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Articles 1141 - 1170 of 1443

Full-Text Articles in Life Sciences

Combined Control Of Striga Hermonthica And Stemborers By Maize-Desmodium Spp. Intercrops, Zeyaur R. Khan, John A. Pickett, Lester J. Wadhams, Ahmed Hassanali, Charles A.O. Midega Sep 2006

Combined Control Of Striga Hermonthica And Stemborers By Maize-Desmodium Spp. Intercrops, Zeyaur R. Khan, John A. Pickett, Lester J. Wadhams, Ahmed Hassanali, Charles A.O. Midega

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The African witchweed (Striga spp.) and lepidopteran stemborers are two major biotic constraints to the efficient production of maize in sub-Saharan Africa. Previous studies had shown the value of intercropping maize with Desmodium uncinatum in the control of both pests. The current study was conducted to assess the potential role of other Desmodium spp., adapted to different agro-ecologies, in combined control of both pests in Kenya. Treatments consisted of intercropped plots of a Striga hermonthica- and stemborer-susceptible maize variety and one Desmodium sp. or cowpea, with a maize monocrop plot included as a control. S. hermonthica counts and stemborer damage …

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Influence Of Optical Cues From Conspecific Females On Escalation Decisions During Male-Male Interactions Of Jumping Spiders, Fiona R. Cross, Robert R. Jackson, Simon D. Pollard, Mark W. Walker Sep 2006

Influence Of Optical Cues From Conspecific Females On Escalation Decisions During Male-Male Interactions Of Jumping Spiders, Fiona R. Cross, Robert R. Jackson, Simon D. Pollard, Mark W. Walker

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An important prediction from game theory is that the value of a resource influences the level to which male-male conflict escalates. An earlier experimental study showed that males of Hypoblemum albovittatum, a common salticid in New Zealand, can discern by sight alone whether a female is in the vicinity and that, having detected a female's presence, males escalate (i.e., adopt behaviour that is likely to put them at greater risk of injury). Seeing a bare moving cork, a conspecific male or a prey item also elicits escalation, but not to the level elicited by seeing a conspecific female. Here the …

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Biological Impact Of The Exotic Parasitoid, Diadegma Semiclausum (Hellen), Of Diamondback Moth, Plutella Xylostella L., In Kenya, Caleb Momanyi, Bernhard Löhr, Linus Gitonga Aug 2006

Biological Impact Of The Exotic Parasitoid, Diadegma Semiclausum (Hellen), Of Diamondback Moth, Plutella Xylostella L., In Kenya, Caleb Momanyi, Bernhard Löhr, Linus Gitonga

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Diadegma semiclausum (Hellen) was introduced to Kenya from Taiwan for the control of diamondback moth (DBM), Plutella xylostella L., and released for the first time in July 2002. Seven and twelve months after release, field mortality studies using the cage exclusion method were conducted at two release sites (Werugha/Taita Hills and Tharuni/Central Kenya). Four treatments were applied: fully closed and partially open cages, both with and without glue applied to the base of the plants for the exclusion of crawling predators. During this time interval, parasitism of exposed larvae rose from 15 to 60% at Werugha and from 8 to …

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Population Models For Threshold-Based Control Of Tetranychus Urticae In Small-Scale Kenyan Tomato Fields And For Evaluating Weather And Host Plant Species Effects, Markus Knapp, Ibrahima Sarr, Gianni Gilioli, Johann Baumgärtner Aug 2006

Population Models For Threshold-Based Control Of Tetranychus Urticae In Small-Scale Kenyan Tomato Fields And For Evaluating Weather And Host Plant Species Effects, Markus Knapp, Ibrahima Sarr, Gianni Gilioli, Johann Baumgärtner

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The spatial distribution of motile life stages of the two-spotted spider mite Tetranychus urticae Koch in Kenyan small-scale tomato fields was described by Taylor's power law and an enumerative sampling plan was designed for research purposes. The exponential increase of T. urticae populations during three growing seasons permits the development and use of a simple exponential model for the design of a threshold-based chemical control system. For this purpose, a critical threshold of 440 motile mites per sample unit at the end of the growing season (12 weeks after transplanting) was translated into a proportion of 0.83 infested units in …

