Spelling suggestions: "subject:"tsetsefliege"" "subject:"betterflies""
11 |
An investigation of the utility of remotely sensed meterological satellite data for predicting the distribution and abundance of the tsetse fly (Diptera: Glossinidae)Hay, Simon Iain January 1996 (has links)
This thesis investigates the potential contribution of data from the Advance Very High Resolution Radiometer (AVHRR) on-board the National Oceanic and Atmospheric Administrations (NOAA) polar-orbiting meteorological satellites and data from the High Resolution Radiometer (HRR) on-board the Meteosat geostationary meteorological satellites for predicting the distribution and abundance of the tsetse fly (Diptera: Glossinidae) in Africa. The images were processed to produce a range of monthly land surface temperature, atmospheric moisture and rainfall indices for the period 1988 to 1990. The performance of these indices, derived from several different methods, was tested using meteorological records collected during these years at stations across continental Africa and the most accurate used to form a refined dataset for subsequent analysis. The time-series of these land surface temperature, atmospheric moisture and rainfall indices and a range of Spectral Vegetation Indices (SVI) were subject to temporal Fourier analysis to parameterise the seasonal variation in these variables. These data, in combination with elevation information from a digital elevation model (DEM) were used to predict the land-cover of Nigeria determined independently by an aerial survey in 1990. The Normalised Difference Vegetation Index (NDVI) performed best and so was used in combination with the satellite proxy meteorological and DEM data to predict the distribution and abundance of eight tsetse fly species in Cote d'lvoire and Burkina Faso, West Africa. The results are discussed in relation to the ecology of the different tsetse species. Conclusions are then drawn on the potential of such meteorological satellite data for remote tsetse fly population surveillance and, in the wider context, to the study and control of arthropod vectors of disease.
|
12 |
Proteomic and immunochemical study of the tsetse fly 'Glossina morsitans morsitans' midgut and salivary glandHaddow, Jody Daniel. 10 April 2008 (has links)
No description available.
|
13 |
Variability among individuals and populations : implications for arthropod physiologyTerblanche, Jonathan Steed 04 1900 (has links)
Dissertation (PhD)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Within arthropods, inter-individual and inter-population variation is generally poorly explored for
physiological parameters. Such physiological variability is important, as it can provide insight into
the capacity for evolutionary adaptation and how animals may cope with anthropogenic climate
change. Insect vectors of human and animal diseases, such as tsetse flies (Diptera, Glossinidae)
which carry trypanosomes, are of particular interest. Predictions of tsetse fly (Glossina spp.) range
expansion, possibly paralleled by increased disease occurrence, have been made under future
climate scenarios. Moreover, since there are generally strong relationships between abiotic variables
(e.g. temperature and moisture availability), population dynamics, distribution and abundance,
determining the physiological mechanisms influencing such relationships has utility for predictive
modelling of spatial and temporal changes in tsetse fly distributions. I investigated physiological
variation among individuals and populations, focusing mainly on Glossina spp. but using other
arthropods to address certain issues. Specifically, I show the following: i) metabolic rate is
repeatable (intra-class correlation coefficient) within individuals, and may be influenced by several
factors such as age, gender, body mass and pregnancy; ii) while metabolic rate is repeatable within
individuals, it remains unaltered with acclimation to laboratory conditions from field collection; iii)
within a population, metabolic rate-temperature relationships are surprisingly invariant among
physiological states such as age, gender, feeding status, pregnancy and temperature acclimation; iv)
the magnitude of the effect of temperature acclimation differs among traits, in that upper thermal
tolerances respond less than lower thermal tolerances, while metabolic rate responds to heat but not
to cold. Water loss rate is relatively unresponsive to either treatment; v) plasticity can account for
most inter-population variation in physiological traits related to climatic stress resistance (e.g.
