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Articles 2191 - 2220 of 2421

Full-Text Articles in Life Sciences

Effect Of Temperature On The Development Of Orius Albidipennis Reuter, A Predator Of The African Legume Flower Thrips, Megalurothrips Sjostedti Trybom, L. M. Gitonga, B. Löhr, W. A. Overholt, J. K. Magambo, J. M. Mueke Jan 2002

Effect Of Temperature On The Development Of Orius Albidipennis Reuter, A Predator Of The African Legume Flower Thrips, Megalurothrips Sjostedti Trybom, L. M. Gitonga, B. Löhr, W. A. Overholt, J. K. Magambo, J. M. Mueke

All Peer-Reviewed Publications

The effects of temperature on the development of Orius albidipennis (Reuter) (Hemiptera: Anthocoridae), reared on its prey, Megalurothrips sjostedti (Trybom) (Thysanoptera: Thripidae), were studied in the laboratory. Nymphal mortality was 87, 48 and 38% at 20, 25 and 30 °C, respectively. With the exception of first-instar nymphs, percentage mortality was lowest at 25 °C. Pre-oviposition period and longevity decreased with an increase in temperature. Mean daily and total fecundity were 2.1 and 76.4 respectively at 25 °C. The mean developmental period from oviposition to adult eclosion was 27.7, 14.1 and 10.9 days at 20, 25 and 30 °C respectively. There …

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Comparative Development And Population Growth Of An Exotic Stemborer, Chilo Partellus (Swinhoe), And An Ecologically Similar Congener, C. Orichalcociliellus (Strand) (Lepidoptera: Crambidae), Jacob C. Mbapila, William A. Overholt, Hosea Y. Kayumbo Jan 2002

Comparative Development And Population Growth Of An Exotic Stemborer, Chilo Partellus (Swinhoe), And An Ecologically Similar Congener, C. Orichalcociliellus (Strand) (Lepidoptera: Crambidae), Jacob C. Mbapila, William A. Overholt, Hosea Y. Kayumbo

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Studies were conducted to determine the effect of temperature and diet on the development of Chilo partellus (Swinhoe) and Chilo orichalcociliellus (Strand) (Lepidoptera: Crambidae). Developmental times of C. partellus and C. orichalcociliellus for the egg, larval and egg-adult life stages were inversely related to temperature. The larval developmental period of C. orichalcociliellus reared on artificial diet was longer than the developmental period on natural diet. Chilo partellus had a higher intrinsic rate of natural increase than C. orichalcociliellus at all diet/temperature combinations except natural diet at 31°C. © 2002 ICIPE.

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Predicting The Distribution Of Chilo Partellus (Swinhoe) And Its Parasitoid Cotesia Flavipes Cameron In Ethiopia Using Correlation, Step-Wise Regression And Geographic Information Systems, G. Emana, W. A. Overholt, E. Kairu, L. Macopiyo, G. Zhou Jan 2002

Predicting The Distribution Of Chilo Partellus (Swinhoe) And Its Parasitoid Cotesia Flavipes Cameron In Ethiopia Using Correlation, Step-Wise Regression And Geographic Information Systems, G. Emana, W. A. Overholt, E. Kairu, L. Macopiyo, G. Zhou

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The recent development of geographic information systems (GIS) provides new avenues for analysing spatial patterns in insect populations. Field survey data, along with GIS and statistical models were used to predict the distribution of Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) and Cotesia flavipes Cameron (Hymenoptera: Braconidae) in Ethiopia. The results obtained suggested that the distributions of Ch. parlellus and Co. flavipes were affected by rainfall and temperature. The predicted distributions of Ch. parlellus and Co. flavipes were similar. Validation of predicted values is discussed. © 2002 ICIPE.