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Suitability Of Cultivated And Wild Crucifers For The Development Of Diamondback Moth, Plutella Xylostella L. (Lepidoptera: Plutellidae), G. Ayalew, B. Löhr, C. K.P.O. Ogol, J. Baumgärtner Jul 2006

Suitability Of Cultivated And Wild Crucifers For The Development Of Diamondback Moth, Plutella Xylostella L. (Lepidoptera: Plutellidae), G. Ayalew, B. Löhr, C. K.P.O. Ogol, J. Baumgärtner

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The performance of the Diamondback moth, Plutella xylostella L., on Ethiopian cultivated and wild crucifers was studied in the laboratory for two generations. Head cabbage, Brassica oleracea var. capitata L., was the most suitable host with the shortest developmental period and the highest reproductive potential. Both developmental period and life table statistics showed that the weed Erucastrum arabicum Fisch. and Mey was more suitable than some of the cultivated species. © 2006 Academic Journals Inc.

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Does A Specialist Parasitoid Adapt To Its Host On A New Host Plant?, A. Roßbach, B. Löhr, S. Vidal Jul 2006

Does A Specialist Parasitoid Adapt To Its Host On A New Host Plant?, A. Roßbach, B. Löhr, S. Vidal

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The host plant expansion of a diamondback moth, Plutella xylostella (L.) (DBM) strain to snowpea (Pisum sativum L.) raised the question whether a specialist parasitoid Diadegma semiclausum (DS) could be conditioned to locate and parasitize its host on the new host plant. In a specialist parasitoid a behavioural change towards a plant outside the normal host plant range of its host due to developmental experience is not expected. The responsive behaviour, parasitism rates and fitness of three subsequent DS generations were investigated on the snowpea-strain of DBM. After three generations of DS on the pea 62.5% of females chose an …

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Effect Of Jatropha Gossypiifolia Leaf Extracts On Three Lepidoptera Species, J. Arnubio Valencia, Brigitte Frérot, Herve Guénego, Diego F. Múnera, Maria Fátima De Sá Grossi, Paul André Calatayud Jun 2006

Effect Of Jatropha Gossypiifolia Leaf Extracts On Three Lepidoptera Species, J. Arnubio Valencia, Brigitte Frérot, Herve Guénego, Diego F. Múnera, Maria Fátima De Sá Grossi, Paul André Calatayud

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Leaf extracts of Jatropha gossypiifolia L. (Euphorbiaceae) contain compounds that are toxic to insects. In this study, these extracts were tested against larvae of three lepidopteran species, Busseola fusca (Fuller) (Lepidoptera: Noctuidae), Ostrinia nubilalis Hubner (Lepidoptera: Pyralidae) and Sesamia nonagrioides Lef. (Lepidoptera: Noctuidae), which are important pests of maize in Africa, Europe and Mediterranean countries, respectively. Leaf extracts were shown to be highly toxic to neonate larvae of B. fusca and O. nubilalis quickly after they were ingested. In contrast, no effect was found on fourth instar O. nubilalis and a low level of toxicity was observed on neonates of …

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The Effect Of Temperature And Humidity On The Bionomics Of Six African Egg Parasitoids (Hymenoptera: Trichogrammatidae), A. Kalyebi, W. A. Overholt, F. Schulthess, J. M. Mueke, S. Sithanantham Jun 2006

The Effect Of Temperature And Humidity On The Bionomics Of Six African Egg Parasitoids (Hymenoptera: Trichogrammatidae), A. Kalyebi, W. A. Overholt, F. Schulthess, J. M. Mueke, S. Sithanantham

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The life table statistics of six native Kenyan species/strains of Trichogramma and Trichogrammatoidea were established using a factitious host Corcyra cephalonica, Stainton (Lepidoptera: Pyralidae), at eight different temperatures (10, 15, 20, 25, 28, 30, 32 and 35°C) and two humidity levels (40-50 and 70-80%). The objective was to select insects with superior attributes for augmentative release against lepidopteran pests in horticultural crops. Both temperature and humidity affected developmental time and life table parameters of the parasitoids but temperature played a more critical role. Developmental time was inversely related to temperature. The intrinsic and finite rates of increase increased with temperature …

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Contribution Of Natural Food Sources To Reproductive Behaviour, Fecundity And Longevity Of Ceratitis Cosyra, C. Fasciventris And C. Capitata (Diptera: Tephritidae), A. Manrakhan, S. A. Lux Jun 2006