thermotolerances and desiccation rates) in the natural environment; vi) adult physiological
performance responds differently to developmental and adult acclimation, such that marked traitspecific
variation occurs, and combinations of both developmental and adult plasticity can result in
further alteration of adult performance. These results have implications for the evolution of stress
resistance to abiotic factors in these and other arthropods. I conclude by discussing the potential
physiological patterns linking population dynamics and abiotic factors, with particular reference to
tsetse flies. / AFRIKAANSE OPSOMMING: Binne arthropoda, is tussen-individu en tussen-bevolking variasie in die algemeen sleg bestudeer vir
fisiologiese parameters. Hierdie fisiologiese variasie is belangrik want dit kan insig gee in die mate
van evolusionêre aanpassing en hoe diere antropogenies klimaatsverandering kan hanteer. Dit is
veral belangrik in die geval van insekte wat mens- en diersiektes kan dra, soos tsetse vlieë (Diptera,
Glossinidae) wat trypanosome oordra. In die geval van tsetse vlieë (Glossina spp.) is voorspellings
vir verhoogde verspreiding, en gevolglik verhoogde siekte voorkoms, gemaak onder toekomstige
voorkoms klimaat senario’s. Verder, aangesien daar in die algemeen sterk verwantskappe tussen
abiotiese parameters (bv. temperatuur en water beskikbaarheid), bevolkingsdynamika, verspreiding
en voorkoms is, is die bepaling van die fisiologiese meganisme, wat ‘n invloed het op hierdie
verwantskappe, nuttig vir die voorspelling van tsetse oor spasie en tyd. Hier, met hoofsaaklik die
gebruik van Glossina spp., maar ook ander arthropoda wanneer dit nodig is, word navorsing wat
fisiologiese variasie tussen individue en bevolkings aanspreel voorgelê. Spesifiek, word dit gewys
dat i) metaboliese tempo is herhaalbaar (intra-klas korrelasie koeffisient) binne individue, alhowel
metaboliese tempo kan beinvloed word deur faktore soos ouderdom, geslag, liggaamsmassa en
swangerskap, ii) terwyl metaboliese tempo binne individue herhaalbaar is, verander dit nie met
akklimasie na laboratorium toestande vanaf versameling in die veld, iii) binne ‘n bevolking
metaboliese tempo-temperatuur verwantskappe is verbasend eenders tussen fisiologiese toestande
soos ouderdom, geslag, voeding staat, swangerskap en temperatuur akklimasie, iv) die grootte van
die effek van temperatuur akklimasie verskil tussen eienskappe, en die boonste termiese limiete
reageer minder as laer termiese limiete, terwyl metaboliese tempo reageer op hitte maar nie koue
nie, en waterverlies tempo is relatief terughoudend tot enige temperatuur toestand, v) buigbaarheid
kan die meeste van inter-bevolkingsvariasie in fisiologiese eienskappe van klimaatstres
weerstandsvermoë (termiese toleransie en uitdrogingstempo) in die natuurlike omgewing verklaar,
vi) volwasse fisiologiese prestasie reageer verskillend op ontwikkelende en volwasse akklimasie,
soveel dat eienskap-spesifieke variasie kan voorkom, en ‘n kombinasie van beide ontwikkelende en
volwasse buigbaarheid ‘n verskillende volwasse prestasie tot gevolg kan hê. Hierdie resultate het
implikasies vir die evolusie van weerstandsvermoë tot abiotiese faktore in hierdie en ander
arthropoda. Hierdie tesis word afgesluit met ‘n bespreeking van die moontlikke fisiologiese patrone
wat bevolkingsdinamika en abiotiese faktore kan verbind, met ‘n fokus op tsetse vlieë.
