Open Access. Powered by Scholars. Published by Universities.®

Life Sciences Commons™

Open Access. Powered by Scholars. Published by Universities.®

All Peer-Reviewed Publications

Discipline
Keyword
Publication Year
File Type

Articles 1291 - 1320 of 1443

Full-Text Articles in Life Sciences

Spatial Distribution And Habitat Characterization Of Anopheline Mosquito Larvae In Western Kenya, Noboru Minakawa, Clifford M. Mutero, John I. Githure, John C. Beier, Guiyun Yan Jan 1999

Spatial Distribution And Habitat Characterization Of Anopheline Mosquito Larvae In Western Kenya, Noboru Minakawa, Clifford M. Mutero, John I. Githure, John C. Beier, Guiyun Yan

All Peer-Reviewed Publications

Studies were conducted to characterize larval habitats of anopheline mosquitoes and to analyze spatial heterogeneity of mosquito species in the Suba District of western Kenya. A total of 128 aquatic habitats containing mosquito larvae were sampled, and 2,209 anopheline and 10,538 culicine larvae were collected. The habitats were characterized based on size, pH, distance to the nearest house and to the shore of Lake Victoria, coverage of canopy, surface debris, algae and emergent plants, turbidity, substrate, and habitat types. Microscopic identification of third and fourth-instar anopheline larvae did not yield any Anopheles funestus or other anophelines. A total of 829 …

Go to article

Genetic Relationships Among Subspecies Of Vigna Unguiculata (L.) Walp. Based On Allozyme Variation, R. S. Pasquet Jan 1999

Genetic Relationships Among Subspecies Of Vigna Unguiculata (L.) Walp. Based On Allozyme Variation, R. S. Pasquet

All Peer-Reviewed Publications

The cowpea [Vigna unguiculata (L.) Walp.] is a morphologically and genetically variable species composed of wild perennial, wild annual, and cultivated forms that are mainly used for edible seeds and pods. In this study, genetic variation in 199 germplasm accessions of wild and cultivated cowpea was evaluated using an allozyme analysis. The results from this survey showed that wild cowpea exhibits genetic variation perfectly fitted with the existing morphological classification. The cowpea gene-pool is characterized by its unusually large size. It encompasses taxa (ranked as subspecies) that could be considered as different species considering the high genetic distances observed between …

Go to article

Intra- And Interspecific Aggregation Responses Of Locusta Migratoria Migratorioides And Schistocerca Gregaria And A Comparison Of Their Pheromone Emissions, Abdoulaye Niassy, Baldwyn Torto, Peter G.N. Njagi, Ahmed Hassanali, Daniel Obeng-Ofori, Jonathan N. Ayertey Jan 1999

Intra- And Interspecific Aggregation Responses Of Locusta Migratoria Migratorioides And Schistocerca Gregaria And A Comparison Of Their Pheromone Emissions, Abdoulaye Niassy, Baldwyn Torto, Peter G.N. Njagi, Ahmed Hassanali, Daniel Obeng-Ofori, Jonathan N. Ayertey

All Peer-Reviewed Publications

Gregarious nymphs of Schistocerca gregaria and Locusta migratoria migratorioides are often seen to march together in common bands in the field. In the present study, the intraspecific aggregation responses of nymphal and older stages of the two insects were compared with their interspecific responses. Unlike S. gregaria, L. m. migratorioides shows a lesser pattern of stage and sex differentiation in its aggregation pheromone biology. Thus, although fifth-instar nymphs did not respond significantly to the adult pheromone, adults responded significantly to the nymph pheromone. No cross- stage aggregative responses occur in S. gregaria. In the adults of S. gregaria, production of …

Go to article

Evidence For Additional Pheromonal Components Mediating Oviposition Aggregation In Schistocerca Gregaria, Baldwyn Torto, Yousif O.H. Assad, Peter G.N. Njagi, Ahmed Hassanali Jan 1999

