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E. S. Krafsur - One of the best experts on this subject based on the ideXlab platform.
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Phylogeography and genealogy of the tsetse fly Glossina pallidipes (Diptera: Glossinidae)
International Journal of Tropical Insect Science, 2016Co-Authors: E. S. Krafsur, J. G. Marquez, J. O. OumaAbstract:Glossina pallidipes , a widely but discontinuously distributed African savanna species, is one of the economically important tsetse flies because it is a vector of trypanosomiasis, a lethal disease of cattle and other domestic animals. DNA sequences of ribosomal ( r16S2 , 249bp) and cytochrome oxidase I ( COI , 421 bp) concatenated mitochondrial genes were analysed in 23 geographically diverse samples of G. pallidipes from Ethiopia, Kenya, Tanzania, Zambia and Zimbabwe. Among 873 flies, we detected 181 composite haplotypes and found that their spatial diversities and frequency distributions were heterogeneous. Haplotype and nucleotide diversities were greatest in Ethiopia and least in southern Africa. We observed little haplotype and nucleotide diversity among regions, and detected severely limited maternal gene flow among the sampled populations (Φ_ST = 0.42). Tests for demographic stability and analysis of mismatch distributions revealed regionally contrasting demographic histories. The Ethiopian populations were phylogenetically the oldest and genetically the most diverse, and exhibited successive waves of contraction and expansion. The southern African populations were phylogenetically the youngest and genetically the least diverse, and showed only a single, recent expansion. Likely ecological correlates of historical tsetse fly demography include population suppression trials in East Africa and recurring rinderpest epizootics in southern Africa, beginning in the late nineteenth century that reduced host mammalian populations.
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macrogeographic population structure of the tsetse fly glossina pallidipes diptera Glossinidae
Bulletin of Entomological Research, 2005Co-Authors: J. O. Ouma, J. G. Marquez, E. S. KrafsurAbstract:Tsetse flies are confined to sub-Saharan Africa where they occupy discontinuous habitats. In anticipation of area-wide control programmes, estimates of gene flow among tsetse populations are necessary. Genetic diversities were partitioned at eight microsatellite loci and five mitochondrial loci in 21 Glossina pallidipes Austin populations. At microsatellite loci, Nei’s unbiased gene diversity averaged over loci was 0.659 and the total number of alleles was 214, only four of which were shared among all populations. The mean number of alleles per locus was 26.8. Random mating was observed within but not among populations (fixation index FST = 0.18) and 81% of the genetic variance was within populations. Thirty-nine mitochondrial variants were detected. Mitochondrial diversities in populations varied from 0 to 0.85 and averaged 0.42, and FST = 0.51. High levels of genetic differentiation were characteristic, extending even to subpopulations separated by tens and hundreds of kilometres, and indicating low rates of gene flow.
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mitochondrial diversity analysis of glossina palpalis gambiensis from mali and senegal
Medical and Veterinary Entomology, 2004Co-Authors: J. G. Marquez, Marc J. B. Vreysen, A S Robinson, S Bado, E. S. KrafsurAbstract:West African riverine tsetse populations of Glossina palpalis gambiensis Vanderplank (Diptera: Glossinidae) were investigated for gene flow, inferred from mitochondrial diversity in samples of 69 flies from Senegal and 303 flies from three river drainages in Mali. Four polymorphic mitochondrial loci were scored. Mean haplotype diversities were 0.30 in Mali, 0 in Senegal and 0.18 over both Mali and Senegal. These diversities estimate the probabilities that two randomly chosen tsetse have different haplotypes. Substantial rates of gene flow were detected among flies sampled along tributaries belonging to the river basins of the Senegal, Niger, and Bani in Mali. There was virtually no gene flow between tsetse in Senegal and Mali. No seasonal effects on gene flow were detected. The implications of these preliminary findings for the implementation of area-wide integrated pest management (AW-IPM) programmes against riverine tsetse in West Africa are discussed.