|
14 |
Vectors and transmission routes of animal trypanosomiasis on the Jos Plateau north central NigeriaOlaniyan, Oluwashola January 2016 (has links)
Tsetse flies, Glossina species, are the biological vectors of Trypanosoma species which cause animal African trypanosomiases (AAT) in livestock (especially cattle) in sub-Saharan Africa. This disease is often fatal without treatment and negatively impacts on rural, agricultural and economic development. On the Jos Plateau, north central Nigeria, AAT was historically of little significance due to the presumed absence of tsetse and Fulani pastoralists were encouraged to settle there. But over the last 30 years, the disease has become widespread and highly prevalent in the area. This has been attributed to the expansion of tsetse on the plateau, frequent migrations of cattle to areas with higher tsetse densities and the presence of other biting flies which serve as mechanical vectors. In the current study, the presence and abundance of tsetse was determined in selected villages using biconical tsetse trap surveys. The low number of flies trapped suggests that tsetse expansion has been very limited within the plateau but the fact that trypanosome DNA was present in over half of these flies implicates them in AAT transmission. The migration of a herd of cattle was also tracked and during the period, blood samples were collected from the cattle and examined for trypanosomes using molecular techniques. Despite prophylactic treatment and deltamethrin sprays, results showed that a significant proportion of the animals (52%) had become infected with T. vivax over the migration period. Tsetse flies (G. palpalis) were also slightly more abundant in some of parts of the migration area. Potential mechanical vectors (Stomoxys spp. and Tabanidae) were trapped and results obtained from the examination of their mouthparts for trypanosomes indicate their involvement in transmission. However, it is difficult to make any definite conclusions about their overall contribution which is thought to be minimal and more studies are needed to clarify their significance. It is concluded that trypanosomiasis risk from tsetse on the Jos Plateau is currently low and seasonal migration appears to be the main driver of AAT transmission by exposing cattle to more tsetse for longer periods. Other biting flies may play a limited role which remains undetermined. Continued monitoring of cattle and tsetse across the plateau over the next few years is important and the careful use of trypanocides and insecticide treated cattle is recommended as an appropriate control strategy.
|
15 |
An individual-based model of tsetse fly populations dynamics : modelling an extensive mark-release-recapture experimentFerreira, Roux-Cil 04 1900 (has links)
Thesis (MComm)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Tsetse flies (Glossina spp), native to mid-continental Africa, are the vectors
of trypanosomes that causes human (sleeping sickness) and animal (nagana)
trypanosomiasis. Vector control plays a major role in alleviating the burden
of the disease. Mathematical models of tsetse population dynamics provide
insights into how best to manage these control efforts.
A major mark-recapture experiment, carried out in Zimbabwe, provided
valuable information on tsetse population dynamics, but the analyses so far
published could be improved on because not all of the information available
on the marking procedure was used.
We have constructed an individual-based model that follows the life of individual
tsetse flies, their progeny and, in particular, the sequence of occasions
on which individual flies were captured and given distinctive marks. We have
access to comprehensive data from the tsetse fly mark-release-recapture experiment
carried out on Antelope Island, Lake Kariba, Zimbabwe. In order
to calibrate or validate the model, we model both the growth of the introduced
tsetse population and the mark-recapture process. We have compared
the model outputs to the original data and recommend processes that may be
followed for model calibration.
It is possible to construct an individual-based model that adequately models
tsetse fly populations. Whereas the focus of this study has been on modelling
the mark-recapture study, the individual-based model could also be used
in more general settings to model the growth, and reduction in fly numbers,
changes in age structure, species and gender ratios and the acquisition of trypanosome
infections by individual flies. This model can thus be used to investigate the effect of various factors on tsetse fly and trypanosome, population
dynamics as well as on the performance of various control techniques effecting
fly mortality and disease transmission. / AFRIKAANSE OPSOMMING: Tsetsevlieë (Glossina spp), inheems aan sentraalkontinentale Afrika, is die draers
van trypanosomen wat trypanosomiasis by die mens (slaapsiekte) en by
diere (nagana) veroorsaak. Die beheer van draers speel 'n belangrike rol om
die las wat die siekte veroorsaak, te verlig. Wiskundige modelle van tsetse bevolkingsdinamika
bied insigte oor hoe om beheerpogings die beste te bestuur.
'n Belangrike merk-hervang eksperiment, wat in Zimbabwe uitgevoer is,
bevat waardevolle inligting oor tsetse bevolkingsdinamika. Die ontleding daarvan,
wat tot dusver gepubliseer is, kan egter verbeter word aangesien nie al
die inligting beskikbaar in die merkprosedure, gebruik is nie.