Evidence For Additional Pheromonal Components Mediating Oviposition Aggregation In Schistocerca Gregaria, Baldwyn Torto, Yousif O.H. Assad, Peter G.N. Njagi, Ahmed Hassanali

All Peer-Reviewed Publications

Oviposition responses of gregarious adult gravid females of the desert locust Schistocerca gregaria to sand previously used for oviposition by gregarious females (contaminated sand, with eggs and froth removed) and to sterilized sand (noncontaminated sand) were compared in bioassays. Gregarious females preferentially oviposited into contaminated sand. The number of egg pods laid by the females was found to correlate with the frequency of use of the contaminated sand for oviposition. Charcoal-trapped volatiles from the contaminated sand also elicited similar responses from gregarious females. Gas chromatography-electroantennographic detection (GC-EAD) analysis of the trapped volatiles revealed the presence of three electrophysiologically active compounds …

Go to article

Development Of Odour-Baited Traps For Glossina Swynnertoni (Diptera: Glossinidae), P. N. Ndegwa, S. Mihok Jan 1999

Development Of Odour-Baited Traps For Glossina Swynnertoni (Diptera: Glossinidae), P. N. Ndegwa, S. Mihok

All Peer-Reviewed Publications

Three new prototype traps, (S1-S3), were developed during studies of the behavioural ecology of Glossina swynnertoni Austen in Kenya and Tanzania. The traps were compared in latin square experiments relative to the regular biconical trap as a standard and a selection of other conventional tsetse traps. Observations were also made on fly behaviour in the vicinity of traps using electric nets and sticky materials. When baited with acetone and 1-octen-3-ol, the S1 trap was 3.5 times as effective in catching G. swynnertoni in Kenya as the biconical trap. In Tanzania, the relative performance of the S1 and biconical traps differed; …

Go to article

Potential Of The Entomopathogenic Fungus, Metarhizium Anisopliae (Metsch.) Sorokin For Control Of The Legume Flower Thrips, Megalurothrips Sjostedti (Trybom) On Cowpea In Kenya, S. Ekesi, N. K. Maniania, K. Ampong-Nyarko, I. Onu Nov 1998

Potential Of The Entomopathogenic Fungus, Metarhizium Anisopliae (Metsch.) Sorokin For Control Of The Legume Flower Thrips, Megalurothrips Sjostedti (Trybom) On Cowpea In Kenya, S. Ekesi, N. K. Maniania, K. Ampong-Nyarko, I. Onu

All Peer-Reviewed Publications

Field experiments were conducted at Mbita, western Kenya for two seasons to evaluate the potential of the entomopathogenic fungus, Metarhizium anisopliae (Metsh.) Sorokin, for biological control of the legume flower thrips, Megalurothrips sjostedti (Trybom), on cowpea. An ultra-low-volume (ULV) oil/aqueous formulation and a high-volume (HV) aqueous formulation of conidia were applied three times each at two concentrations of 1 x 1011 and 1 x 1013 conidia ha-1. Compared with the untreated controls, both formulations significantly reduced thrips populations and plant damage in both seasons. Adult insects collected from fungal-treated plots and reared in the laboratory showed a high mortality due …

Go to article

Expression Of Chromosomally Insertedbacillus Thuringiensis Israelensistoxin Genes Inbacillus Sphaericus, E. Bar, N. Sandler, M. Makayoto, A. Keynan Nov 1998

Expression Of Chromosomally Insertedbacillus Thuringiensis Israelensistoxin Genes Inbacillus Sphaericus, E. Bar, N. Sandler, M. Makayoto, A. Keynan

All Peer-Reviewed Publications

Bacillus thuringiensis israelensisδ-endotoxin genes were inserted into transposon Tn917in plasmid pTV51Ts and cloned into the chromosome ofBacillus sphaericus2362. Many of the transformants reacted with antibody to the 135-, 128-, 65-, and 28-kDaB.t.israelensistoxin proteins and were approximately 10 times more toxic toA. aegyptilarvae than the untransformed host. Some of the transformants differed physiologically and morphologically from the wild-typeB. sphaericus.The toxicity of the transformed phenotype was maintained through many transfers in the absence of selective pressure. © 1998 Academic Press.