Contribution Of Natural Food Sources To Reproductive Behaviour, Fecundity And Longevity Of Ceratitis Cosyra, C. Fasciventris And C. Capitata (Diptera: Tephritidae), A. Manrakhan, S. A. Lux

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The influence of food sources comprising the natural diet on the reproductive behaviour, fecundity and longevity of three African fruit flies Ceratitis cosyra (Walker), C. fasciventris (Bezzi) and C. capitata (Wiedemann) was investigated. Three natural food sources, varying in protein and sugar content, were evaluated. These included bird droppings (farm chicken), aphid honeydew and guava (Psidium guajava L.) juice. For C. fasciventris and C. capitata, flies fed on a protein-rich diet displayed higher frequency of calling, mating and oviposition than flies fed on a protein-poor diet, whilst for C. cosyra, quality of diet significantly influenced the mating behaviour of the …

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Spatially Targeting Culex Quinquefasciatus Aquatic Habitats On Modified Land Cover For Implementing An Integrated Vector Management (Ivm) Program In Three Villages Within The Mwea Rice Scheme, Kenya, Benjamin G. Jacob, Josephat Shililu, Ephantus J. Muturi, Joseph M. Mwangangi, Simon M. Muriu, Jose Funes, John Githure, James L. Regens, Robert J. Novak May 2006

Spatially Targeting Culex Quinquefasciatus Aquatic Habitats On Modified Land Cover For Implementing An Integrated Vector Management (Ivm) Program In Three Villages Within The Mwea Rice Scheme, Kenya, Benjamin G. Jacob, Josephat Shililu, Ephantus J. Muturi, Joseph M. Mwangangi, Simon M. Muriu, Jose Funes, John Githure, James L. Regens, Robert J. Novak

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Background: Continuous land cover modification is an important part of spatial epidemiology because it can help identify environmental factors and Culex mosquitoes associated with arbovirus transmission and thus guide control intervention. The aim of this study was to determine whether remotely sensed data could be used to identify rice-related Culex quinquefasciatus breeding habitats in three rice-villages within the Mwea Rice Scheme, Kenya. We examined whether a land use land cover (LULC) classification based on two scenes, IKONOS at 4 m and Landsat Thematic Mapper at 30 m could be used to map different land uses and rice planted at different …

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Phylogenetic Study Of Diadegma Species (Hymenoptera: Ichneumonidae) Inferred From Analysis Of Mitochondrial And Nuclear Dna Sequences, Barbara Wagener, Annette Reineke, Bernhard Löhr, Claus P.W. Zebitz May 2006

Phylogenetic Study Of Diadegma Species (Hymenoptera: Ichneumonidae) Inferred From Analysis Of Mitochondrial And Nuclear Dna Sequences, Barbara Wagener, Annette Reineke, Bernhard Löhr, Claus P.W. Zebitz

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The genus Diadegma consists of a large group of parasitoid wasps with a confusing taxonomy based on morphological characters. No phylogenetic studies on this genus or any of its species have been published so far. We examined DNA variations in a 498 bp segment of the cytochrome oxidase I gene (COI) of mitochondrial DNA (mtDNA) and in the internal transcribed spacer 2 (ITS2) of ribosomal DNA (rDNA) and compared nine different Diadegma species (i.e., D. semiclausum, D. insulare, D. fenestrale, D. mollipla, D. rapi., D. leontiniae, D. chrysostictos, D. armillata, D. blackburni) from various geographical origins. Interspecific variation ranged from …

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Mate Location Mechanism And Phase-Related Mate Preferences In Solitarius Desert Locust, Schistocerca Gregaria, Sidi Ould Ely, Hassan Mahamat, Peter G.N. Njagi, Magzoub Omer Bashir, Salah El-Tom El-Amin, Ahmed Hassanali May 2006

Mate Location Mechanism And Phase-Related Mate Preferences In Solitarius Desert Locust, Schistocerca Gregaria, Sidi Ould Ely, Hassan Mahamat, Peter G.N. Njagi, Magzoub Omer Bashir, Salah El-Tom El-Amin, Ahmed Hassanali