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characterization of microsatellite markers in the tsetse fly glossina pallidipes diptera Glossinidae
Molecular Ecology Notes, 2003Co-Authors: J. O. Ouma, M A Cummings, K C Jones, E. S. KrafsurAbstract:Glossina pallidipes is a vector of African trypanosomiasis. Here we characterize eight new polymorphic microsatellite loci in 288 G. pallidipes sampled from 12 Kenya populations. The number of alleles per locus ranged from four to 36 with a mean of 20.5 +/- 10.1. Expected single locus heterozygosities varied from 0.044 to 0.829. Heterozygosity averaged 0.616 +/- 0.246. No linkage disequilibrium was found. We also report results in eight other tsetse species estimated by using the primers developed in G. pallidipes. The primers worked best in G. swynnertoni and G. austeni and worst in G. m. morsitans and G. m. submorsitans.
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microsatellite diversities and gene flow in the tsetse fly glossina morsitans s l
Medical and Veterinary Entomology, 2002Co-Authors: E. S. Krafsur, M. A. EndsleyAbstract:Abstract Tsetse flies occupy discontinuous habitats and gene flow among them needs to be investigated in anticipation of area-wide control programs. Genetic diversities were estimated at six microsatellite loci in seven Glossina morsitans submorsitans Newstead (Diptera: Glossinidae) populations and five microsatellite loci in six G. m. morsitans Westwood populations. Nei's unbiased diversities were 0.808 and 76 alleles in G. m. submorsitans and 0.727 and 55 alleles in G. m. morsitans. Diversities were less in three laboratory cultures. Matings were random within populations. Populations were highly differentiated genetically. Populations were strongly subdivided, as indicated by fixation indices (FST) of 0.18 in G. m. morsitans and 0.17 in G. m. submorsitans. 35% of the genetic variance in G. m. submorsitans was attributed to differences between populations from The Gambia and Ethiopia. All available genetic evidence suggests that genetic drift is much greater than gene flow among G. morsitans s.l. populations.
Stephen J. Torr - One of the best experts on this subject based on the ideXlab platform.
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efficacy of electrocuting devices to catch tsetse flies Glossinidae and other diptera
PLOS Neglected Tropical Diseases, 2015Co-Authors: G A Vale, Andrew Chamisa, John W Hargrove, Alan N Cullis, Stephen J. TorrAbstract:CITATION: Vale, G.A., Hargrove, J.W., Cullis, N.A, Chamisa, A. & Torr, S.J. 2015. Efficacy of electrocuting devices to catch tsetse flies (Glossinidae) and other diptera. PLoS Neglected Tropical Diseases, 9(10):e0004169, doi:10.1371/ journal.pntd.0004169.
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Responses of tsetse flies, Glossina morsitans morsitans and Glossina pallidipes, to baits of various size
Medical and veterinary entomology, 2011Co-Authors: Stephen J. Torr, Michael J Lehane, Andrew Chamisa, Glyn A. Vale, Jenny M. LindhAbstract:Recent studies of Palpalis group tsetse [Glossina fuscipes fuscipes (Diptera: Glossinidae) in Kenya] suggest that small (0.25 × 0.25 m) insecticide-treated targets will be more cost-effective than the larger (≥1.0 × 1.0 m) designs currently used to control tsetse. Studies were undertaken in Zimbabwe to assess whether small targets are also more cost-effective for the Morsitans group tsetse, Glossina morsitans morsitans and Glossina pallidipes. Numbers of tsetse contacting targets of 0.25 × 0.25 m or 1.0 × 1.0 m, respectively, were estimated using arrangements of electrocuting grids which killed or stunned tsetse as they contacted the target. Catches of G. pallidipes and G. m. morsitans at small (0.25 × 0.25 m) targets were, respectively, ∼1% and ∼6% of catches at large (1.0 × 1.0 m) targets. Hence, the tsetse killed per unit area of target was greater for the larger than the smaller target, suggesting that small targets are not cost-effective for use against Morsitans group species. The results suggest that there is a fundamental difference in the host-orientated behaviour of Morsitans and Palpalis group tsetse and that the former are more responsive to host odours, whereas the latter seem highly responsive to visual stimuli.