Go to article

Evaluation Of Mortality Factors And Risk Analysis For The Design Of An Integrated Pest Management System, Olivier Roux, Johann Baumgärtner Jun 1998

Evaluation Of Mortality Factors And Risk Analysis For The Design Of An Integrated Pest Management System, Olivier Roux, Johann Baumgärtner

All Peer-Reviewed Publications

A probabilistic approach of survival analysis based on the theory of competing risks was applied to the potato tuber moth Phthorimaea operculella (Zeller) affecting tubers in Tunisian rustic stores. Exponential curve of death, i.e. constant force of mortality functions were used in a case study on a cohort time basis. The additive property of crude cause-specific forces of mortality is used to combine mortality factors, which permits to judge different control strategies. In an integrated pest management perspective, the effect of basic mortalities, i.e innate and dispersal related mortalities is recombined with native natural enemies. Thereafter, we calculate the force …

Go to article

Isozyme Polymorphism Within Section Reticulatae Of Genus Vigna (Tribe Phaseoleae: Fabaceae), Maimouna Garba, Rémy S. Pasquet Apr 1998

Isozyme Polymorphism Within Section Reticulatae Of Genus Vigna (Tribe Phaseoleae: Fabaceae), Maimouna Garba, Rémy S. Pasquet

All Peer-Reviewed Publications

An electrophoretic comparison of variation at 30 isozyme loci was performed for 45 accessions from genus Vigna, section reticulatae. Within the section level, these results fitted the nomenclature used. Within V. reticulata, variability was organized geographically and the West African weedy V. reticulata genetically was different from West African wild V. reticulata.

Go to article

Electrophoretic And Phylogenetic Analyses Of Selected Allopatric Populations Of The Cotesia Flavipes Complex (Hymenoptera: Braconidae), Parasitoids Of Cereal Stemborers, Susan W. Kimani-Njogu, William A. Overholt, James B. Woolley, Charles O. Omwega Apr 1998

Electrophoretic And Phylogenetic Analyses Of Selected Allopatric Populations Of The Cotesia Flavipes Complex (Hymenoptera: Braconidae), Parasitoids Of Cereal Stemborers, Susan W. Kimani-Njogu, William A. Overholt, James B. Woolley, Charles O. Omwega

All Peer-Reviewed Publications

Electrophoretic studies were conducted on the Cotesia flavipes Cameron complex and Cotesia glomerata L. (Hymenoptera: Braconidae). Esterase, glucosephosphate isomerase, hexokinase, sorbital dehydrogenase and phosphogluconate dehydrogenase had fixed alleles for the three species and could be used to distinguish them. Cotesia chilonis (Matsumura) and Cotesia sesamiae (Cameron), have a genetic identity value characteristic of distinct species (Nei's genetic identity, I = 0.587). Cladistic analysis of the allozyme data indicated that allopatric populations currently included in C. flavipes may not be a monophyletic group.

Go to article

Suitability Of Busseola Fusca And Sesamia Calamistis (Lepidoptera: Noctuidae) For The Development Of Two Populations Of Cotesia Sesamiae (Hymenoptera: Braconidae) In Kenya, A. J. Ngi-Song, W. A. Overholt, R. Stouthamer Jan 1998

Suitability Of Busseola Fusca And Sesamia Calamistis (Lepidoptera: Noctuidae) For The Development Of Two Populations Of Cotesia Sesamiae (Hymenoptera: Braconidae) In Kenya, A. J. Ngi-Song, W. A. Overholt, R. Stouthamer