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Mate location responses of male and female solitary-reared locusts that had either experienced no crowding or that had been crowded for varying periods were studied in a flatbed wind tunnel. Two hypotheses were explored: that both sexes of this phase of the locust participate in locating the other by using a combination of chemical and visual signals, and that individuals that experience some crowding (i.e., undergo varying levels of phase shift) can compete effectively with their solitary counterparts in mate location and mating. Our results confirm that both male and female solitarious locusts actively participate in mate location, although the …

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Diel Periodicity In The Production Of Green Leaf Volatiles By Wild And Cultivated Host Plants Of Stemborer Moths, Chilo Partellus And Busseola Fusca, K. Chamberlain, Z. R. Khan, J. A. Pickett, T. Toshova, L. J. Wadhams Mar 2006

Diel Periodicity In The Production Of Green Leaf Volatiles By Wild And Cultivated Host Plants Of Stemborer Moths, Chilo Partellus And Busseola Fusca, K. Chamberlain, Z. R. Khan, J. A. Pickett, T. Toshova, L. J. Wadhams

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The volatile chemicals produced by four poaceous plant species, blue thatching grass, Hyparrhenia tamba, Napier grass, Pennisetum purpureum, sorghum, Sorghum bicolor, and maize, Zea mays, which are host plants for the lepidopterous stemborers, Chilo partellus and Busseola fusca, were collected by air entrainment and analyzed by gas chromatography. The total quantities of volatiles collected hourly, over a 9-hr period, from P. purpureum and H. tamba showed an approximately hundredfold increase in the first hour of the scotophase. Thereafter, the amount decreased rapidly to levels present during photophase. Although onset of scotophase also triggered an increase in quantities of volatiles collected …

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Reproductive Isolation And Differentiation Between Five Populations Of Cotesia Plutellae (Hymenoptera: Braconidae), Parasitoid Of Plutella Xylostella (Lepidoptera: Plutellidae), Claudia Rincon, Dominique Bordat, Bernhard Löhr, Stéphane Dupas Feb 2006

Reproductive Isolation And Differentiation Between Five Populations Of Cotesia Plutellae (Hymenoptera: Braconidae), Parasitoid Of Plutella Xylostella (Lepidoptera: Plutellidae), Claudia Rincon, Dominique Bordat, Bernhard Löhr, Stéphane Dupas

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Many taxa used in biological control may be composed of several population units reproductively isolated to various degrees. Yet, the introductions of non-compatible populations may result in a depression of intended biological control. Cotesia plutellae has been widely used as a biological control agent of the diamondback moth, Plutella xylostella. However, not all introductions and augmentations were successful. With the aim to develop markers of compatibility for this species, we studied the reproductive compatibility between five populations (South Africa, Benin, Martinique, Reunion, and Taiwan) and analyzed its statistical relationship with three morphological characters (antennae and body length and antennae/body ratio), …

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Interspecific Competition Between Xanthopimpla Stemmator Thunberg And Dentichasmias Busseolae Heinrich (Hymenoptera: Ichneumonidae), Pupal Parasitoids Attacking Chilo Partellus (Lepidoptera: Crambidae) In East Africa, Benjamin K. Muli, Fritz Schulthess, Rosebella O. Maranga, Helen L. Kutima, Nanqing Jiang Feb 2006

Interspecific Competition Between Xanthopimpla Stemmator Thunberg And Dentichasmias Busseolae Heinrich (Hymenoptera: Ichneumonidae), Pupal Parasitoids Attacking Chilo Partellus (Lepidoptera: Crambidae) In East Africa, Benjamin K. Muli, Fritz Schulthess, Rosebella O. Maranga, Helen L. Kutima, Nanqing Jiang

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Interspecific competition between Xanthopimpla stemmator and Dentichasmias busseolae was studied using pupae of the invasive crambid stemborer Chilo partellus as the host. While X. stemmator is an old association, D. busseolae formed a relatively new association with C. partellus in East Africa. Two different time intervals between parasitism (0 and 48 h) and two parasitoid sequences [i.e., X. stemmator before D. busseolae (Xs-Db) and D. busseolae before X. stemmator (Db-Xs)] were chosen. In addition, the parasitoids' performance on pupae in maize stems and ears was assessed. For both X. stemmator and D. busseolae, there was no difference in foraging time …

