Tsetse Fly Species Research Articles

Impact of Salivary Gland Hypertrophy Virus Infection on the Mating Success of Male Glossina pallidipes: Consequences for the Sterile Insect Technique

Many species of tsetse flies are infected by a virus (GpSGHV) that causes salivary gland hypertrophy (SGH). Female Glossina pallidipes (Austen) with SGH symptoms (SGH+) have reduced fecundity and SGH+ male G. pallidipes are unable to inseminate female flies. Consequently, G. pallidipes laboratory colonies with a high prevalence of SGH have been difficult to maintain and have collapsed on several occasions. To assess the potential impact of the release of SGH+ sterile male G. pallidipes on the efficacy of an integrated control programme with a sterile insect technique (SIT) component, we examined the mating efficiency and behaviour of male G. pallidipes in field cages in relation to SGH prevalence. The results showed in a field cage setting a significantly reduced mating frequency of 19% for a male G. pallidipes population with a high prevalence of SGH (83%) compared to 38% for a male population with a low prevalence of SGH (7%). Premating period and mating duration did not vary significantly with SGH status. A high percentage (>80%) of females that had mated with SGH+ males had empty spermathecae. The remating frequency of female G. pallidipes was very low irrespective of the SGH status of the males in the first mating. These results indicate that a high prevalence of SGH+ in G. pallidipes not only affects colony stability and performance but, in view of their reduced mating propensity and competitiveness, releasing SGH+ sterile male G. pallidipes will reduce the efficiency of a sterile male release programme.

The Antiviral Drug Valacyclovir Successfully Suppresses Salivary Gland Hypertrophy Virus (SGHV) in Laboratory Colonies of Glossina pallidipes

Many species of tsetse flies are infected with a virus that causes salivary gland hypertrophy (SGH) symptoms associated with a reduced fecundity and fertility. A high prevalence of SGH has been correlated with the collapse of two laboratory colonies of Glossina pallidipes and colony maintenance problems in a mass rearing facility in Ethiopia. Mass-production of G. pallidipes is crucial for programs of tsetse control including the sterile insect technique (SIT), and therefore requires a management strategy for this virus. Based on the homology of DNA polymerase between salivary gland hypertrophy virus and herpes viruses at the amino acid level, two antiviral drugs, valacyclovir and acyclovir, classically used against herpes viruses were selected and tested for their toxicity on tsetse flies and their impact on virus replication. While long term per os administration of acyclovir resulted in a significant reduction of productivity of the colonies, no negative effect was observed in colonies fed with valacyclovir-treated blood. Furthermore, treatment of a tsetse colony with valacyclovir for 83 weeks resulted in a significant reduction of viral loads and consequently suppression of SGH symptoms. The combination of initial selection of SGHV-negative flies by non-destructive PCR, a clean feeding system, and valacyclovir treatment resulted in a colony that was free of SGH syndromes in 33 weeks. This is the first report of the use of a drug to control a viral infection in an insect and of the demonstration that valacyclovir can be used to suppress SGH in colonies of G. pallidipes.

Prevalence study of bovine trypanosomosis and tsetse density in selected villages of Arbaminch, Ethiopia

A cross-sectional study was carried out with aimed at determining the prevalence of bovine trypanosomosis and apparent tsetse density in two selected villages of Arba Minch Woreda, from November, 2009 to April, 2010. Blood samples were collected from 384 randomly selected cattle to detect the prevalence of trypanosomes using buffy coat method. The overall infection rate 4.43% (N=17) was recorded. The cattle are invariably infected with different species of trypanosome parasite and among these Trypanosoma congolense is the commonest (82.35%) followed by co-infection of Trypanosoma viviax and T. congolense (11.76%), and T. vivax (5.88%). This study showed a significant difference (p<0.05) in trypanosomosis infection rate among poor, medium and good body condition animals. Poor body condition animals were highly affected compared to medium and good body condition. The mean PCV value of parasitemic and aparasitaemic animals was recorded as 20.94 and 23.55%, respectively. In each study area, entomological surveys were conducted using NGU trap and it indicated that G. pallidipes were the only tsetse fly species caught in the study area along with other biting flies like stomoxys and tabanus. Apparent tsetse flies density of 0.312 and 29.624 flies/trap/day were recorded in Fura and Eligo villages, respectively and the overall apparent density of tsetse flies in the study area was 14.97 flies/trap/day. Due to its impact on livestock production, emphasis should be given for the control and prevention of trypanosomosis infection and its vectors. Key words: Bovine trypanosomosis, prevalence, NGU trap, Tsetse fly, Southern Ethiopia.