All Peer-Reviewed Publications

The suitability of Sesamia calamistis Hampson and Busseola fusca (Fuller) for the development of two geographical populations of Cotesia sesamiae (Cameron) was examined in the laboratory. One population of the parasitoid was collected from the coast of Kenya and the other from the inland. Both populations of the parasitoid could develop on S. calamistis. On B. fusca, the inland population of C. sesamiae was able to develop, while the population from the coastal area of Kenya was encapsulated. Mating studies revealed that the two parasitoid populations were partially reproductively isolated. Unidirectional incompatibility, possibly caused by the Wolbachia infection, was observed …

Go to article

Morphological Study Of Cultivated Cowpea Vigna Unguiculata (L.) Walp. Importance Of Ovule Number And Definition Of Cv Gr Melanophthalmus, Rémy Stéphane Pasquet Jan 1998

Morphological Study Of Cultivated Cowpea Vigna Unguiculata (L.) Walp. Importance Of Ovule Number And Definition Of Cv Gr Melanophthalmus, Rémy Stéphane Pasquet

All Peer-Reviewed Publications

More than 400 cultivated cowpea accessions were studied using 29 morphophysiological characters. The analysis of data contrasts evolved cultivars and more primitive cultivars (and wild forms) according to seed size on the one hand and early and late flowering (under inductive conditions) on the other hand. The latter character is markedly correlated with ovule number. Photosensitive and early-flowering photoindependent cultivars have 11-17 ovules per pod and late flowering photoindependent cultivars have 16-25 ovules per pod. The analysis leads to assigning the accessions studied to the following different cultigroups: cv gr Unguiculata, cv gr Sesquipedalis, cv gr Biflora and cv gr …

Go to article

Olfactory Responses Of Glossina Fuscipes Fuscipes (Diptera: Glossinidae) To The Monitor Lizard Varanus Niloticus Niloticus, M. M. Mohamed-Ahmed Jan 1998

Olfactory Responses Of Glossina Fuscipes Fuscipes (Diptera: Glossinidae) To The Monitor Lizard Varanus Niloticus Niloticus, M. M. Mohamed-Ahmed

All Peer-Reviewed Publications

Visual and olfactory responses of Glossina fuscipes fuscipes Newstead to the monitor lizard, Varanus niloticus niloticus Laurenti were studied using various catching devices near Lake Victoria, Kenya. Electric nets baited with visible lizards caught more males (x2.1) and significantly more females (x2.0) than unbaited nets. Lizards concealed in electrified black Pvc pipe models, simulating the shape and size of a monitor lizard, increased significantly the catches of tsetse by 2.1 times. Fresh lizard urine dispensed at an evaporation rate of 500 to 1000 mg/h also increased significantly the catches of flies at biconical traps, electrified models and electric nets. Identification …

Go to article

Evidence Of Antibiosis Resistance To The Spotted Stemborer, Chilo Partellus (Swinhoe) In A Maize (Zea Mays L.) Population, C. J.M. Mutinda, K. N. Saxena, S. O. Ajala, P. O. Aviecho Jan 1998

Evidence Of Antibiosis Resistance To The Spotted Stemborer, Chilo Partellus (Swinhoe) In A Maize (Zea Mays L.) Population, C. J.M. Mutinda, K. N. Saxena, S. O. Ajala, P. O. Aviecho

All Peer-Reviewed Publications

S2 line and S2 test-cross recurrent selection procedures were initiated to improve the resistance of a maize (Zen mays L.) population to the spotted stemborer, Chllo partclltis (Swinhoe) (Lepidoptera: Pyralidae). Thirty-five selections developed from the population were evaluated for resistance to the stemborer in western Kenya. Resistance was rated according to leaf feeding (LF), stem tunnelling (ST) and deadheart formation (DH) following artificial infestation with first-instar C. pnrtcUus. Larval establishment and growth were also assessed. The reduction in foliar damage ratings, percentage stem length tunnelled, and percentage of plants showing deadheart after one cycle of recurrent selection were 4.38 %, …