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Comparative Life Table Statistics Of Exochomus Flaviventris Reared On The Cassava Mealybug, Phenacoccus Manihoti, Fed On Four Host Plants, B. P. Le Rü, A. Mitsipa Jan 2002

Comparative Life Table Statistics Of Exochomus Flaviventris Reared On The Cassava Mealybug, Phenacoccus Manihoti, Fed On Four Host Plants, B. P. Le Rü, A. Mitsipa

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The demographic statistics of the ladybird Exochomus flaviventris Mader (Coleoptera: Coccinellidae) were investigated under laboratory conditions on the cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Homoptera: Pseudococcidae), reared on four host plants with different levels of antibiotic resistance to the mealybug: two cassava (Manihot esculenta Crantz, Euphorbiaceae) varieties, Incoza and Zanaga, Faux-Caoutchouc (FC) (hybrid of M. esculenta x M. glaziovii Muel. Arg.) and water weed (Talinum triangulare Jack, Portulacacae). Preimaginal mortality, mean oviposition time and total fecundity of female ladybirds were strongly affected by the host plant even though there was no linkage with antibiotic resistance. The net reproduction rates R o …

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Evidence Of Adaptation Of Diamondback Moth, Plutella Xylostella (L.), To Pea, Pisum Sativum L., Bernhard Löhr, Ruth Gathu Jan 2002

Evidence Of Adaptation Of Diamondback Moth, Plutella Xylostella (L.), To Pea, Pisum Sativum L., Bernhard Löhr, Ruth Gathu

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A strain of diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), adapted to peas was detected in 1999 in the export vegetable growing area south of Lake Naivasha in the Rift Valley Province of Kenya. The pea strain (DBM-P) was compared in laboratory studies to the normal crucifer strain (DBM-C). Whereas DBM-P performed comparably well on kales and peas, the cabbage strain (DBM-C) suffered heavy mortality on peas. Out of the 250 DBM-C first instars, only six reached adult stage on pea. In addition, larval development was prolonged by five days on peas as compared to kale, and larval growth …

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Description Of The First-Instar Larva Of Geocharidius (Coleoptera: Carabidae: Trechitae) With A Discussion Of The Phylogeny Of The Subtribe Anillina, Vasily V. Grebennikov Jan 2002

Description Of The First-Instar Larva Of Geocharidius (Coleoptera: Carabidae: Trechitae) With A Discussion Of The Phylogeny Of The Subtribe Anillina, Vasily V. Grebennikov

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This paper describes the first-instar larva of Geocharidius Jeannel, a species from Mexico, which is the second record of an Anillina (Coleoptera: Carabidae: Trechitae) larva; previously described was a species of the European genus Typhlocharis. Larvae of these two genera share ten synapomorphic characters, which support the monophyletic origin of Anillina. Sister-group relationships of Anillina with Tachyina + Xystosomina are proposed on the basis of three shared larval synapomorphies: seta LA5 of ligula absent; coronal suture in first-instar larvae very short or absent; second- third-instar larvae have none or one secondary seta on lateral sides of stipes and labium and …

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Laboratory Evaluation Of The Entomopathogenic Fungus, Metarhizium Anisopliae For The Control Of The Groundnut Bruchid, Caryedon Serratus On Groundnut, S. Ekesi, E. A. Egwurube, A. D. Akpa, I. Onu Nov 2001

Laboratory Evaluation Of The Entomopathogenic Fungus, Metarhizium Anisopliae For The Control Of The Groundnut Bruchid, Caryedon Serratus On Groundnut, S. Ekesi, E. A. Egwurube, A. D. Akpa, I. Onu

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The pathogenicity of five isolates of Metarhizium anisopliae to adult Caryedon serratus was evaluated in the laboratory. All the isolates tested were virulent to the beetle but pathogenicity varied among the isolates. One isolate, CPD 4 was consistently superior to all other isolates in terms of mortality of the beetle, protection of groundnut pods from damage, reduction in progeny production and repellency to the beetle. At 10 days post-treatment, adult mortality treated with 0.1, 0.5 and 1.0 g of dry conidia equivalent to 3.6 × 108, 1.8 × 109 and 3.6 × 109 conidia of isolate CPD 4 per 50 …