Detection and characterization of Wolbachia infections in laboratory and natural populations of different species of tsetse flies (genus Glossina)

BackgroundWolbachia is a genus of endosymbiotic α-Proteobacteria infecting a wide range of arthropods and filarial nematodes. Wolbachia is able to induce reproductive abnormalities such as cytoplasmic incompatibility (CI), thelytokous parthenogenesis, feminization and male killing, thus affecting biology, ecology and evolution of its hosts. The bacterial group has prompted research regarding its potential for the control of agricultural and medical disease vectors, including Glossina spp., which transmits African trypanosomes, the causative agents of sleeping sickness in humans and nagana in animals.ResultsIn the present study, we employed a Wolbachia specific 16S rRNA PCR assay to investigate the presence of Wolbachia in six different laboratory stocks as well as in natural populations of nine different Glossina species originating from 10 African countries. Wolbachia was prevalent in Glossina morsitans morsitans, G. morsitans centralis and G. austeni populations. It was also detected in G. brevipalpis, and, for the first time, in G. pallidipes and G. palpalis gambiensis. On the other hand, Wolbachia was not found in G. p. palpalis, G. fuscipes fuscipes and G. tachinoides. Wolbachia infections of different laboratory and natural populations of Glossina species were characterized using 16S rRNA, the wsp (Wolbachia Surface Protein) gene and MLST (Multi Locus Sequence Typing) gene markers. This analysis led to the detection of horizontal gene transfer events, in which Wobachia genes were inserted into the tsetse flies fly nuclear genome.ConclusionsWolbachia infections were detected in both laboratory and natural populations of several different Glossina species. The characterization of these Wolbachia strains promises to lead to a deeper insight in tsetse flies-Wolbachia interactions, which is essential for the development and use of Wolbachia-based biological control methods.

Catch Composition of Tsetse Flies (&lt;i&gt;Glossina: Glossinidae&lt;/i&gt;)

Problem statement: A study to determine the composition of tsetse flies species was conducted between January and December, 2007 in Kamuku National Park, Nigeria, using Biconical and Nitse traps. Tsetse flies were trapped along gallery forest in five streams for two trapping days and were collected daily. Approach: All tsetse flies caught were identified to species level, sexed, separated into teneral and non-teneral, hunger staged and Mean Hunger Stage computed. Fly density were calculated, the age structure examined using wing fray techniques for males and ovarian technique for females; the reproductive status of female flies were assessed. Two species of tsetse flies (Glossina palpalis palpalis robineau-desvoidy and Glossina tachinoides Westwood) were caught in total of five hundred and two (502) flies. Out of these, 309(61.6%) Glossina tachinoides and 193(38.4%) G. palpalis were caught. Male catches (309, 61.6%) were significantly (P < 0.05) higher than females (193, 38.4%) also, the teneral flies (289, 57.6%) were more than the non-teneral flies (213, 42.4%). The Mean Hunger Stage (MHS) of 3.6 obtained indicated a hungry fly population. Fly density was generally low (0.1fly/trap/day) and varied between months with highest density (3flies/trap/day) occurring in February and lowest (0.2 fly/trap/day) in July. Results: The estimated mean age for males was 11 days and females were 8 days. The insemination rate of 93.8% generally was high, G. tachinoides recorded 95.5% more than G. palpalis of 91.6%. Whereas parity rate (25.8%) was low; G. palpalis was 37.4% while G. tachinoides parity rate is 17.2%. Conclusion: The study shows that two species of tsetse flies abound in the park although at low densities their presence may bear semblance to Trypanosomiasis and its impact to ecotourism.