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Oviposition Behavior Of Female Anopheles Gambiae In Eestern Kenya Inferred From Microsatellite Markers, Hong Chen, Ulrike Fillinger, Guiyun Yan Jan 2006

Oviposition Behavior Of Female Anopheles Gambiae In Eestern Kenya Inferred From Microsatellite Markers, Hong Chen, Ulrike Fillinger, Guiyun Yan

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Anopheles gambiae females in a relatively isolated hut and all larvae from larval habitats within 100 m of the hut were collected in August 2001 in western Kenya. Among 42 aquatic habitats, 16 had A. gambiae larvae. Two hundred fifty larvae and 58 adults were genotyped using nine microsatellite markers to infer sibling relationship between the larvae and maternity between the females and larvae. The pairwise genetic relatedness of A. gambiae larvae per habitat ranged from -0.4112 to 0.9375, indicating that full siblings, half siblings, and genetically unrelated individuals presented at those habitats with multiple larvae. From a likelihood analysis, …

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Molecular Characterization Of A Tsetse Fly Midgut Proteolytic Lectin That Mediates Differentiation Of African Trypanosomes, Laila U. Abubakar, Wallace D. Bulimo, Francis J. Mulaa, Ellie O. Osir Jan 2006

Molecular Characterization Of A Tsetse Fly Midgut Proteolytic Lectin That Mediates Differentiation Of African Trypanosomes, Laila U. Abubakar, Wallace D. Bulimo, Francis J. Mulaa, Ellie O. Osir

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Differentiation of bloodstream-form trypanosomes into procyclic (midgut) forms is an important first step in the establishment of an infection within the tsetse fly. This complex process is mediated by a wide variety of factors, including those associated with the vector itself, the trypanosomes and the bloodmeal. As part of an on-going project in our laboratory, we recently isolated and characterized a bloodmeal-induced molecule with both lectin and trypsin activities from midguts of the tsetse fly, Glossina longipennis [Osir, E.O., Abubakar, L., Imbuga, M.O., 1995. Purification and characterization of a midgut lectin-trypsin complex from the tsetse fly, Glossina longipennis. Parasitol. Res. …

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New Bioassay Method To Assess The Pathogenicity Of Colombian Strains Of Metarhizium Anisopliae (Metsch.) Sorokin And Paecilomyces Sp. (Deuteromycotina: Hyphomycetes) Against The Subterranean Burrower Bug Cyrtomenus Bergi Froeschner (Hemiptera: Cydnidae), Juliana Jaramillo, Christian Borgemeister Jan 2006

New Bioassay Method To Assess The Pathogenicity Of Colombian Strains Of Metarhizium Anisopliae (Metsch.) Sorokin And Paecilomyces Sp. (Deuteromycotina: Hyphomycetes) Against The Subterranean Burrower Bug Cyrtomenus Bergi Froeschner (Hemiptera: Cydnidae), Juliana Jaramillo, Christian Borgemeister

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Using a new sand bioassay method, the pathogenicity of three Colombian strains of Metarhizium anisopliae (i.e., CIAT 224, 245, and 230) and one strain of Paecilomyces sp. (CIAT 308) were tested against fourth instars of the subterranean burrower bug Cyrtomenus bergi Froeschner (Hem.: Cydnidae) in the laboratory. The proposed bioassay simulates the habitat of C. bergi and at the same time enables the evaluation of a large number of insects in a short period of time and under controlled conditions. All tested fungal species/strains were pathogenic against C. bergi. However, only low levels of mortality were obtained, and never exceeded …

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Incidence Of Larval And Pupal Parasitoids Of Lepidoptera In Uganda With Special Reference To New Associations, I. Rwomushana, S. Kyamanywa, A. J. Ngi-Song, C. O. Omwega Dec 2005

Incidence Of Larval And Pupal Parasitoids Of Lepidoptera In Uganda With Special Reference To New Associations, I. Rwomushana, S. Kyamanywa, A. J. Ngi-Song, C. O. Omwega

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Cotesia flavipes Cameron (Hymenoptera: Braconidae) was introduced in Uganda in 1998 for the biological control of the old association cereal stemborer Chilo partellus (Swinhoe) (Lepidoptera: Crambidae). However there is little information on whether this parasitoid will attack new association Lepidoptera, which in turn may have implications on its efficacy on Ch. partellus. This study investigated the incidence of introduced Co. flavipes on Ch. partellus, and new association lepidopteran species and associated effects on its efficacy. Parasitism levels for Co. flavipes in several locations varied between 13.7-34.8% and 1.5-18.8% on Ch. partellus and new association hosts, respectively. Implications for biological control …