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Effect Of Cooling Rate On Crystallization Behavior Of Milk Fat Fraction/Sunflower Oil Blends, Silvana Martini, M. L. Herrera, R. W. Hartel Nov 2001

Effect Of Cooling Rate On Crystallization Behavior Of Milk Fat Fraction/Sunflower Oil Blends, Silvana Martini, M. L. Herrera, R. W. Hartel

Nutrition, Dietetics, and Food Sciences Faculty Publications

The effect of cooling rate (slow: 0.1°C/min; fast: 5.5°C/min) on the crystallization kinetics of blends of a highmelting milk fat fraction and sunflower oil (SFO) was investigated by pulsed NMR and DSC. For slow cooling rate, the majority of crystallization had already occurred by the time the set crystallization temperature had been reached. For fast cooling rate, crystallization started after the samples reached the selected crystallization temperature, and the solid fat content curves were hyperbolic. DSC scans showed that at slow cooling rates, molecular organization took place as the sample was being cooled to crystallization temperature and there was fractionation …

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Modelling The Trappability Of Tsetse, Glossina Fuscipes Fuscipes, In Relation To Distance From Their Natural Habitats, Adedapo Odulaja, Mohamed M. Mohamed-Ahmed Sep 2001

Modelling The Trappability Of Tsetse, Glossina Fuscipes Fuscipes, In Relation To Distance From Their Natural Habitats, Adedapo Odulaja, Mohamed M. Mohamed-Ahmed

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The log-logistic probability distribution function was employed to model trappability of Glossina fuscipes fuscipes, with respect to distance from the edge of two types of habitat. The parameters of the model were obtained using the nonlinear maximum likelihood approach. Asymptotic standard errors of the maximum likelihood estimates were computed for the parameters, and the X2 goodness-of-fit test used to assess the predicted trap catches. Simulation technique was used to estimate the radius of attraction of the unbaited biconical trap for the fly, taking the efficiency of the trap into consideration. The log-logistic model fitted well to a series of observed …

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Predators Of Mesoplatys Ochroptera In Sesbania Planted-Fallows In Eastern Zambia, G. Sileshi, M. Kenis, C. K.P.O. Ogol, S. Sithanantham Aug 2001

Predators Of Mesoplatys Ochroptera In Sesbania Planted-Fallows In Eastern Zambia, G. Sileshi, M. Kenis, C. K.P.O. Ogol, S. Sithanantham

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Mesoplatys ochroptera Stål (Coleoptera: Chrysomelidae) is a serious pest of the tropical legume sesbania (Sesbania sesban (L.) Merrill) widely used for soil fertility improvement in southern Africa. Surveys were conducted between October 1997 and June 1999 in order to identify the predators of M. ochroptera in sesbania fallows in eastern Zambia. The Heteroptera Afrius yolofa (Guérin-Méneville), Glypsus conspicuus (Westwood), Macrorhaphis acuta Dallas, Mecosoma mensor (Germar), Rhinocoris segmentarius (Germar), and Deraeocoris ostentans (Stål), the carabid beetle Cyaneodinodes fasciger (Chaudoir), the ants Tetramorium sericeiventre Emery and Pheidole sp., and the lacewing Mallada sp. were recorded as predators of M. ochroptera for the …

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The Nature Of The Gregarizing Signal Responsible For Maternal Transfer Of Phase To The Offspring In The Desert Locust Schistocerca Gregaria, Atem G. Malual, Ahmed Hassanali, Baldwyn Torto, Yousif O.H. Assad, Peter G.N. Njagi Aug 2001

The Nature Of The Gregarizing Signal Responsible For Maternal Transfer Of Phase To The Offspring In The Desert Locust Schistocerca Gregaria, Atem G. Malual, Ahmed Hassanali, Baldwyn Torto, Yousif O.H. Assad, Peter G.N. Njagi