Entomological survey in the historical focus of human African trypanosomiasis of Bendje (Gabon)

La situation de la maladie du sommeil est très peu connue au Gabon. De nombreux foyers historiques n’ont pas été prospectés depuis plus de 15 ans. Le foyer historique de Bendjé fournit régulièrement quelques cas, dépistés passivement, qui concernent le plus souvent des pêcheurs dont il est a priori difficile de déterminer le lieu probable de contamination du fait de leur grande mobilité au cours de leurs activités. La présence des hommes infectés dans ce foyer historique pourrait favoriser son réveil s’il existe un contact étroit entre les différents éléments potentiellement présents du cycle épidémiologique (homme, vecteur, trypanosome). Afin de vérifier l’existence éventuelle d’un risque trypanosomien dans ce foyer, nous y avons mené une enquête entomologique. Des pièges ont été posés dans des biotopes fréquentés par l’homme et laissés en place pendant quatre jours. Trois espèces de glossines (Glossina palpalis palpalis, G. pallicera newsteadi et G. caliginea) ont été capturées et deux espèces de trypanosomes (Trypanosoma vivax et T. brucei s.l.) identifiées par PCR. Ces résultats suggèrent l’existence d’un cycle de transmission animal. Le contact entre les hommes et les glossines est particulièrement étroit dans tous les types de site prospectés, à l’exception de la mangrove.

Tsetse Salivary Gland Hypertrophy Virus: Hope or Hindrance for Tsetse Control?

Many species of tsetse flies (Diptera: Glossinidae) are infected with a virus that causes salivary gland hypertrophy (SGH), and flies with SGH symptoms have a reduced fecundity and fertility. The prevalence of SGH in wild tsetse populations is usually very low (0.2%–5%), but higher prevalence rates (15.2%) have been observed occasionally. The successful eradication of a Glossina austeni population from Unguja Island (Zanzibar) using an area-wide integrated pest management approach with a sterile insect technique (SIT) component (1994–1997) encouraged several African countries, including Ethiopia, to incorporate the SIT in their national tsetse control programs. A large facility to produce tsetse flies for SIT application in Ethiopia was inaugurated in 2007. To support this project, a Glossina pallidipes colony originating from Ethiopia was successfully established in 1996, but later up to 85% of adult flies displayed symptoms of SGH. As a result, the colony declined and became extinct by 2002. The difficulties experienced with the rearing of G. pallidipes, epitomized by the collapse of the G. pallidipes colony originating from Ethiopia, prompted the urgent need to develop management strategies for the salivary gland hypertrophy virus (SGHV) for this species. As a first step to identify suitable management strategies, the virus isolated from G. pallidipes (GpSGHV) was recently sequenced and research was initiated on virus transmission and pathology. Different approaches to prevent virus replication and its horizontal transmission during blood feeding have been proposed. These include the use of antiviral drugs such as acyclovir and valacyclovir added to the blood for feeding or the use of antibodies against SGHV virion proteins. In addition, preliminary attempts to silence the expression of an essential viral protein using RNA interference will be discussed.

Preliminary survey on tsetse flies and trypanosomosis at grazing fields and villages in and around the Nech Sar National Park, Southern Ethiopia

Preliminary survey on tsetse flies and trypanosomosis were conducted between July and August 2007 at grazing fields and villages in and around the Nech Sar national park, with the ultimate intention of forwarding baseline information on the extent of the problem and possible control strategies. . Entomological (Tsetse flies) survey was conducted by deploying a total of 16 geo referenced NGU traps on the grazing fields of cattle. Parasitological (Trypanosomosis) survey and PCV (Packed Cell Volume) measurement were done on randomly selected 202 cattle, of the park neighboring villagers. Glossina pallidipes with mean apparent density of 11.46 ftd (flies per trap per day) were found to be the only prevailing tsetse fly species in the study area. However, the mean apparent density of biting flies was found to be 4.54 ftd. Trypanosomosis with population mean estimated 17.33±5.30 were seen to be a serious problem of cattle in the area. Trypanosoma congolense and T. vivax were the two dominant species encountered in the area. However statistically significant proportion of the cattle (P