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insecticide treated cattle against tsetse diptera Glossinidae what governs success
Bulletin of Entomological Research, 2003Co-Authors: John W Hargrove, Stephen J. Torr, H M KindnessAbstract:The distributions of insecticide-treated cattle from sites in Tanzania and Zimbabwe were assessed from interviews with livestock owners, analysis of secondary livestock data and mapping technologies. The time-course of tsetse control operations at these sites were then simulated using a mathematical model that assumed diffusive movement and logistic growth in fly populations. A simulation of a tsetse control operation in Mudzi district, north-east Zimbabwe, was in accord with observations that the use of insecticide-treated cattle was unable to prevent substantial re-invasion of tsetse from Mozambique, consequent on the patchy distribution of cattle. The simulation was also consistent with the observed efficacy of a 10-km wide barrier of insecticide-treated targets deployed evenly at 4 km -2 . Simulation of a control operation on Mkwaja Ranch in Tanzania was in accord with the observation that the use of insecticide-treated cattle reduced the tsetse population on the ranch by c. 90%. Insecticide-treated cattle were used to better effect in the Kagera Region of Tanzania. Simulation of this operation predicts that the deployment of 35,000 treated cattle in the area would result in > 99% control of the tsetse population, consistent with the observed decline, by 1–2 orders of magnitude, in cases of trypanosomiasis in the region. The greater success of the Kagera operation was due to the size and shape of the treated area and, particularly, to the restriction of re-invasion to 20% of the perimeter, compared with > 80% on Mkwaja. Simulation was used to assess how tsetse control could have been improved at Mkwaja. The results suggest that splitting herds into smaller, more numerous, units could have achieved some improvement but, in general, the disease problem would not have been solved by the use of insecticide-treated cattle alone. Only by deploying odourbaited targets in ungrazed areas, or in a 1–3-km barrier around the ranch, could substantially better control (99–99.9%) have been achieved. Sensitivity analyses of the Mkwaja simulation showed that the general conclusions were robust to assumptions regarding cattle distribution and the rates of fly movement and growth. Properly managed and appropriately applied insecticide-treated baits are powerful weapons for tsetse control but should not be used without regard to potential levels of re-invasion, consequent largely on considerations of the size and shape of the treatment area and the density and distribution of the baits.
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application of dna markers to identify the individual specific hosts of tsetse feeding on cattle
Medical and Veterinary Entomology, 2001Co-Authors: Stephen J. Torr, T.n.c. Mangwiro, Paul J Wilson, S Schofield, S Akber, Brad WhiteAbstract:Primer sets for five different ungulate loci were used to obtain individual microsatellite DNA profiles for 29 Mashona cattle from a herd in Zimbabwe. There were 3-13 alleles for each locus and, using the entire suite of five loci, each animal within the herd, including closely related individuals, could be unequivocally distinguished. Wild-caught Glossina pallidipes Austen (Diptera: Glossinidae) were fed on specific cattle and the bloodmeal was profiled 0.5-72 h after feeding. The individual specific sources of the bloodmeals, including mixe meals produced by allowing tsetse to feed on two different cattle, were reliabl identified up to 24 h after feeding. The technique was used in field studies of hos selection by G. pallidipes and G. morsitans morsitans Westwood (Diptera Glossinidae) attracted to pairs of cattle. When the pair comprised an adult and a calf, 100% of meals were from the adult. For some pairs of adult cattle, tsetse were biased significantly towards feeding on one animal, whereas for other pairs there was no such bias. In general, feeding was greater on the animal known to have lower rate of host defensive behaviour. Results suggest that relatively slight differences in the inherent defensive behaviour of cattle produce large difference in host-specific feeding rates when the hosts are adjacent. For flies attracted to pair of cattle, < 2% contained blood from both hosts. The DNA profiling technique will be useful in studying the epidemiology of vector-borne diseases of livestock.
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methods for dispensing odour attractants for tsetse flies diptera Glossinidae
Bulletin of Entomological Research, 1997Co-Authors: Stephen J. Torr, David Hall, R J Phelps, G A ValeAbstract:Methods for dispensing tsetse attractants using sealed polyethylene sachets and bottles were studied in the laboratory and field. 1-Octen-3-ol (octenol), 4-methylphenol and 3-n-propylphenol were dispensed singly or as blends from sachets 25–200 cm2 in surface area and with a wall thickness of 0.06–0.32 mm; butanone was dispensed from polyethylene bottles. The release rates of attractants, assessed gravimetrically or by GC analysis of volatiles released, were independent of the amount present. The rates were related directly to surface area, inversely related to wall thickness and increased exponentially with temperature. With blends of the attractants, the release rates of the two phenols were directly proportional to the concentration present, but that of octenol showed an exponential dependence. A similar exponential effect was seen with blends of the attractants and an involatile diluent. For mixtures of chemicals, the ratio of the released components was not affected significantly by temperature, sachet size or wall thickness. Release rates from polyethylene sachets and bottles in the field varied 100-fold according to temperature differences related to the time of day, season, and degree of insolation. Day-degree models to predict the losses of attractants from a polyethylene sachet in shade or in full sunlight were highly correlated (r2 = 0.84 and 0.81 respectively) with observed losses. The practical implications of these findings are discussed.