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We examined aggregative behavior of hatchlings of the desert locust Schistocerca gregaria emerging from solitaria egg pods that had been incubated in sand previously used for consecutive ovipositions by gregarious females. Hatchlings derived from such eggs were significantly more gregarious than those derived from pods laid in clean sand. The gregarizing effect of the sand-associated factor originating from 3, 5, or 10 ovipositions by gregarious females increased in a dose-dependent fashion. Washing the sand with organic solvents following such ovipositions, or flushing it with nitrogen gas, led to substantial loss of its gregarizing effect, showing that the active signal is …

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Effect Of Cooling Rate On Nucleation Behavior Of Milk Fat-Sunflower Oil Blends, Silvana Martini, M. L. Herrera, R. W. Hartel Jun 2001

Effect Of Cooling Rate On Nucleation Behavior Of Milk Fat-Sunflower Oil Blends, Silvana Martini, M. L. Herrera, R. W. Hartel

Nutrition, Dietetics, and Food Sciences Faculty Publications

The effect of cooling rate on the crystallization behavior of mixes of high-melting milk fat fraction (HMF) and sunflower oil (SFO) was studied by following nucleation with laser-polarized turbidimetry. The initial crystals were photographed, and their thermal and polymorphic behaviors, as well as chemical composition, were investigated by calorimetry, X-ray diffraction, and capillary gas chromatography. Activation energies of nucleation were calculated using the Fisher−Turnbull equation. Despite small differences in Mettler dropping points for different ratios of SFO to HMF, induction times were significantly different between samples and were shorter at a slow cooling rate for the same supercooling. Rapidly cooled …

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Blend Effects In The Toxicity Of The Essential Oil Constituents Of Ocimum Kilimandscharicum And Ocimum Kenyense (Labiateae) On Two Post-Harvest Insect Pests, Jembere Bekele, Ahmed Hassanali Jun 2001

Blend Effects In The Toxicity Of The Essential Oil Constituents Of Ocimum Kilimandscharicum And Ocimum Kenyense (Labiateae) On Two Post-Harvest Insect Pests, Jembere Bekele, Ahmed Hassanali

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The lethal toxicity of major components of the essential oils of Ocimum kilimandscharicum and O. kenyense and of selected blends of these against Sitophilus zeamais and Rhyzopertha dominica were compared with those of the full blends of the essential oils. The compounds were assayed in amounts and proportions present in the minimum 100% lethal dose of the oils. Whereas a major component of O. kilimandscharicum was found to be largely responsible for the toxic action of its essential oil against R. dominica, the results with the other treatments indicated that the toxic action of the essential oils were due to …

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Habitat Fragmentation And Native Bees: A Premature Verdict?, James H. Cane Jan 2001

Habitat Fragmentation And Native Bees: A Premature Verdict?, James H. Cane

All PIRU Publications

No abstract provided.

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Causes And Extent Of Declines Among Native North American Invertebrate Pollinators: Detection, Evidence, And Consequences, James H. Cane, Vincent J. Tepedino Jan 2001

Causes And Extent Of Declines Among Native North American Invertebrate Pollinators: Detection, Evidence, And Consequences, James H. Cane, Vincent J. Tepedino

All PIRU Publications

No abstract provided.

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Changes In The Distribution Of Lepidopteran Maize Stemborers In Kenya From The 1950s To 1990s, Zhou Guofa, William A. Overholt, Moses B. Mochiah Jan 2001

Changes In The Distribution Of Lepidopteran Maize Stemborers In Kenya From The 1950s To 1990s, Zhou Guofa, William A. Overholt, Moses B. Mochiah