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Variations In Races Of The Honeybee Apis Mellifera (Hymenoptera: Apidae) In Kenya, S. K. Raina, D. M. Kimbu Dec 2005

Variations In Races Of The Honeybee Apis Mellifera (Hymenoptera: Apidae) In Kenya, S. K. Raina, D. M. Kimbu

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The three races of the honeybee Apis mellifera Linnaeus in Kenya (A. m. scutellata, A. m. monticola and A. m. litorea) differ from each other with respect to size, cubital index and abdominal colour banding pattern. These differences were used to assess the extent of interbreeding and hybridization between the races. This was verified on the basis of selected morphometric traits. Bee samples were collected from traditional log hives in seven geographical locations throughout Kenya ranging from lowland Mombasa in the coastal region to the highland Kinangop ranges. The length and width of the right forewing, length of proboscis, right …

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The Effect Of Nitrogen Fertilizer Application To Maize And Sorghum On The Bionomics Of Chilo Partellus (Lepidoptera: Crambidae) And The Performance Of Its Larval Parasitoid Cotesia Flavipes (Hymenoptera: Braconidae), N. Jiang, F. Schulthess Dec 2005

The Effect Of Nitrogen Fertilizer Application To Maize And Sorghum On The Bionomics Of Chilo Partellus (Lepidoptera: Crambidae) And The Performance Of Its Larval Parasitoid Cotesia Flavipes (Hymenoptera: Braconidae), N. Jiang, F. Schulthess

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Laboratory and field trials were conducted to evaluate the effect of plant species (maize, sorghum), plant age (young, middle, old) and four different nitrogen fertilization levels (N0-N3) on the bionomics of the invasive crambid Chilo partellus and the performance of its braconid larval parasitoid Cotesia flavipes. Plant N varied significantly between N0 and N1-N3, but the differences among the latter were not significant. Intrinsic rates of increase and net-reproductive rates of C. partellus followed the same trends: they were lowest with N0 and similar among the other treatments. On maize only, mortality of C. partellus and parasitism by C. flavipes …

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Relationships Of Intercropped Maize, Stem Borer Damage To Maize Yield And Land-Use Efficiency In The Humid Forest Of Cameroon, A. Chabi-Olaye, C. Nolte, F. Schulthess, C. Borgemeister Oct 2005

Relationships Of Intercropped Maize, Stem Borer Damage To Maize Yield And Land-Use Efficiency In The Humid Forest Of Cameroon, A. Chabi-Olaye, C. Nolte, F. Schulthess, C. Borgemeister

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Stem borers are the most important maize pests in the humid forest zone of Cameroon. Field trials were conducted in the long and short rainy seasons of 2002 and 2003 to assess the level of damage and yield reductions caused by stem borers in monocropped maize and in maize intercropped with non-host plants such as cassava, cowpea and soybean. The intercrops were planted in two spatial arrangements, i.e. alternating hills or alternating rows. All intercrops and the maize monocrop were grown with and without insecticide treatment for assessment of maize yield loss due to borer attacks. The land-use efficiency of …

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Fitness Consequences Of Anopheles Gambiae Population Hybridization, David M. Menge, Tom Guda, Daibin Zhong, Aditi Pai, Goufa Zhou, John C. Beier, Louis Gouagna, Guiyun Yan Sep 2005

Fitness Consequences Of Anopheles Gambiae Population Hybridization, David M. Menge, Tom Guda, Daibin Zhong, Aditi Pai, Goufa Zhou, John C. Beier, Louis Gouagna, Guiyun Yan

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Background: The use of transgenic mosquitoes with parasite inhibiting genes has been proposed as an integral strategy to control malaria transmission. However, release of exotic transgenic mosquitoes will bring in novel alleles along with parasite-inhibiting genes that may have unknown effects on native populations. Thus it is necessary to study the effects and dynamics of fitness traits in native mosquito populations in response to the introduction of novel genes. This study was designed to evaluate the dynamics of fitness traits in a simulation of introduction of novel alleles under laboratory conditions using two strains of Anopheles gambiae: Mbita strain from …