Go to article

Cost Of Tsetse Trapping Using The Ng2g Trap: A Case Study In Kenya, George Tombe Lako Jan 1998

Cost Of Tsetse Trapping Using The Ng2g Trap: A Case Study In Kenya, George Tombe Lako

All Peer-Reviewed Publications

In a study to determine the costs of tsetse trapping in terms of construction materials, labour, transport and maintenance, two hundred forty-six traps used to control Glossina pallidipes in an area of 100 square kilometres at Nguruman, Kenya were evaluated from November 1990 to July 1992. The total cost of materials, labour and servicing per trap per year, was US$ 30.6 which, at that time was equivalent to 1071 Kenya shillings. ©1998ICIPE.

Go to article

Effect Of Species, Age, And Sex Of Tsetse On Response To Infection By Metarhizium Anisopliae, Nguya K. Maniania, Adedapo Odulaja Jan 1998

Effect Of Species, Age, And Sex Of Tsetse On Response To Infection By Metarhizium Anisopliae, Nguya K. Maniania, Adedapo Odulaja

All Peer-Reviewed Publications

Laboratory studies were carried out to determine the effect of sex and age on the susceptibility of tsetse, Glossina morsitans morsitans and G. m. centralis, to the entomopathogenic fungus, Metarhizium anisopliae. Both species of host flies were susceptible to fungal infection. Female flies were generally more susceptible than male flies. Three host ages (40, 20, and <1 day-old) were used; the youngest group was most resistant to fungal infection. Interactions between species, sex and age were significant on many occasions. Age usually accounted for the largest variability in mortality, followed by sex. All flies of age 40 days died between 7 and 8 days after infection whereas some of the younger flies, especially age 0, lived longer than 10 days. Log10 day probit (LDP) mortality regressions fitted well to most of the data sets. LDP slopes were significant and high, ranging between 4.3 and 12.8, indicating a generally high mortality rate of increase over days. The slopes differed significantly between species, sexes, and ages, but grouping by age was more intra homogeneous than by species or sex. The 50% lethal time mortalities (LT50) ranged between 4 and 7 days for age 0, 3 and 6 days for age 20, and about 5 days for age 40. Corresponding ranges of the LT95 were 8 to 20, 5 to 10, and 6 to 7 days for ages 0, 20 and 40, respectively. The significance of these results in the fungal disease transmission by tsetse is discussed.

Go to article

Brood Guarding Behavior And Life History Characteristics Of Goniozus Indicus Ashmead (Hymenoptera: Bethylidae), A Larval Ectoparasitoid Of Lepidopteran Stemborers, Keiji Takasu, William A. Overholt Jan 1998

Brood Guarding Behavior And Life History Characteristics Of Goniozus Indicus Ashmead (Hymenoptera: Bethylidae), A Larval Ectoparasitoid Of Lepidopteran Stemborers, Keiji Takasu, William A. Overholt

All Peer-Reviewed Publications

Brood guarding behavior and life history characteristics of Goniozus indicus Ashmead (Hymenoptera: Bethylidae) were examined in the laboratory. Longevity was increased when females were provided host frass, and females reared in association with hosts lived longer than females maintained separately from hosts. Females that were allowed free access to hosts oviposited at intervals of one to eight days and never parasitized more than one host per day. Females laid 5-25 eggs per host, and life time fecundity was 15-52 eggs at 25°C, 7-60 eggs at 28°C, and 5-25 eggs at 31°C. Females exhibited egg guarding behavior, remaining with the hosts …

Go to article

The Effects Of A Dna Virus Infection On The Reproductive Otential Of Female Tsetse Flies, Glossina Morsitans Centralis And Glossina Morsitans Morsitans (Diptera: Glossinidae), Rosemary C. Sang, Walter G.Z.O. Jura, Leonard H. Otieno, Richard W. Mwangi Jan 1998