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Three hundred and ninety-two maize fields in the southern arable zone of Kenya were sampled for lepidopteran cereal stemborers from 1996-2000. Chilo partelhis (Swinhoe) was the most abundant stemborer, and was found at all locations with elevations below 1500 m, and at some locations between 1500 and 2300 m. The highest density of C. partelhis was in the semi-arid ecological zone of eastern Kenya. Chilo orichalcociliellus (Strand) was found in the lowland southern coastal area, and a few inland sites on the border of Tanzania in southeastern Kenya. Busseola fusca Fuller was dominant in highland areas. In the Lake Victoria …

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Spatial And Temporal Distribution Of Tsetse Fly Trap Catches At Nguruman, Southwest Kenya, A. Odulaja, J. Baumgärtner, S. Mihok, I. M. Abu-Zinid Jan 2001

Spatial And Temporal Distribution Of Tsetse Fly Trap Catches At Nguruman, Southwest Kenya, A. Odulaja, J. Baumgärtner, S. Mihok, I. M. Abu-Zinid

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Spatial and temporal dynamics of rapidly growing populations of tsetse flies at Nguruman, southwest Kenya during 1993-1995, were investigated, following six years of intensive population suppression with traps over a c. 100 km2 area. The two tsetse species present were randomly distributed in the short rainy season, but were aggregated in the dry and long rainy seasons. Maximum temperature was the dominant weather factor associated with the degree of aggregation. Trends in catches at 20 fixed sites along an 18 km north-south axis were weakly correlated between locations, possibly representing population sub-structuring. In particular, trends in population change were poorly …

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Distribution And Abundance, In Maize And Sorghum, Of Lepidopteran Stemborers And Associated Indigenous Parasitoids In Zanzibar, E. I. Nlyibigira, Z. S. Abdallah, W. A. Overholt Jan 2001

Distribution And Abundance, In Maize And Sorghum, Of Lepidopteran Stemborers And Associated Indigenous Parasitoids In Zanzibar, E. I. Nlyibigira, Z. S. Abdallah, W. A. Overholt

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Studies to determine the relative abundance and distribution of stemborer species and their associated parasitoids in maize and sorghum were carried out during the 1995-1996 and 19992000 cropping seasons on Unguja and Pemba, the two main islands of Zanzibar. Three stemborer species were found on both islands in maize and sorghum, with the exotic species Chilo partellns (Swinhoe) (Crambidae) being the most abundant and widely distributed species, accounting for 75.3 % of stemborer attack. It was followed by Sesamia calamistis Hampson (Noctuidae) and C/i. oriclialcociliellus Strand (Crambidae). Stemborer abundance was significantly higher in Pemba (1.47 ± 0.20) than Unguja (0.85 …

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Biosystematics Of The Psyttalia Concolor Species Complex (Hymenoptera: Braconidae: Opiinae): The Identity Of Populations Attacking Ceratitis Capitata (Diptera: Tephritidae) In Coffee In Kenya, S. W. Kimani-Njogu, M. K. Trostle, R. A. Wharton, J. B. Woolley, A. Raspi Jan 2001

Biosystematics Of The Psyttalia Concolor Species Complex (Hymenoptera: Braconidae: Opiinae): The Identity Of Populations Attacking Ceratitis Capitata (Diptera: Tephritidae) In Coffee In Kenya, S. W. Kimani-Njogu, M. K. Trostle, R. A. Wharton, J. B. Woolley, A. Raspi

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The identity of a species of Psyttalia, a parasitoid of tephritid fruit flies in Kenya, was investigated. Individuals reared from coffee infested with Ceratitis capitata (Wiedemann) (Medfly) and two other tephritid species in Kenya were compared with individuals of Psyttalia concolor (Szépligeti) from a laboratory culture in Italy used in augmentative biological control of olive fly, Bactrocera oleae (Gmelin). Reciprocal crosses showed full compatibility, with production of viable female offspring. A preliminary morphometric analysis demonstrated that most individuals originating from Italy could be separated from most of those from Kenya based largely on differences in overall size.