Ons het 'n individu-gebaseerde model saamgestel wat die lewens van individuele
tsetsevlieë en hul nageslagte volg, in besonder die volgorde waarop
individuele vlieë gevang en herkenbaar gemerk is. Ons het toegang tot omvattende
data van die tsetsevlieg merk-vrylaat-hervang eksperiment wat uitgevoer
is op Antelope Eiland, Karibadam, Zimbabwe. Ten einde die model te kalibreer
of om die model se geldigheid te bevestig, modelleer ons beide die groei
van die ingevoerde tsetse bevolking en die merk-hervangs metode. Ons vergelyk
die modeluitsette met die oorspronklike data en beveel prosesse aan wat
gevolg kan word om die model te kalibreer.
Dit is moontlik om 'n individu-gebaseerde model saam te stel wat tsetsevliegbevolkings
voldoende moduleer. Terwyl hierdie studie die modellering
van die merk-hervang data bestudeer, kan die individueel-gebaseerde model
ook gebruik word in meer algemene gevalle vir die modellering van die vermeerdering
en vermindering in vlieë getalle, veranderinge in die ouderdomstruktuur,
spesies en geslagverhoudings en die verwerwing van trypanosomen
infeksies deur individuele vlieë. Hierdie model kan dus gebruik word om die
effek te ondesoek van verskeie faktore op die tsetsevlieg en trypanosomen, populasiedinamiek
sowel as die prestasie van verskillende beheertegnieke rakende
vliegsterftes en siekte-oordrag.
|
16 |
Investigating the simultaneous effect of age and temperature on the population dynamics of female tsetse fliesElama Ameh, Josephine, Ochigbo, Josephine Elanma 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Age and temperature are two factors that affect mortality in adult tsetse flies. Both are found
to be very important, but the simultaneous effect of these factors on the mortality rate have
not been studied. This study seeks to address this, with an application to a population of
female tsetse, using a model based on partial differential equations. Adult mortality is agedependent
and is modelled as the sum of two exponentials, with four parameters (coefficients
of each exponential): numerical analysis of a population model with this mortality structure
predicts exponential growth. Analysis of each of the parameters through parameter variation
shows that two of these parameters control the mortality of the nulliparous (ages 0 − 10
days) flies only while the other two only take care of flies of mature ages. Measurement of
the impact of these parameters on the mortality of tsetse of different ages by the normalized
forward sensitivity index method is also carried out. This is followed by fitting the model
based on the age-dependent mortality along with a constant tsetse birth rate to data representing
the catches of female Glossina pallidipes at Rekomitjie Research station, Zimbabwe.
Considering a three parameter adult tsetse mortality, parameter analysis shows the effect of
one of the parameters to affect the mortality of flies of all ages while a second controls only the
mature tsetse flies of reproductive ages. A further analysis resulted in the estimate of these
parameters as functions of temperature, thereby leading to the establishment of an age and
temperature-dependent adult tsetse mortality. Using data for the daily average temperature
records obtained in 1981 on Antelope Island, Lake Kariba, Zimbabwe, daily changes in the
pupal duration (adult tsetse birth rate) changes negatively with temperature change. Incorporating
this (temperature-dependent ) birth rate into the model, together with the established
age and temperature-dependent adult mortality, the adult tsetse population dynamics is explored
numerically. The latter model is then fitted to population data of female Glossina
morsitans morsitans obtained from the same Island and for the same period as used for
the temperature data. The data suggests peak tsetse population to be in the month of July
and lowest in the month of December. The first quarter of the year is predicted to be most
favorable for breeding tsetse while the second, showed a period of stable growth rate and a
time of tsetse abundance. In addition, the dynamics with both age and temperature showed a
non-uniform daily population growth contrary to that with age effect only. This study has enhanced
our understanding of tsetse population dynamics for age and temperature-dependent
adult mortality with temperature-dependent pupal duration and suggests the period of tsetse
abundance on Antelope Island. / AFRIKAANSE OPSOMMING: Geen opsomming in Afrikaans.