The Effects Of A Dna Virus Infection On The Reproductive Otential Of Female Tsetse Flies, Glossina Morsitans Centralis And Glossina Morsitans Morsitans (Diptera: Glossinidae), Rosemary C. Sang, Walter G.Z.O. Jura, Leonard H. Otieno, Richard W. Mwangi

All Peer-Reviewed Publications

Reproductive anomalies associated with the tsetse DNA virus infection in the female tsetse hosts, Glossina morsitans centralis Machado and Glossina morsitans morsitans Westwood, inoculated with the virus during the 3rd instar larval stage were studied and the data compared to those obtained from the control females injected with sterile physiological saline. Virus infected flies had significantly longer first and second pregnancy cycles (P<0.0001) and produced pupae that were of significantly less weight in milligrams (P<-0.0001) compared to controls. Transmission of the virus to progeny was not absolute and only 21% of G. m. centralis and 48% of G. m. morsitans first progeny flies from infected females developed salivary gland hypertrophy as a result of transmission from mother to progeny. The virus infected females produced significantly fewere pupae compared to the controls during the experimental period (P<0.00001).

Go to article

Fat Body Triacylglycerol Lipase In Solitary And Gregarious Phases Of Schistocerca Gregaria (Forskal) (Orthoptera: Acrididae), Dorington O. Ogoyi, Ellie O. Osir, Norah K. Olembo Jan 1998

Fat Body Triacylglycerol Lipase In Solitary And Gregarious Phases Of Schistocerca Gregaria (Forskal) (Orthoptera: Acrididae), Dorington O. Ogoyi, Ellie O. Osir, Norah K. Olembo

All Peer-Reviewed Publications

The activities of the fat body triacylglycerol lipase were determined using 14C-trioleoylglycerol. Resting activities were estimated at 1.98 ± 0.24 and 1.95 ± 0.53 nmol free fatty acid (FFA)/hr/mg protein for gregarious and solitary locusts, respectively. Administration of adipokinetic hormone (AKH) I led to the activation of lipase with peak activities occurring after 30 min. In the solitary locusts, activities of 2.28 ± 0.16 and 2.30 ± 0.43 nmol FFA/hr/mg were obtained following administration of 10 and 2 pmol AKH I, respectively. In the gregarious locusts, enzyme activities of 3.17 ± 0.66 and 2.47 ± 0.39 nmol FFA/hr/mg were obtained …

Go to article

The Magnitude Of Site And Time Interaction Effect In Tsetse Fly (Diptera: Glossinidae) Trap Catches, A. Odulaja, S. Mihok, I. M. Abu-Zinid Jan 1998

The Magnitude Of Site And Time Interaction Effect In Tsetse Fly (Diptera: Glossinidae) Trap Catches, A. Odulaja, S. Mihok, I. M. Abu-Zinid

All Peer-Reviewed Publications

Site and time effects are important factors determining trap catches of tsetse flies. These factors may interact significantly and therefore confound interpretation of time series data used for population monitoring. We therefore investigated the magnitude and importance of site x time interactions in trap catches of Glossina pallidipes Austen and G. longipennis Corti using a 2200 trap-days (400 trap-months) data set. The interaction was found to be significant (P < 0.05) in 46-100% of the combinations of different numbers of months and sites between 2 and 12. The mean percent variance due to the interaction ranged between 4% and 28% for G. pallidipes and 12% and 36% for G. longipennis. The interaction was usually less important than the effect of site alone but more important than the effect of time alone. These results suggest that tsetse researchers should examine critically the adequacy of existing approaches to population monitoring with traps and to testing new traps and odour baits.