A Survey for Biting Flies in three Local Government Areas of Taraba State, Nigeria

This study was carried out to determine the prevalence of biting flies from Gashaka, Ibi and Karim Lamido Local Government Areas (LGA) of Taraba State between July and August, 2010 using biconical traps, and identify them using morphological characteristics. Of the 908 biting flies collected from the traps 37.9% (344/908) were Tabanus, 25.9% (235/908) were Haematopota, 24.5% (223/908) were Chrysops, and 11.7% (106/908) were Glossina. Based on the LGAs sampled, the distribution of the flies in Gashaka, Ibi, and Karim Lamido (K/Lamido) were 44.6% (419/908), 21.9% (199/908), and 33.5% (290/908) respectively (p<0.05). An infection rate of 1.89% (2/106) was observed among the tsetse flies trapped. Two species of tsetse flies were identified as Glossina palpalis representing 67.9% (72/106) and Glossina tachinoides 32.1% (34/106). In conclusion, Tabanids had the highest distribution while Glossina had the lowest distribution across the three (3) LGAs of the State.

Evolutionary genomics of Glossina morsitans immune-related CLIP domain serine proteases and serine protease inhibitors

Several species of haematophagous tsetse flies (genus Glossina) are vectors for trypanosomes, the parasitic protozoans that cause Human African Trypanosomiasis (HAT). Although there was a reduced incidence of HAT in the mid 1960s, decreased disease surveillance has led to a resurgence of HAT in sub-Saharan Africa. Despite being efficient vectors for HAT transmission, the prevalence of G. morsitans infection by trypanosomes in the wild is surprisingly minimal. The precise mechanisms by which G. morsitans remain refractory to trypanosome infection are largely unknown although it has been demonstrated that G. morsitans mounts a strong immune response to invading pathogens. This study identifies G. morsitans immune-related CLIP domain serine proteases and their inhibitors, serine protease inhibitors (serpin) genes. It further establishes their evolutionary relationships with counterparts in Drosophila melanogaster, Anopheles gambiae, Bombyx mori, Manduca sexta and Culex quinquefasciatus. Multiple sequence alignments show conservation of most secondary structure elements for both CLIPs and serpins. Amino acid composition of the serpin reactive site loop (RSL) indicates that the G. morsitans serpins act through an inhibitory mechanism to the target serine protease. Similar to D. melanogaster and unlike A. gambiae, the transcriptome data suggest that G. morsitans does not contain gene expansions in their CLIP-domain serine protease and serpin families. The presence of alternatively spliced variants in the G. morsitans serpins transcriptome data mirrors that of the D. melanogaster transcriptome.

Universal primers for rapid detection of hytrosaviruses

Hytrosaviridae is a proposed virus family encompassing viruses that cause salivary gland hypertrophy (SGH) syndrome in infected insects and reduce the fertility in their dipteran insect hosts. They contain a large, double stranded DNA genome of 120–190 kbp. To date, these viruses have been detected only in adult Diptera. These include hytrosaviruses detected in various tsetse fly species ( Glossina spp.), the narcissus bulb fly Merodon equestris and the house fly Musca domestica. The limited number of hytrosaviruses reported to date may be a reflection of the frequent absence of external symptoms in infected adult flies and the fact that the virus does not cause rapid mortality. Based on the complete genome sequence of Glossinia pallidipes (GpSGHV) and Musca domestica (MdSGHV) salivary gland hypertrophy viruses, a PCR based methodology was developed to detect the viruses in these species. To be able to detect hytrosaviruses in other Diptera, five degenerate primer pairs were designed and tested on GpSGHV and MdSGHV DNA using gradient PCR with annealing temperatures from 37 to 61 °C. Two pairs of primers were selected from p74, two pairs from PIF-1 and one pair from ODV-e66 homologous proteins. Four primer pairs generated a virus specific PCR product on both MdSGHV and GpSGHV at all tested annealing temperatures, while the ODV-e66 based primers did not generate a virus specific product with annealing temperatures higher that 47 °C. No non-specific PCR product was found when using genomic DNA of infected flies as template DNA. These results offer new sets of primers that could be used to detect hytrosaviruses in other insects.