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Termite (Isoptera) Diversity In Senegal And Their Damage On Reforestation Areas And Cultures, Makhfousse Sarr, Nguya K. Maniania, A. Russell-Smith, Abdoulaye Niassy Sep 2005

Termite (Isoptera) Diversity In Senegal And Their Damage On Reforestation Areas And Cultures, Makhfousse Sarr, Nguya K. Maniania, A. Russell-Smith, Abdoulaye Niassy

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Studies conducted from 1969 to 2000 on termite ecology and biology in Senegal revealed high termite diversity and an influence of climate and soil conditions on termite group distribution. Sixty-four termite species were recorded. Some were specific to ecologically similar zones while others were widely distributed. Some species, known to inhabit wet zones, were found in semi-arid zones where relic forest vegetation still exists. Nioro, in the central part of the country, seems to be the buffer zone between species to the north and south of Senegal. In Ferlo, an arid zone, Macrotermes species was in regression and the subsisting …

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The Effect Of Host Larvae On Three Psyttalia Species (Hymenoptera: Braconidae), Parasitoids Of Fruit-Infesting Flies (Diptera: Tephritidae), M. K. Billah, S. Kimani-Njogu, W. A. Overholt, R. A. Wharton, D. D. Wilson, M. A. Cobblah Sep 2005

The Effect Of Host Larvae On Three Psyttalia Species (Hymenoptera: Braconidae), Parasitoids Of Fruit-Infesting Flies (Diptera: Tephritidae), M. K. Billah, S. Kimani-Njogu, W. A. Overholt, R. A. Wharton, D. D. Wilson, M. A. Cobblah

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Three species of fruit fly parasitoids, Psyttalia concolor (Szépligeti), Psyttalia cosyrae (Wilkinson) and Psyttalia lounsburyi (Silvestri) (Hymenoptera: Braconidae) were reared on different host larvae to determine the effects of host species, size and colour on parasitoid development. Ovipositor, ovipositor sheath and hind tibia lengths were found to be different for progenies from preferred and non-preferred host larvae. Ratios of ovipositor-tibia and ovipositor sheath-tibia showed no difference when P. concolor was reared on a bigger host (Ceratitis cosyra (Walker) (Diptera: Tephritidae), whereas rearing P. cosyrae on a smaller host (C. capitata (Wiedemann) showed significant differences. Comparison of the linear measurements, ratios …

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Repellency Of Essential Oils Of Some Plants From The Kenyan Coast Against Anopheles Gambiae, Josiah O. Odalo, Maurice O. Omolo, Hamisi Malebo, John Angira, Patrick M. Njeru, Isaiah O. Ndiege, Ahmed Hassanali Sep 2005

Repellency Of Essential Oils Of Some Plants From The Kenyan Coast Against Anopheles Gambiae, Josiah O. Odalo, Maurice O. Omolo, Hamisi Malebo, John Angira, Patrick M. Njeru, Isaiah O. Ndiege, Ahmed Hassanali

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Volatile oils extracted by hydrodistillation from six plant species growing in the Kenyan coast, Croton pseudopulchellus Pax, Mkilua fragrans Verdc. (Annonaceae), Endostemon tereticaulis (poir.) Ashby, Ocimum forskolei Benth., Ocimum fischeri Guerke and Plectranthus longipes Baker (Labiateae), were evaluated for repellency on forearms of human volunteers against Anopheles gambiae sensu stricto. All oils were found to be more repellent (RC50 range = 0.67-9.21 × 10-5 mg cm-2) than DEET (RC50 = 33 × 10-5 mg cm-2). The individual components of the oils were identified by GC-MS and GC co-injections with authentic standards. The repellency of 15 of the main constituents of …

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Generalism Versus Specialism: Responses Of Diadegma Mollipla (Holmgren) And Diadegma Semiclausum (Hellen), To The Host Shift Of The Diamondback Moth (Plutella Xylostella L.) To Peas, A. Roßbach, B. Löhr, S. Vidal Jul 2005

Generalism Versus Specialism: Responses Of Diadegma Mollipla (Holmgren) And Diadegma Semiclausum (Hellen), To The Host Shift Of The Diamondback Moth (Plutella Xylostella L.) To Peas, A. Roßbach, B. Löhr, S. Vidal