Go to article

Short Report: Influence Of Centers For Disease Control Light Trap Position, Relative To A Human-Baited Bed Net, On Catches Of Anopheles Gambiae And Culex Quinquefasciatus In Tanzania, Leonard E.G. Mboera, Japhet Kihonda, Marieta A.H. Braks, Bart G.J. Knols Jan 1998

Short Report: Influence Of Centers For Disease Control Light Trap Position, Relative To A Human-Baited Bed Net, On Catches Of Anopheles Gambiae And Culex Quinquefasciatus In Tanzania, Leonard E.G. Mboera, Japhet Kihonda, Marieta A.H. Braks, Bart G.J. Knols

All Peer-Reviewed Publications

The best position for Centers for Disease Control (Atlanta, GA) light traps, in relation to human-occupied bed nets for trapping of host-seeking Anopheles gambiae Giles and Culex quinquefasciatus Say mosquitoes, was determined in Tanzania. Significantly higher catches were recorded for both species when the trap was positioned at the foot end of the bed, near the top of the net. Parity rates were significantly higher near the top of the net than at the level of the host. Since trap position affects the catch size and the proportion of infectious mosquitoes therein, standardized use of this sampling technique for estimating …

Go to article

Comparison Of Nest Structure And Caste Parameters Of Sympatric Species Of Odontotermes (Termitidae, Macrotermitinae) In Kenya, J. P.E.C. Darlington Dec 1997

Comparison Of Nest Structure And Caste Parameters Of Sympatric Species Of Odontotermes (Termitidae, Macrotermitinae) In Kenya, J. P.E.C. Darlington

All Peer-Reviewed Publications

Four species of Odontotermes are common in semi-arid grassland around Kajiado. They all build centralised nests consisting of a cluster of discrete chambers housing the fungus combs. In at least one nest of each species all the chambers were measured and mapped, and the fungus combs extracted, dried and weighed. Three species, O. monodon, O. anceps and O. tanganicus, build 'classical' nests with open vertical shafts that link up underground, apparently acting as a ventilation system. The fourth species O. zambesiensis has no open shafts and no ventilation system. Each of the four species has fungus combs that are distinctly …

Go to article

Effects Of Juvenile Hormone Treatment On Phase Changes And Pheromone Production The Desert Locust, Schistocerca Gregaria (Forskal) (Orthoptera: Acrididae), Amer I. Tawfik, Ellie O. Osir, Ahmed Hassanali, Sayed H. Ismail Nov 1997

Effects Of Juvenile Hormone Treatment On Phase Changes And Pheromone Production The Desert Locust, Schistocerca Gregaria (Forskal) (Orthoptera: Acrididae), Amer I. Tawfik, Ellie O. Osir, Ahmed Hassanali, Sayed H. Ismail

All Peer-Reviewed Publications

The roles of juvenile hormone III (JH III) on phase changes and pheromone production were examined in laboratory-reared gregarious desert locust, Schistocerca gregaria (Forskal). The hormone was applied to 5th instar nymphs and newly emerged adult locusts. Generally, the 5th instar nymphs exhibited a higher sensitivity to hormone treatments than the adults. Hormone applications inhibited pheromone production (as measured by the amounts of phenylacetonitrile released). In addition, JH III had a significant effect on the external colouration and absorbance ratios of the haemolymph pigments. It is concluded that the effects of exogenous JH III on gregarious locusts represent a shift …

Go to article

Effects Of Tsetse Dna Virus Infection On The Survival Of A Host Fly,Glossina Morsitans Centralis(Diptera; Glossinidae), Rosemary C. Sang, Walter G.Z.O. Jura, Leonard H. Otieno, Peter M. Tukei, Richard W. Mwangi May 1997

Effects Of Tsetse Dna Virus Infection On The Survival Of A Host Fly,Glossina Morsitans Centralis(Diptera; Glossinidae), Rosemary C. Sang, Walter G.Z.O. Jura, Leonard H. Otieno, Peter M. Tukei, Richard W. Mwangi