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Greenhouse Trials Of New Bacillus Thuringiensis Isolates For Control Of Chilo Partellus Larvae In Sorghum, Michael Brownbridge Jan 2001

Greenhouse Trials Of New Bacillus Thuringiensis Isolates For Control Of Chilo Partellus Larvae In Sorghum, Michael Brownbridge

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Eight new Bacillus thuringiensis Berliner (Bt) isolates originally recovered from different source materials and geographic locations in Kenya were tested against Chilo partellus (Swinhoe) on sorghum grown in a greenhouse. All isolates had been demonstrated previously to be toxic to this pest. Bt strains were cultured in a liquid growth medium and preserved as powders for experimental application. Three-week-old sorghum plants (4-6 leaves) were artificially infested with 20 neonate C. partellus and sprayed 24 h later with Bt suspensions. Non-infested sorghum and infested non-treated sorghum served as the comparative checks within each experimental trial. Plant development and dead-heart formation were …

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Comparative Development, Longevity And Population Growth Of Exotic And Native Parasitoids Of Lepidopteran Cereal Stemborers In Kenya, J. C. Mbapila, W. A. Overholt Jan 2001

Comparative Development, Longevity And Population Growth Of Exotic And Native Parasitoids Of Lepidopteran Cereal Stemborers In Kenya, J. C. Mbapila, W. A. Overholt

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Studies on the effect of temperature on the development, longevity and population growth of Cotesia flavipes Cameron and Cotesia sesamiae (Cameron) indicated that the development of both Cotesia spp. from oviposition to cocoon formation and adult emergence was inversely related to temperature. The longevity of the parasitoids was also inversely related to temperature. Both parasitoids lived longer when moisture and food (agar + honey/water) were provided. The mean number of females and total adult progeny produced by C. flavipes on two host species were, in most cases, higher than C. sesamiae. The intrinsic rate of natural increase of C. flavipes …

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Release Of Cotesia Flavipes Cameron For Biological Control Of Cereal Stemborers In Two Ecological Zones In Mozambique, D. Cugala, W. A. Overholt, L. Santos, D. Giga Jan 2001

Release Of Cotesia Flavipes Cameron For Biological Control Of Cereal Stemborers In Two Ecological Zones In Mozambique, D. Cugala, W. A. Overholt, L. Santos, D. Giga

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Cotesiaflavipes Cameron (Hymenoptera: Braconidae), a gregarious larval endoparasitoid of Cliilo parleUus (Swinhoe) (Lepidoptera: Crambidae) and other stemborers in the Indo-Australian region, was released in Mozambique for the first time in 1996. Before its release, countrywide surveys on stemborers and their natural enemies were conducted in several places. However, all led to the same conclusion: that Ch. partellns was the most abundant stemborer at the majority of locations, and that the rate of larval parasitism was very low (< 5 %). To evaluate the effect of stemborer species composition on- the establishment of Co. flavipes, two releases were made at two agroecologically different sites during the 1998/1999 and 1999/2000 growing seasons. Cotesiaflavipes was recovered from all the three stemborer species found at each site during the season of release and a year later. However, the rates of parasitism were very low, ranging from 0.6 to 1.9 % on Cli. partellus, 3.2 % on Sesamia calamislis Hampson (Lepidoptera: Noctuidae) and 2.6 % on Busseolafiisca Fuller (Lepidoptera: Noctuidae). The native natural enemy, Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) was the most common larval parasitoid at the two sites. The recoveries of Co. flavipes during the release period and a year later indicate that this exotic parasitoid has become established at the two locations in the southern and central regipns of Mozambique, in spite of differences in stemborer species composition. However, it is too early to evaluate the impact of Co.flai'ipes on the stemborer populations. © 2001 ICIPE.

