phenols and aldehydes), as well as a series of compounds specific to waterbuck, including C8 - C13 methyl ketones, δ-octalactone, and phenols. In this study, behavioral respones of teneral G. m. morsitans to different …

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Parameter Estimation For Distributed Delay Based Population Models From Laboratory Data: Egg Hatching Of Oulema Duftschmidi Redthenbacher (Coleoptera, Chrysomelidae) As An Example, Maurizio Severini, Johann Baumgärtner, Lidia Limonta Sep 2003

Parameter Estimation For Distributed Delay Based Population Models From Laboratory Data: Egg Hatching Of Oulema Duftschmidi Redthenbacher (Coleoptera, Chrysomelidae) As An Example, Maurizio Severini, Johann Baumgärtner, Lidia Limonta

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The cohort development of poikilotherms under favorable temperature conditions may be described by the time-invariant distributed delay models that require three parameters, i.e. the thermal threshold T0, the thermal constant W and the variability parameter H representing distributed maturation times, also known as time distributed or stochastic development. Here, a parsimonious method is developed that uses stage-frequency matrices obtained under controlled conditions. The analysis of these matrices permits the estimation of the three parameters, while the incorporation of both developmental threshold and thermal constant into the time-invariant distributed delay model permits the representation of stochastic cohort development under constant temperatures. …

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Effect Of Soil Temperature And Moisture On Survival And Infectivity Of Metarhizium Anisopliae To Four Tephritid Fruit Fly Puparia, S. Ekesi, N. K. Maniania, S. A. Lux Jun 2003

Effect Of Soil Temperature And Moisture On Survival And Infectivity Of Metarhizium Anisopliae To Four Tephritid Fruit Fly Puparia, S. Ekesi, N. K. Maniania, S. A. Lux

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The infectivity of 4 isolates of Metarhizium anisopliae to puparia of Ceratitis capitata treated as late third-instar larvae in unsterilized soil was investigated in the laboratory under controlled temperature and moisture. At 20-30°C, mortality in puparia was highest at water potential of -0.1 and -0.01 mega Pascal (MPa) and lowest at water potential of -0.0055 and -0.0035 MPa in all the isolates. In wetter soil however, isolates ICIPE 20 and 60 caused significantly higher mortality than ICIPE 18 and 69. The survival of conidia in drier soil (-0.1 MPa) was not adversely affected at all temperatures. However, in wet soil …

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Crop Damage By Nematodes In Improved-Fallow Fields In Western Kenya, Serigne T. Kandji, Callistus K.P.O. Ogol, Alain Albrecht May 2003

Crop Damage By Nematodes In Improved-Fallow Fields In Western Kenya, Serigne T. Kandji, Callistus K.P.O. Ogol, Alain Albrecht

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The rotation of leguminous shrubs and crops is being tested on farms and recommended as a means of improving soil fertility and increasing crop yield in eastern and southern Africa, including western Kenya. However, this improved fallow practice may also increase the nematode population in the soil. An experiment was conducted to monitor the effects of plant-parasitic nematodes on crops after improved fallow. Soil was collected from a maize (Zea mays L.)/bean (Phaseolus vulgaris L.) field, a natural fallow, a Crotalaria (Crotalaria grahamiana Wight & Am.) fallow, a Tephrosia (Tephrosia vogelii Hook. f.) fallow and a Crotalaria - Tephrosia mixed …

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Prospects For Biological Control Of The Western Flower Thrips, Frankliniella Occidentalis, With The Entomopathogenic Fungus, Metarhizium Anisopliae, On Chrysanthemum, N. K. Maniania, S. Ekesi, B. Löhr, F. Mwangi May 2003

Prospects For Biological Control Of The Western Flower Thrips, Frankliniella Occidentalis, With The Entomopathogenic Fungus, Metarhizium Anisopliae, On Chrysanthemum, N. K. Maniania, S. Ekesi, B. Löhr, F. Mwangi

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The potential of Metarhizium anisopliae (Metsch.) Sorok. for the control of Frankliniella occidentalis (Pergande) on chrysanthemum cuttings was evaluated in greenhouse experiments. The fungus significantly reduced both the adult and larval populations of F. occidentalis, although the level of control of larval populations was much lower than for adults. Combined application of M. anisopliae and Methomyl (Lannate®), however, resulted in a significant reduction of both the larval and adult stages. The use of both control agents might be helpful in reducing the selection pressure for resistance to chemical insecticides, thereby delaying or preventing the build-up of resistant populations in greenhouses.

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