|
17 |
Molecular characterization of trypanosomes commonly found in cattle, wild animals and tsetse flies in Kwazulu-Natal, South Africa, 2005-2007Ledoka, Mpho Victoria 29 July 2009 (has links)
The objective of this study was to use molecular biological reagents (primers targeting different genomic loci) and methods (PCR and RFLP) to detect and characterize trypanosomes in cattle, wild animals and tsetse flies in KwaZulu-Natal, thus contributing to improved understanding of the genetic diversity of trypanosome species infecting cattle at the game/livestock interface in the KwaZulu-Natal Province of South Africa. Primers based on sequences of different loci in the trypanosome genome were used in conducting polymerase chain reactions (PCRs) on samples collected from cattle at 14 diptanks and one commercial farm around the Hluhluwe-Umfolozi Game Reserve, wild animals within Hluhluwe-Umfolozi Game Reserve and tsetse flies from the commercial farm, Hluhluwe-Umfolozi Game Reserve and two other Game Reserves. Trypanosome isolates were grown under laboratory conditions in cattle, rodents and culture medium for molecular characterizations. Overall, a total of 673 cattle, 266 tsetse flies, 141 buffaloes and 6 rhinoceros samples were analyzed. The following observations were made: two species of trypanosomes are present in KZN; T.congolense and T. vivax. The two species were found as single and as mixed infections in cattle. There are two genotypic groups of T. congolense in KZN; the Savannah- and the Kilifi-type. The two genotypic groups were found as mixed infections in cattle and in tsetse flies. Lastly, there are at least five “genomic variants” of Savannah-type T. congolense in KZN. The infection rate in cattle ranged from 5.2-91%; in tsetse flies, 11-97.5% and in wild animals it was 4.3%. Mixed infection of T. congolense and T. vivax were only observed in samples from one diptank. Mixed infections of Savannah- and Kilifi-type T. congolense were observed in samples from Boomerang commercial farm, and in tsetse flies. Copyright / Dissertation (MSc)--University of Pretoria, 2008. / Veterinary Tropical Diseases / unrestricted
|
18 |
Modelling the control of tsetse and African trypanosomiasis through application of insecticides on cattle in Southeastern UgandaKajunguri, Damian 03 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In Uganda, cattle are an important reservoir of Trypanosoma brucei rhodesiense, a parasite
that causes human African trypanosomiasis or sleeping sickness. We developed mathematical
models to examine the transmission of T. b. rhodesiense by tsetse vector species,
Glossina fuscipes fuscipes in a host population that consists of humans, domestic and wild
mammals, and reptiles. The models were developed and analysed based on the situation in
Tororo district in Southeastern Uganda, where sleeping sickness is endemic and which has a
cattle and human population of 40, 000 and 500, 000, respectively. Assuming populations of
cattle and humans only, the impact of mass chemoprophylaxis and vector control through
insecticide-treated cattle (ITC) is evaluated. Keeping 12% or 82% of the cattle population
on insecticides that have an insecticidal killing effect of 100% at all times or trypanocides
that have 100% efficacy, respectively, can lead to the control of T. b. rhodesiense in both
humans and cattle. Optimal control of T. b. rhodesiense is shown to be achieved through
ITC alone or a combination of chemoprophylaxis and ITC, the former being the cheapest
control strategy. Allowing for the waning effect of insecticides and including wildhosts,
T. b. rhodesiense control can be achieved by keeping 21% or 27% of the cattle population
on insecticides through whole-body or restricted application, respectively. Restricting
the treatment of insecticides to adult cattle only would require 24% or 33% of the adult
cattle population to be kept on insecticides through whole-body or restricted application,
respectively, to control T. b. rhodesiense. A cost-effectiveness and benefit-cost analysis of
using ITC to control T. b. rhodesiense show that restricted application of insecticides is
a cheaper and more beneficial strategy compared to whole-body treatment. The results of
the study show that the restricted application of insecticides on cattle provides a cheap,
safe and farmer-based strategy for controlling tsetse and trypanosomiasis. / AFRIKAANSE OPSOMMING: In Uganda is beeste ’n belangrike reservoir van Trypanosoma brucei rhodesiense, ’n parasiet
wat tripanosomiase of slaapsiekte in mense veroorsaak. Ons het wiskundige modelle ontwikkel
wat die oordrag van T. b. Rhodesiense deur tesetse vektor spesies, Glossina fuscipes
fuscipes in ’n draer populasie wat bestaan uit mense, mak en wilde diere en reptiele, ondersoek.