Serap Aksoy - One of the best experts on this subject based on the ideXlab platform.
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genetic diversity of glossina fuscipes fuscipes along the shores of lake victoria in tanzania and kenya implications for management
Parasites & Vectors, 2017Co-Authors: Oliver Manangwa, Serap Aksoy, Gamba Nkwengulila, Johnson O Ouma, Furaha Mramba, Imna Malele, Kirsten Dion, Mark Sistrom, Farrah Khan, Adalgisa CacconeAbstract:Background Tsetse flies (Diptera: Glossinidae) are sole vectors for trypanosomiasis, which affect human health and livestock productivity in Africa. Little is known about the genetic diversity of Glossina fuscipes fuscipes, which is an important species in Tanzania and Kenya. The main objective of the study was to provide baseline data to determine the genetic variability and divergence of G. f. fuscipes in the Lake Victoria basin of Tanzania and Kenya in order to guide future vector control efforts in the region.
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The Spermatophore in Glossina morsitans morsitans: Insights into Male Contributions to Reproduction
Scientific Reports, 2016Co-Authors: Francesca Scolari, Veronika Michalkova, Emre Aksoy, Adly M. M. Abd-alla, Anna R. Malacrida, Joshua B Benoit, Peter Takac, Serap Aksoy, Geoffrey M. AttardoAbstract:Male Seminal Fluid Proteins (SFPs) transferred during copulation modulate female reproductive physiology and behavior, impacting sperm storage/use, ovulation, oviposition and remating receptivity. These capabilities make them ideal targets for developing novel methods of insect disease vector control. Little is known about the nature of SFPs in the viviparous tsetse flies (Diptera: Glossinidae), vectors of Human and Animal African trypanosomiasis. In tsetse, male ejaculate is assembled into a capsule-like spermatophore structure visible post-copulation in the female uterus. We applied high-throughput approaches to uncover the composition of the spermatophore in Glossina morsitans morsitans . We found that both male accessory glands and testes contribute to its formation. The male accessory glands produce a small number of abundant novel proteins with yet unknown functions, in addition to enzyme inhibitors and peptidase regulators. The testes contribute sperm in addition to a diverse array of less abundant proteins associated with binding, oxidoreductase/transferase activities, cytoskeletal and lipid/carbohydrate transporter functions. Proteins encoded by female-biased genes are also found in the spermatophore. About half of the proteins display sequence conservation relative to other Diptera and low similarity to SFPs from other studied species, possibly reflecting both their fast evolutionary pace and the divergent nature of tsetse’s viviparous biology.
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refractoriness in tsetse flies diptera Glossinidae may be a matter of timing
Journal of Medical Entomology, 2007Co-Authors: Dana Nayduch, Serap AksoyAbstract:Tsetse flies (Diptera: Glossinidae: Glossina spp.) are vectors for African trypanosomiasis, a devastating disease that kills both people and animals in sub-Saharan Africa. Trypanosomes ingested with an infected bloodmeal reside within the gut of tsetse and eventually move to the salivary glands where they become transmissible during blood feeding. Although tsetses are efficient vectors for disease transmission, infection prevalence in the field is surprisingly low, a trait referred to as refractoriness. Refractoriness is relatively more pronounced in palpalis subgroup flies, although certain species within the susceptible morsitans species complex are also highly refractory, such as Glossina pallidipes Austen. We examined the role of the humoral immune response in refractoriness to infection by comparing the expression of the antimicrobial peptide gene attacin across three species with varied vector competence. Gene expression was measured both temporally (time after feeding and fly age) and spatially (tissue specificity). Although microbial immune challenge induces attacin expression in all three species, "refractory" fly species showed an uninduced, baseline level of systemic (fat body) attacin, whereas the "susceptible" flies did not. In addition, refractory species had a higher level of attacin expression in the proventriculus and midgut. We also found that blood feeding alone up-regulated attacin expression in refractory species but not in the susceptible species. Finally, reverse genetics showed that repression of attacin by double-stranded RNA-mediated RNA interference increased susceptibility to trypanosome infection in G. pallidipes. The role of early, uninduced attacin expression, and its role in relative refractoriness in tsetse, is discussed.