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Cereal Stemborer Species Complex And Establishment Of Cotesia Flavipes Cameron In Eastern Uganda, T. Matama-Kauma, S. Kyamanywa, J. A. Ocwang, C. O. Omwega, H. R. Willson Jan 2001

Cereal Stemborer Species Complex And Establishment Of Cotesia Flavipes Cameron In Eastern Uganda, T. Matama-Kauma, S. Kyamanywa, J. A. Ocwang, C. O. Omwega, H. R. Willson

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Studies were conducted in two districts of eastern Uganda from 1997 to 1999 to introduce and monitor the establishment of an exotic parasitoid, Cotesia flavipes Cameron (Hymenoptera: Braconidae), for the control of the stemborer Chilo partellns (Swinhoe) (Lepidoptera: Pyralidae), and also to determine the stemborer species complex in maize and sorghum. The study confirmed the presence of four important stemborers, two pyralids Ch. parlellus and Eldana saccharina Walker and two noctuids, Busseola fusca Fuller and Sesamia calamistis Hampson. Chilo partellus was dominant, constituting 53-88% of stemborers found followed by B.fiisca at 8-37 %. The most abundant local parasitoid was the …

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Variation In Lipophorin Titres During Development In Solitarious And Gregarious Schistocerca Gregaria (Forskàl) (Orthoptera: Acrididae), D. O. Ogoyi, E. O. Osir Jan 2001

Variation In Lipophorin Titres During Development In Solitarious And Gregarious Schistocerca Gregaria (Forskàl) (Orthoptera: Acrididae), D. O. Ogoyi, E. O. Osir

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The levels of lipophorin, the principal insect haemolymph lipoprotein, were estimated during the development of solitary and gregarious phases of Schistocerca gregaria using single radial immunodiffusion. In the gregarious phase, lipophorin titres ranged from 6.69 ±0.57 mg/ml in the 3rd nymphal instar to 14.42 ±2.04 mg/ml in mature adults. The titres in the solitary phase were 3.33 ± 0.59 mg/ml in the 3rd nymphal instar and 8.44 + 0.67 mg/ml in mature adults. Peak lipophorin titres occurred in mature adults (14.42 ±2.04 mg/ml) and 5th nymphal instar (8.75 ±0.25 mg/ml) for gregarious and solitary locusts, respectively. Gregarious locusts had significantly …

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Relationships Of Stemborer Damage And Plant Physical Conditions To Maize Yield In A Semi-Arid Zone Of Eastern Kenya, Josephine Moraa Songa, Zhou Guofa, William Allan Overholt Jan 2001

Relationships Of Stemborer Damage And Plant Physical Conditions To Maize Yield In A Semi-Arid Zone Of Eastern Kenya, Josephine Moraa Songa, Zhou Guofa, William Allan Overholt

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A field survey on maize stemborers, stemborer damage, maize plant physical conditions, and maize yield was conducted in eastern Kenya under natural conditions. Chilo partellus was the dominant stemborer accounting for 89.5 % of all borers. Stemborer damage greatly reduced maize yield, with tunnel lengths greater than 20 cm causing a 40 % reduction of potential yield. A 33 % yield loss was found in plants with more than one stemborer exit hole. Each stemborer (at harvest time) was correlated with a 8-10 % yield loss. Good plant physical characteristics significantly increased grain yield. Principle component analysis showed that stemborer …

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Polymorphism For Wolbachia Infections In Eastern And Southern African Cotesia Sesamiae (Cameron) (Hymenoptera: Braconidae) Populations, Adele J. Ngi-Song, Moses B. Mochiah Jan 2001

Polymorphism For Wolbachia Infections In Eastern And Southern African Cotesia Sesamiae (Cameron) (Hymenoptera: Braconidae) Populations, Adele J. Ngi-Song, Moses B. Mochiah

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Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) is an indigenous, gregarious, larval endo/parasitoid which is widely distributed in Africa and attacks mid- to late instars of stemborers. There is renewed interest in using Co. sesamiae for biological control to reduce the problems caused by stemborers. However, Wolbachia sp., a bacterial symbiont of some populations of Co. sesamiae, poses some threat to the successful use of the parasitoid for stemborer control. This bacterium's common effect is cytoplasmic incompatibility, between infected males and uninfected females. Polymerase chain reaction (PCR) tests were carried out on parasitoid samples collected from 5 locations in Kenya and 8 …