Die modelle was ontwikkel en geanaliseer gebaseer op die oordrag situasie in die
Tororo distrik in Suidoostelike Uganda, ’n gebied waar slaapsiekte endemies is en wat ’n
populasie van 40, 000 beeste en 500, 000 mense het. Die impak van massa chemoprofilakse
en vektor beheer deur insekdoder-behandelde beeste is gevalueer onder die aanname van
bees en mens populasies alleenlik. Beheer oor T. b. Rhodesiense in beide mense en beeste
kan verkry word deur of 12% van die bees populasie te behandel met ’n insekdoder wat
100% effektief is ten alle tye of 82% van die bees populasie te behandel met tripanosiedes
wat 100% effektief is. Daar is aangetoon dat optimale beheer van T. b. Rhodesiense
bereik kan word deur die gebruik van insekdoders alleenlik of ’n kombinasie van insekdoders
en chemoprofilakse, hoewel eersgenoemde die goedkoopste strategie is. Wanneer die
kwynende effek van insekdoders asook wilde diere as draers in ag geneem word, kan T.
b. Rhodesiense beheer verkry word deur 21% van beeste se hele liggaam met insekdoders
te behandel of 27% gedeeltelik te behandel. As slegs volwasse beeste met insekdoders
behandel word, moet 24% se hele liggaam of 33% gedeeltelik behandel word vir beheer
van T. b. Rhodesiense. ’n Koste-effektiwiteit en voordeel-koste analise van insekdoders as
beheermaatstaf vir T. b. Rhodesiense toon aan dat gedeeltelike behandeling van die bees
se liggaam die goedkoper en meer voordelige strategie is in vergelyking met behandeling
van die hele liggaam. Die resultate van die studie wys dat gedeeltelike behandeling van
beeste met insekdoders ’n goedkoop, veilige en landbouer-gebaseerde strategie is om tsetse
en tripanosomiase te beheer.
|
19 |
Coding of tsetse repellents by olfactory sensory neurons: towards the improvement and the development of novelSouleymane, Diallo January 2020 (has links)
Philosophiae Doctor - PhD / Tsetse flies are the biological vectors of human and animal trypanosomiasis and hence representant medical and veterinary importance. The sense of smell plays a significant role in tsetse and its ecological interaction, such as finding blood meal source, resting, and larvicidal sites and for mating. Tsetse olfactory behaviour can be exploited for their management; however, olfactory studies in tsetse flies are still fragmentary. Here in my PhD thesis, using scanning electron microscopy, electrophysiology, behaviour, bioinformatics and molecular biology techniques, I have investigated tsetse flies (Glossina fuscipes fuscipes) olfaction using behaviourally well studied odorants, tsetse repellent by comparing with attractant odour. Insect olfaction is mediated by olfactory sensory neurons (OSNs), located in olfactory sensilla, which are cuticular structures exposed to the environment through pore and create a platform for chemical communication. In the sensilla shaft the dendrite of OSNs are housed, which are protected by called the sensillum lymph produced by support cells and contains a variety of olfactory proteins, including the odorant binding protein (OBP) and chemosensory proteins (CSP). While on the dendrite of OSNs are expressed olfactory receptors. In my PhD, studies I tried to decipher the sense of smell in tsetse fly. In the second chapter, I demonstrated that G. f. fuscipes is equipped with diverse olfactory sensilla, that various from basiconic, trichoid and coeloconic. I also demonstrated, there is shape, length, number difference between sensilla types and sexual dimorphism. There is a major difference between male and female, while male has the unique basiconic sensilla, club shaped found in the pits, which is absent from female pits. In my third chapter, I investigated the odorant receptors which are expressed on the dendrite of the olfactory sensory neurons (OSNs). G. f. fuscipes has 42 ORs, which were not functionally characterised. I used behaviourally well studied odorants, tsetse repellents, composed of four components blend. I demonstrated that tsetse repellent is also a strong antifeedant for both G. pallidipes and G. f. fuscipes using feeding bioassays as compared to the attractant odour, adding the value of tsetse repellent. However, the attractant odour enhanced the feeding index. Using DREAM (deorphanization of receptors based on expression alterations of mRNA levels). I found that in G. f. fuscipes, following a short in vivo exposure to the individual tsetse repellent component as well as an attractant volatile chemical, OSNs that respond to these compounds altered their mRNA expression in two