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Molecular characterization of iron binding proteins from Glossina morsitans morsitans (Diptera: Glossinidae)
Insect Biochemistry and Molecular Biology, 2006Co-Authors: Patricia M. Strickler-dinglasan, Geoffrey M. Attardo, Serap AksoyAbstract:Abstract The regulation of iron is critical for maintaining homeostasis in the tsetse fly (Diptera: Glossinidae), in which both adult sexes are strict blood feeders. We have characterized the cDNAs for two putative iron-binding proteins (IBPs) involved in transport and storage; transferrin ( GmmTsf1 ) and ferritin from Glossina morsitans morsitans. GmmTsf1 transcripts are detected in the female fat body and in adult reproductive tissues, and only in the adult developmental stage in a bloodmeal independent manner. In contrast, the ferritin heavy chain ( GmmFer1HCH ) and light chain ( GmmFer2LCH ) transcripts are expressed ubiquitously, suggesting a more general role for these proteins in iron transport and storage. Protein domain predictions for each IBP suggest both the conservation and loss of several motifs present in their vertebrate homologues. In concert with many other described insect transferrins (Tfs), putative secreted GmmTsf1 maintains 3 of the 5 residues necessary for iron-binding in the N-terminal lobe, but exhibits a loss of this iron-binding ability in the C-terminal lobe as well as a loss of large sequence blocks. Both putative GmmFer1HCH and GmmFer2LCH proteins have signal peptides, similar to other insect ferritins. GmmFer2LCH has lost the 5′UTR iron-responsive element (IRE) and, thus, translation is no longer regulated by cellular iron levels. On the other hand, GmmFer1HCH maintains both the conserved ferroxidase center and the 5′UTR IRE; however, transcript variants suggest a more extensive regulatory mechanism for this subunit.
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microsatellite polymorphism in tsetse flies diptera Glossinidae
Journal of Medical Entomology, 2001Co-Authors: Coralia Luna, Serap Aksoy, Mariangela Bonizzoni, Quiying Cheng, Alan S Robinson, Liangbiao ZhengAbstract:In sub-Saharan Africa, tsetse flies are the vectors of trypanosomes, the causative agents of sleeping sickness in humans and nagana in animals. Certain wild populations of the palpalis group exhibit intraspecific variation and are suspect of manifest differences in vectorial capacity. The current study reports the identification of 13 polymorphic microsatellite loci from Glossina palpalis palpalis Robinean-Desvoidy. The majority of these markers amplify corresponding loci from the related species G. p. gambiensis Vanderplank, G. f. fuscipes Newstead, and G. tachinoides Westwood. Only seven of 13 loci were amplified from G. austeni Newstead. Genetic variability was estimated in one field population of G. p. gambiensis. These results confirmed that microsatellite markers may be used to examine the subpopulation structure of tsetse flies.
G A Vale - One of the best experts on this subject based on the ideXlab platform.
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efficacy of electrocuting devices to catch tsetse flies Glossinidae and other diptera
PLOS Neglected Tropical Diseases, 2015Co-Authors: G A Vale, Andrew Chamisa, John W Hargrove, Alan N Cullis, Stephen J. TorrAbstract:CITATION: Vale, G.A., Hargrove, J.W., Cullis, N.A, Chamisa, A. & Torr, S.J. 2015. Efficacy of electrocuting devices to catch tsetse flies (Glossinidae) and other diptera. PLoS Neglected Tropical Diseases, 9(10):e0004169, doi:10.1371/ journal.pntd.0004169.