All Peer-Reviewed Publications

Freshly deposited third instarGlossina morsitans centralislarvae were infected with the tsetse DNA virus by microinjection. At emergence comparative observations were made on longevity and feeding behavior of infected and control flies. Gut tissues from the control and virus-infected flies were fixed and processed for light and electron microscopy. The longevity of infected flies was significantly reduced compared to that of the controls (P<0.05). The main mortality factors in the virus-infected flies with severe lesions in the salivary glands were starvation due to failure to feed and clotting of blood in and/or rupture of the crop. Rupture of the midgut also caused some mortalities. Infected flies probed significantly more times during feeding to repletion (P<0.05) and took significantly longer to feed compared to the control flies (P<0.05). Infected flies which fed took significantly less blood compared to the controls (P<0.05). Histological studies revealed pathological changes in the epithelial cells of the anterior midgut secretory midgut and the posterior midgut. There was severe disintegration of the membranous organelles, especially the mitochondria and rough endoplasmic reticulum, leading to extensive vacuolation in such epithelial cells. No viral particles were observed in the secretory and posterior midgut. Virions were observed in the anterior midgut lumen and occasional particles were seen invading the epithelial cells in this area of the midgut, especially in heavily infected flies. © 1997 Academic Press.

Go to article

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

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

All Peer-Reviewed Publications

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

Go to article

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

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

All Peer-Reviewed Publications

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

Go to article

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

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

All Peer-Reviewed Publications

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

Go to article

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

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

All Peer-Reviewed Publications

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

Go to article

Combining Ability Of Resistance To The Sorghum Shootfly, Atherigona Soccata And Stemborer Chilo Partellus In Grain Sorghum, Sorghum Bicolor, A. A. Elbadawi, A. M. Nour, R. S. Pathak Jan 1997

Combining Ability Of Resistance To The Sorghum Shootfly, Atherigona Soccata And Stemborer Chilo Partellus In Grain Sorghum, Sorghum Bicolor, A. A. Elbadawi, A. M. Nour, R. S. Pathak

All Peer-Reviewed Publications

Combining ability of resistance to the sorghum shootfly, Atherigona soccata and spotted stemborer, Chilo partellus in grain sorghum was analysed on a seven-parents diallel in a field trial at the ICIPE Mbita Point Field Station, western Kenya during the 1990 long rainy season. Lines with best performance for each of the four measured resistance parameters were also found to be the best general combiners. Resistance to leaf damage and number of holes/metre were controlled by additive gene effects whereas resistance to deadheart and stem tunnelling were controlled by additive and non-additive gene effects. Parents IS-1044, IS-12308 and IS-2269 with their …

Go to article

Les Inhibiteurs Des Facteurs Humoraux Chez Les Criquets Migrateurs, Schistocerca Gregaria Et Locusta Migratoria: Perspectives D'Utilisation Dans La Lutte Biologique, D. Dakouo, S. Essuman, S. K. Raina, M. Bréhélin, Latifa Drif Jan 1997

Les Inhibiteurs Des Facteurs Humoraux Chez Les Criquets Migrateurs, Schistocerca Gregaria Et Locusta Migratoria: Perspectives D'Utilisation Dans La Lutte Biologique, D. Dakouo, S. Essuman, S. K. Raina, M. Bréhélin, Latifa Drif

All Peer-Reviewed Publications

Haemolymph from the locusts Schistocercagregaria and Locustamigratoria contains humoral factors such as lectin and phenoloxidase system. In vitro studies demonstrated that phenoloxidase system can be activated by LPS, laminarin, Malamoeba locustae cysts, trypsin and methanol. Haemolymph showed agglutination activity for mammalian erythrocytes and protozoa (M. locustae, Leishmania major and Trypanosoma brucei). A purified lectin was isolated fromhaemolymphby affinity chromatography. Analysis by SDS-PAGE gave a single band at 80 kD while on native PAGE, it gave a single band at 650 kD. Inhibitors of the two humoral factors were investigated. Lectin activity was inhibited by nitrophenyl a D-galactopyranoside in both cases …

Go to article

First Prev Next Last