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A population of the diamondback moth Plutella xylostella (L.) (Lepidoptera: Plutellidae) (DBM) was recently found to infest sugar snap- and snowpeas in the Rift Valley in Kenya, causing heavy damage. The influence of this host shift on host location preferences of two parasitoids was investigated: The indigenous Diadegma mollipla (Holmgren) regarded as a relative generalist, and Diadegma semiclausum(Hellen), regarded as highly specific to DBM. The attractiveness of different odour sources was compared for the two parasitoid species using a Y-tube olfactometer using naïve females. D. mollipla was not significantly attracted to any cabbage related odours but showed a significant preference …

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Time And Frequency Of Applications Of Entomopathogenic Nematodes And Their Persistence For Control Of Western Flower Thrips Frankliniella Occidentalis, Difabachew Belay, Lemma Ebssa, Christian Borgemeister Jul 2005

Time And Frequency Of Applications Of Entomopathogenic Nematodes And Their Persistence For Control Of Western Flower Thrips Frankliniella Occidentalis, Difabachew Belay, Lemma Ebssa, Christian Borgemeister

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Post application persistence of two entomopathogenic nematode (EPN) species, Heterorhabditis bacteriophora strain HK3 and Steinernema carpocapsae strain DD136, was studied against soil-dwelling late second instar larvae (L2) of western flower thrips (WFT) Frankliniella occidentalis (Thysanoptera: Thripidae). The nematodes were applied at 200 and 400 infective juveniles (IJ) cm-2, and L2 WFT were introduced at 0 (same day), 3, 6, 9 or 12 days after nematode application (DANA). Heterorhabditis bacteriophora caused higher thrips mortality than S. carpocapsae in most of the tests and both species persisted for at least 6 days, causing WFT mortality of up to 76 and 37.8%, respectively. …

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Effects Of Grain Legumes And Cover Crops On Maize Yield And Plant Damage By Busseola Fusca (Fuller) (Lepidoptera: Noctuidae) In The Humid Forest Of Southern Cameroon, A. Chabi-Olaye, C. Nolte, F. Schulthess, C. Borgemeister Jun 2005

Effects Of Grain Legumes And Cover Crops On Maize Yield And Plant Damage By Busseola Fusca (Fuller) (Lepidoptera: Noctuidae) In The Humid Forest Of Southern Cameroon, A. Chabi-Olaye, C. Nolte, F. Schulthess, C. Borgemeister

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Field trials were run in the humid forest zone of Cameroon to investigate the effects of crop rotation, cover crops and bush fallow on infestations by the noctuid stemborer Busseola fusca (Fuller) and on yield of maize. A continuous maize production system was compared with crop sequence systems, in which maize followed a grain legume (cowpea, soybean), cover crop (mucuna, pigeon pea) or a bush fallow. Compared to the continuous maize cropping system, maize in the crop sequence with legume and fallow systems had significantly higher leaf and stem nitrogen content at 35 and 63 days after planting (DAP), respectively. …

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Life Tables, Key Factor Analysis And Density Relations Of Natural Populations Of The Spotted Maize Stemborer, Chilo Partellus (Lepidoptera: Crambidae), Under Different Cropping Systems At The Kenyan Coast, C. A.O. Midega, C. K.P.O. Ogol, W. A. Overholt Jun 2005

Life Tables, Key Factor Analysis And Density Relations Of Natural Populations Of The Spotted Maize Stemborer, Chilo Partellus (Lepidoptera: Crambidae), Under Different Cropping Systems At The Kenyan Coast, C. A.O. Midega, C. K.P.O. Ogol, W. A. Overholt

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Studies were conducted at Mtwapa, in the coastal area of Kenya, during the long and short rains of 1999 and 2000 to evaluate interaction of mortality factors in lowering Chilo partellus (Swinhoe) populations in diverse agroecosystems. Treatments consisted of hedgerows of leucaena only, gliricidia only, alternating rows of leucaena and gliricidia, and three plots without trees. During the cropping seasons, maize was planted between the hedgerows while a row of cowpea was planted between the rows of maize. One of the plots without trees was planted to an intercrop of maize and cowpea. The remaining two plots without trees were …

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