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insecticide treated cattle for controlling tsetse flies diptera Glossinidae some questions answered many posed
Bulletin of Entomological Research, 1999Co-Authors: G A Vale, G Mutika, D F LovemoreAbstract:Bioassays in Zimbabwe with wild-caught Glossina pallidipes Austen and G. morsitans morsitans Westwood showed that formulations of deltamethrin (Decatix, SpotOn and an experimental variant of SpotOn), alphacypermethrin (Renegade) and cyfluthrin (Cylence) applied to oxen at the manufacturers’ recommended doses gave knockdowns above 50% for 5‐24 days in hot months and 24‐55 days at cooler seasons. Within these periods, the average knockdowns were 77‐86% with deltamethrin, 74% with alphacypermethrin and 59% with cyfluthrin. None of the insecticides affected the numbers of tsetse attracted to oxen from a distance, the proportion of tsetse that engorged, and the alighting responses on cloth screens. In the hot season most tsetse engorged on the belly. At other times the front legs were preferred, especially in the wet season and for a few months after. Chemical assays indicated that insecticide persisted at greatest concentration on the backs of oxen and least on the legs. Modelling the experimental data suggested that 4‐21 annual applications of insecticide in areas >1000 km 2 would give good control at least 10 km from the invasion source if the treated cattle contributed at least 50% of tsetse diet. No treatment regime under any diet conditions would give good control near an invasion front. Insecticide at concentrations up to 0.15 ppm occurred in dung from treated oxen for up 12 days post-treatment. Dead beetles occurred in and near fresh dung.
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methods for dispensing odour attractants for tsetse flies diptera Glossinidae
Bulletin of Entomological Research, 1997Co-Authors: Stephen J. Torr, David Hall, R J Phelps, G A ValeAbstract:Methods for dispensing tsetse attractants using sealed polyethylene sachets and bottles were studied in the laboratory and field. 1-Octen-3-ol (octenol), 4-methylphenol and 3-n-propylphenol were dispensed singly or as blends from sachets 25–200 cm2 in surface area and with a wall thickness of 0.06–0.32 mm; butanone was dispensed from polyethylene bottles. The release rates of attractants, assessed gravimetrically or by GC analysis of volatiles released, were independent of the amount present. The rates were related directly to surface area, inversely related to wall thickness and increased exponentially with temperature. With blends of the attractants, the release rates of the two phenols were directly proportional to the concentration present, but that of octenol showed an exponential dependence. A similar exponential effect was seen with blends of the attractants and an involatile diluent. For mixtures of chemicals, the ratio of the released components was not affected significantly by temperature, sachet size or wall thickness. Release rates from polyethylene sachets and bottles in the field varied 100-fold according to temperature differences related to the time of day, season, and degree of insolation. Day-degree models to predict the losses of attractants from a polyethylene sachet in shade or in full sunlight were highly correlated (r2 = 0.84 and 0.81 respectively) with observed losses. The practical implications of these findings are discussed.
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development of baits for tsetse flies diptera Glossinidae in zimbabwe
Journal of Medical Entomology, 1993Co-Authors: G A ValeAbstract:Analysis of host-oriented behavior of tsetse flies, Glossina morsitans morsitans Westw. and G. pallidipes Austen, led to a 10- to 1,000-fold improvement in the cost effectiveness of baits for surveys and control. Baits now are used widely to replace air and ground broadcasting of insecticides. Principles of behavioral analysis are discussed, with emphasis on the need to: confirm that the measurements made are the measurements required; assess the probability of flies executing single specific actions in response to each component of the overall stimulus from baits; count not only the flies that do one thing, but also the number that do the alternative(s); and use objective sampling devices of measured efficiency. The relevance to research with other flies is considered. The need for new tools to study continuously the field behavior of individual flies is stressed.
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visual responses of tsetse flies diptera Glossinidae to odour baited targets
Bulletin of Entomological Research, 1993Co-Authors: G A ValeAbstract:Field studies in Zimbabwe showed how targets 1 m tall and 25–400 cm wide, composed of vertical panels of visual material and net and baited with odours of acetone, 1-octen-3-ol, and phenols, could be refined for controlling Glossina morsitans morsitans Westwood and G. pallidipes Austen. Attraction from a distance was not affected by swivelling movement but improved several-fold as the width of visual panels increased from 25 to 200 cm. Blue or blue/black targets were about as effective as black for G. m. morsitans but slightly more effective for G. pallidipes. Fine and coarse net was unattractive at long range but the flies avoided coarse net when close. The percentage of tsetse alighting on visual panels before flying round increased up to several times when the panels were widened, and when non-shiny black replaced blue or shiny black, but the percentage of flies alighting before departure was not much affected expect by panel width, being near 0% at 25 cm and 85% at 2 m. Most tsetse alighted first near the centre of targets, especially where black contrasted with nearby blue. Studies of various fabrics and paints and of restricted deposition of insecticide suggested several disposable targets that could have the costs of materials and insecticide, with efficacy preserved for G. m. morsitans and increased by up to 50% for G. pallidipes.