opposite direction, significant downregulation and upregulation in their number of transcripts corresponding to the OR that they expressed and interacted with odorant. Also, I found that the odorants with opposite valence already segregate distinctly at the cellular and molecular target at the periphery, which is the reception of odorants by OSNs, which is the basis of sophisticated olfactory behaviour. Deorphanization of ORs in none model insect is a challenge, here by combining DREAM with molecular dynamics, as docking score, physiology and homology modelling with Drosophila a well-studied model insects, I was able to predict putative receptors of the tsetse repellent components and an attractant odour. However, many ORs were neutral, showing they were not activated by the odorants, demonstrating the selectivity of the technique as well as the receptors. In my fourth chapter, I investigated the OBPs structures and their interaction with odorants molecules. I demonstrated that OBPs are expressed both in the antenna, as well as in other tissues, such as legs. I also demonstrated that there are variations in the expression of OBPs between tissues as well as sexes. I also demonstrated that odorants induced a fast alteration in OBP mRNA expression, some odorants induced a decrease in the transcription of genes corresponding to the activated OBP and others increased the expression by many fold in OBPs in live insect, others were neutral after 5 hours of exposure. Moreover, with subsequent behavioural data showed that the behavioural response of G. f. fuscipes toward 1-octen-3-ol decreased significantly when 1-octen-3-ol putative OBPs were silenced with feeding of double-stranded RNA (dsRNA). In summary, our finding whereby odorant exposure affects the OBPs mRNA, their physiochemical properties and the silencing of these OBPs affected the behavioural response demonstrate that the OBPs are involved in odour detection that affect the percept of the given odorant. The expression of OBPs in olfactory tissues, antenna and their interaction with odorant and their effect on behavioural response when silenced shows their direct involvement in odour detection and reception. Furthermore, their expression in other tissues such as legs indicates they might also have role in other physiological functions, such as taste.
|
20 |
Lutte contre les mouches tsé-tsé en Afrique de l’Ouest : optimisation de l’utilisation de la technique de l’insecte stérile / Control of tsetse flies in West Africa : optimizing the use of the sterile insect techniquePagabeleguem, Soumaïla 15 December 2015 (has links)
En Afrique sub-saharienne, près de 10 millions de km2 de terres, les plus fertiles en productions fourragères et agricoles, sont infestées de mouches tsé-tsé limitant ainsi les initiatives de développement d’une agriculture durable. Les tsé-tsé transmettent des trypanosomes qui sont responsables des trypanosomoses animales et humaines africaines. En 2000, les Chefs d’Etats et de Gouvernements africains ont décidé de redoubler d’efforts pour lutter contre les mouches tsé-tsé et les trypanosomoses en créant la Pan African Tsetse and Trypanosomosis Eradication Campaign (PATTEC). Dans ce contexte, le gouvernement sénégalais a initié un programme d’éradication des glossines dans la zone des Niayes en utilisant une souche de Glossina palpalis gambiensis originaire du Burkina Faso. La présente thèse visait à optimiser l’utilisation de la technique de l’insecte stérile (TIS) en Afrique de l’Ouest pour lutter contre les glossines. Un dispositif de transport sur de longues distances de pupes matures a été développé et validé à partir de pupes mâles de G. p. gambiensis produites et irradiées à Bobo-Dioulasso, Burkina Faso et à Bratislava, Slovaquie (irradiation faite à Seibersdorf, Autriche) et transportées par voie aérienne jusqu’à Dakar, Sénégal. Le dispositif constitué d’une boîte isotherme et des packs S8 a permis de maintenir les pupes à une température de 10 ± 3°C et de les transporter pendant 2-3 jours jusqu’au centre d’émergence de l’ISRA, pour produire des mâles stériles utilisables pour la technique de l’insecte stérile. Un contrôle qualité a été réalisé sur un échantillon de 50 pupes prélevé dans chaque lot de pupes (minimum 2 lots par envoi) pour déterminer l’aptitude d’envol des mâles stériles et leur survie sous stress (à jeun). Le reste des pupes utilisé pour les lâchers sur le terrain a été considéré comme témoin. Le protocole qualité décrit permettra un suivi précis de la qualité des