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Distribution And Species Composition Of Cereal Stemborers In The Eastern Zone Of Tanzania, E. Nsami, B. Pallangyo, V. Mcoo, C. O. Omwega Jan 2001

Distribution And Species Composition Of Cereal Stemborers In The Eastern Zone Of Tanzania, E. Nsami, B. Pallangyo, V. Mcoo, C. O. Omwega

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A survey was conducted in the four regions of Tanga, Morogoro, Coast and Dar es Salaam in eastern Tanzania to determine the distribution and species composition of cereal stemborers and their natural enemies. A total of 22 fields were sampled in Tanga, 28 in Morogoro, 17 in Coast and one in Dar es Salaam. Chilo parlellns was found to be the predominant species, accounting for 80 % of all stemborers collected. Bnsseolafnsca, Sesamia calamistis and Chilo orichalcociliellus made up 15,4 and less than 1 % of the stemborers collected respectively. Infestation levels varied with the age of the plants, whereby …

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Farmers’ Perceptions Of Importance, Control Methods And Natural Enemies Of Maize Stemborers At The Kenya Coast, M. J. Bonhof, A. Van Huis, F. G. Kiros, N. Dlbogo Jan 2001

Farmers’ Perceptions Of Importance, Control Methods And Natural Enemies Of Maize Stemborers At The Kenya Coast, M. J. Bonhof, A. Van Huis, F. G. Kiros, N. Dlbogo

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A survey among 240 resource-poor farmers at the Kenya coast indicated that insect pests were considered to be the main production constraint. Over 70% of respondents mentioned stemborers to be the most important insect pest. Unlike the eggs and adults, stemborer larvae and pupae were frequently seen by farmers. Alternative gramineous host plants for pests were common near maize fields and were often not destroyed until after the first rains. Nearly all farmers left dry stems and stubble in the field after harvest. Farmers knew of many methods for controlling stemborers, but only 32 and 56% of farmers in Kilifi …

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Impact Of Solar Radiation Rainfall And Cannibalism On Disappearance Of Maize Stemborers In Kenya, M. J. Bonhof, W. A. Overholt Jan 2001

Impact Of Solar Radiation Rainfall And Cannibalism On Disappearance Of Maize Stemborers In Kenya, M. J. Bonhof, W. A. Overholt

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The effect of solar radiation, rainfall and cannibalism on the disappearance of eggs and larvae of the cereal stemborer Chilo partellus (Swinhoe) were studied. Disappearance and nonviability of egg batches was higher on plants exposed to solar radiation than on shaded plants. Significantly fewer small larvae were recovered from plants exposed to rainfall than from shielded plants. Cannibalism among larvae of the same size was not common except at high larval densities. Contrary to the common belief that disappearance is the result of prédation, these studies show that solar radiation and rainfall might also play an important role in the …

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Properties Of A Factor In Eland Plasma That Inhibits Transformation Of Bloodstream-Form Trypanosoma Brucei Brucei, E. K. Nguu, E. O. Osir Jan 2001

Properties Of A Factor In Eland Plasma That Inhibits Transformation Of Bloodstream-Form Trypanosoma Brucei Brucei, E. K. Nguu, E. O. Osir

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Fresh plasma from the African eland, Taiirotragus oryx, contains a factor that inhibits the transformation of bloodstream-form Trypanosma bnicei bntcei into procyclic (midgut) forms. Heating of the plasma at 42, 50 and 60 °C for 30 min resulted in a 20, 38 and 40% loss of inhibitor activity respectively, whereas only negligible loss occurred below 42 C. Similarly, one and four freeze-thawing cycles resulted in 32 and 60% loss of activity respectively. Inactivation of the inhibitor activity, which occurred rapidly during storage (for example, 80% loss after 7 days at -20 °C) could not be stopped by the addition of …

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