Jérémy Bouyer - One of the best experts on this subject based on the ideXlab platform.
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evaluation of the relative roles of the tabanidae and Glossinidae in the transmission of trypanosomosis in drug resistance hotspots in mozambique
Parasites & Vectors, 2020Co-Authors: Fernando Chanisso Mulandane, Jérémy Bouyer, Jan Van Den Abbeele, Louwtjie P Snyman, Denise R A Brito, Jose Fafetine, Marinda C Oosthuizen, V DelespauxAbstract:Tsetse flies (Diptera: Glossinidae) and tabanids (Diptera: Tabanidae) are haematophagous insects of medical and veterinary importance due to their respective role in the biological and mechanical transmission of trypanosomes. Few studies on the distribution and relative abundance of both families have been conducted in Mozambique since the country’s independence. Despite Nicoadala, Mozambique, being a multiple trypanocidal drug resistance hotspot no information regarding the distribution, seasonality or infection rates of fly-vectors are available. This is, however, crucial to understanding the epidemiology of trypanosomosis and to refine vector management. For 365 days, 55 traps (20 NGU traps, 20 horizontal traps and 15 Epsilon traps) were deployed in three grazing areas of Nicoadala District: Namitangurine (25 traps); Zalala (15 traps); and Botao (15 traps). Flies were collected weekly and preserved in 70% ethanol. Identification using morphological keys was followed by molecular confirmation using cytochrome c oxidase subunit 1 gene. Trap efficiency, species distribution and seasonal abundance were also assessed. To determine trypanosome infection rates, DNA was extracted from the captured flies, and submitted to 18S PCR-RFLP screening for the detection of Trypanosoma. In total, 4379 tabanids (of 10 species) and 24 tsetse flies (of 3 species), were caught. NGU traps were more effective in capturing both the Tabanidae and Glossinidae. Higher abundance and species diversity were observed in Namitangurine followed by Zalala and Botao. Tabanid abundance was approximately double during the rainy season compared to the dry season. Trypanosoma congolense and T. theileri were detected in the flies with overall infection rates of 75% for tsetse flies and 13% for tabanids. Atylotus agrestis had the highest infection rate of the tabanid species. The only pathogenic trypanosome detected was T. congolense. Despite the low numbers of tsetse flies captured, it can be assumed that they are still the cyclical vectors of trypanosomosis in the area. However, the high numbers of tabanids captured, associated to their demonstrated capacity of transmitting trypanosomes mechanically, suggest an important role in the epidemiology of trypanosomosis in the Nicoadala district. These results on the composition of tsetse and tabanid populations as well as the observed infection rates, should be considered when defining strategies to control the disease.