mâles stériles utilisés dans les programmes opérationnels d’éradication dans le cadre de la PATTEC. Un outil moléculaire de discrimination de mâles stériles lâchés et sauvages a également été développé à partir du gène mitochondrial COI (cytochrome oxydase) et a montré que les séquences COI des mouches lâchées (produites en insectarium) sont 100% identiques entre elles et différentes de celles des mouches sauvages. Par ailleurs, afin de déterminer les conditions optimales d’élevage de souches de G. p. gambiensis et de déterminer la souche qui sera la plus adaptée à tel ou tel environnement ou pays dans le cadre d’une lutte avec une composante lâcher de mâles stériles, les traits de vie (survie et fécondité) de trois souches de G. p. gambiensis (souches originaires du Burkina Faso (BKF), Sénégal (SEN) et souche introgressée (SENbkf) ont été évalués dans différentes conditions de températures et d’humidités relatives. La température optimale d’élevage en masse a été de 25 ± 1°C, 24,6 ± 1°C et 23,9 ± 1°C pour BKF, SENbkf et SEN respectivement. La variation de l’humidité relative (entre 40 et 75%) a eu très peu d’influence sur la survie et la fécondité. La souche BKF a mieux résisté à de fortes températures que les souches SEN et SENbkf, mais la température limite de survie a été de 32°C pour les trois souches. / In sub-Saharan Africa, nearly 10 million km² of land, the most fertile for animal and agricultural productions, are infested with tsetse flies limiting all development initiatives for sustainable agriculture. Tsetse flies transmit trypanosomes that cause human and animal african trypanosomosis, a debilitating disease of humans (sleeping sickness) and livestock (nagana). In 2000, the African Heads of State and Government decided to increase efforts to address the tsetse and trypanosomosis problem on the African continent and created the Pan-African Tsetse and Trypanosomosis Eradication Campaign (PATTEC). In this context, the Government of Senegal initiated a tsetse eradication program in the Niayes area using a Glossina palpalis gambiensis strain originating from Burkina Faso. The objective of this thesis was to optimize the use of the sterile insect technique (SIT) in West Africa in order to control the tsetse flies. A system to transport mature pupae over long distances has been developed and validated for male G. p. gambiensis pupae produced and irradiated either in Bobo-Dioulasso, Burkina Faso or in Bratislava, Slovakia (irradiation done in Seibersdorf, Austria) and then transported by air to Dakar, Senegal. The system, constituted of an insulated box and S8 packs, allowed the maintenance of pupae at a temperature of 10 ± 3°C and their transport during 2-3 days to the emergence center of ISRA, where they molted into sterile males which were used for the sterile insect technique.A quality control was carried out on a sample of 50 pupae from each batch (at least 2 batches per shipment) to determine the flight ability of sterile males and their survival under stress conditions (without feeding). The remaining emerging pupae were released in the target area of the eradication programme and were considered as control group. The described protocol for quality control will allow accurate monitoring of the quality of sterile males used in operational eradication programs organized in the context of PATTEC.A molecular tool to distinguish between sterile and wild males was also developed using the mitochondrial gene COI (cytochrome oxidase). We showed that COI sequences of released flies (reared in insectary) are 100% identical and different from those of wild flies.Furthermore, in order to determine the optimal rearing conditions for G. p. gambiensis strains and to identify the strain that would be the best adapted to a particular environment or country in the context of a control with an SIT component, life history (survival and fecundity) of three G. p. gambiensis strains (strains originating from Burkina Faso (BKF), Senegal (SEN), and an introgressed strain (SENbkf)) were investigated at different temperatures and relative humidity conditions. The optimal temperature for the mass-rearing was 25 ± 1°C, 24.6 ± 1°C and 23.9 ± 1°C for BKF, SENbkf and SEN respectively. The relative humidity ranging from 40 to 75% had very little influence on the survival and fecundity. The BKF strain resisted better at higher temperatures than the SENbkf and SEN strains but the temperature limit for survival was about 32°C for all three strains.
|
Page generated in 0.032 seconds