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Larviposition site selection mediated by volatile semiochemicals in Glossina palpalis gambiensis
Ecological Entomology, 2020Co-Authors: Geoffrey Gimonneau, Romaric Ouedraogo, Bruno Buatois, Laurent Dormont, Olivier Roux, Philippe Solano, Jean Baptiste Rayaisse, Ernest Salou, Jérémy BouyerAbstract:1. Tsetse flies (Diptera: Glossinidae) are K‐strategist species and deposit a single larva at 10‐day intervals in specific sites. As larviposition site selection strongly impacts reproductive success, the selection of larviposition sites is unlikely to be random and will be subject to strong selective processes, probably mediated by specific cues. 2. This study was designed to assess the existence of an aggregation effect in the palpalis group and to test its potential chemical nature (contact or volatile compounds). The larviposition site selection of Glossina palpalis gambiensis was studied according to the presence of conspecific and heterospecific larvae (morsitans group) buried in substrates. Three sets of experiments were performed with either individual or grouped gravid females and with or without physical access to the substrate. 3. In individual larviposition experiments, females were more likely to select trays with buried larvae than unconditioned sand (63.2% and 36.8%, respectively; P
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RESEARCH Open Access Impact of habitat fragmentation on tsetse populations and trypanosomosis risk in
2016Co-Authors: Cornelius Mweempwa, Jérémy Bouyer, Tanguy Marcotty, Claudia De Pus, Barend Louis Penzhorn, Ahmadou Hamady Dicko, Reginald De DekenAbstract:Background: Fragmentation of tsetse habitat in eastern Zambia is largely due to encroachments by subsistence farmers into new areas in search of new agricultural land. The impact of habitat fragmentation on tsetse populations is not clearly understood. This study was aimed at establishing the impact of habitat fragmentation on physiological and demographic parameters of tsetse flies in order to enhance the understanding of the relationship between fragmentation and African animal trypanosomosis (AAT) risk. Methods: A longitudinal study was conducted to establish the age structure, abundance, proportion of females and trypanosome infection rate of Glossina morsitans morsitans Westwood (Diptera: Glossinidae) in areas of varying degrees of habitat fragmentation in Eastern Zambia. Black screen fly rounds were used to sample tsetse populations monthly for 1 year. Logistic regression was used to analyse age, proportion of females and infection rate data. Results: Flies got significantly older as fragmentation increased (p < 0.004). The proportion of old flies, i.e. above ovarian category four, increased significantly (P < 0.001) from 25.9 % (CI 21.4–31.1) at the least fragmented site (Lusandwa) to 74.2 % (CI 56.8–86.3) at the highly fragmented site (Chisulo). In the most fragmented area (Kasamanda), tsetse flies had almost disappeared. In the highly fragmented area a significantly higher trypanosom
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mating performance of glossina palpalis gambiensis strains from burkina faso mali and senegal
Entomologia Experimentalis Et Applicata, 2013Co-Authors: Gratian N Mutika, Andrew G Parker, Jérémy Bouyer, Momar Talla Seck, Baba Sall, Idrissa Kabore, Marc J. B. VreysenAbstract:The mating performance of Glossina palpalis gambiensis Vanderplank (Diptera: Glossinidae) mass-reared in Burkina Faso (BKF strain) was compared with that of target populations originating from the Bamako peri-urban area of the Niger River Basin, Mali (MLI strain) and the Niayes area, Senegal (SEN strain). The tests were carried out using a field cage either set up outdoors in Burkina Faso or inside the laboratory in Austria. The target population strains (MLI and SEN) were a few generations from the wild whereas the laboratory-reared flies (BKF) were adapted to laboratory rearing over many generations. The laboratory-reared BKF strain significantly out-competed the MLI strain in the mating tests, but showed close to equal competitiveness with the SEN strain. At least one-third of possible matings occurred during each observation period. The females from the two target populations readily mated with males from the BKF strain. The selected mating parameters and behaviour in the cage showed that there was mating compatibility between the strains and this absence of obvious mating barriers indicates the potential of using BKF strain males in programmes that have a sterile insect technique (SIT) component targeting the two G. p. gambiensis populations of Mali and Senegal. (Resume d'auteur)
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spatio temporal modelling of glossina palpalis gambiensis and glossina tachinoides apparent densities in fragmented ecosystems of burkina faso
Ecography, 2010Co-Authors: Luigi Sedda, Jérémy Bouyer, Laure Guerrini, Naferima Kone, David J RogersAbstract:Here we propose two novel approaches to space-time analysis derived from space-time geostatistics in a kriging framework. The approaches were developed through analysis of a dataset recording the Apparent Density of Glossina palpalis gambiensis and Glossina tachinoides (Diptera: Glossinidae) in three riparian sites in Burkina Faso over 15 months between 2006 and 2007. This site is fragmented due to human activity in the area. The first approach, Space Time Ordinary Kriging, does not consider the effect of fragmentation. It is used as a benchmark to test the increased explanatory power of the second method, which does account for fragmentation. The second method, Regression Space Time Simple Kriging, is a distinct improvement over the first approach because it allows for a spatial trend in the mean trap catch; this trend is related to, and later predicted from, environmental co-variates. The results indicate the presence of space and time effects on tsetse distribution, dependent on the size of the habitat fragmentation patches. These effects occur at relatively small geographic scales within a season. Whilst such variation has long been suspected, the new methods presented here are able to quantify this variation precisely, so that seasonal and spatial comparisons can now be made both within and between species.