Proteomic analysis of Glossina pallidipes salivary gland hypertrophy virus virions for immune intervention in tsetse fly colonies

Many species of tsetse flies (Diptera: Glossinidae) can be infected by a virus that causes salivary gland hypertrophy (SGH). The genomes of viruses isolated from Glossina pallidipes (GpSGHV) and Musca domestica (MdSGHV) have recently been sequenced. Tsetse flies with SGH have reduced fecundity and fertility which cause a serious problem for mass rearing in the frame of sterile insect technique (SIT) programmes to control and eradicate tsetse populations in the wild. A potential intervention strategy to mitigate viral infections in fly colonies is neutralizing of the GpSGHV infection with specific antibodies against virion proteins. Two major GpSGHV virion proteins of about 130 and 50&emsp14;kDa, respectively, were identified by Western analysis using a polyclonal rabbit antibody raised against whole GpSHGV virions. The proteome of GpSGHV, containing the antigens responsible for the immune-response, was investigated by liquid chromatography tandem mass spectrometry and 61 virion proteins were identified by comparison with the genome sequence. Specific antibodies were produced in rabbits against seven candidate proteins, including the ORF10/C-terminal fragment, ORF47 and ORF96 as well as proteins involved in peroral infectivity PIF-1 (ORF102), PIF-2 (ORF53), PIF-3 (ORF76) and P74 (ORF1). Antiserum against ORF10 specifically reacted to the 130&emsp14;kDa protein in a Western blot analysis and to the envelope protein of GpSGHV, detected by using immunogold-electron microscopy. This result suggests that immune intervention of viral infections in colonies of G. pallidipes is a realistic option.

Bovine trypanosomosis and its vectors in two districts of Bench Maji zone, South Western Ethiopia

A cross-sectional study was carried out from November 2008 to February 2009 in Guraferda and Sheko districts of Bench Maji Zone, South Western Ethiopia. The objective of the study was to determine the prevalence of bovine trypanosomosis and the density of its vectors. An overall prevalence of trypanosome infection in the study area was 4.4%. Trypanosoma congolense (36.36%) was the dominant trypanosome species followed by Trypanosoma vivax (18.18%) and Trypanosoma brucei (9.09%). Mean packed cell volume value of parasitemic animals (21.8%) was significantly (P<0.05) lower than that of aparasitemic animals (27.7%). Biconical and NGU traps were deployed for 72 h, and the result indicated Glossina pallidipes followed by Glossina fuscipes as the only tsetse fly species caught in the study area along with other biting flies like Stomoxys and Tabanus. The apparent density of tsetse flies was 2.83 flies trap(-1) day(-1). NGU trap caught more of G. pallidipes while biconical trap caught more G. fuscipes, and the difference was significant (P<0.05). Although the current study indicated low prevalence of trypanosomosis in the study area, the impacts of trypanosomosis on cattle production and productivity should not be neglected. Therefore, attention should be given to control the disease and also the vector.

Dynamics of the salivary gland hypertrophy virus in laboratory colonies of Glossina pallidipes (Diptera: Glossinidae)

Many species of tsetse flies are infected by a virus that causes salivary gland hypertrophy (SGH) and the virus isolated from Glossina pallidipes (GpSGHV) has recently been sequenced. Flies with SGH have a reduced fecundity and fertility. To better understand the impact of this virus in a laboratory colony of G. pallidipes, where the majority of flies are infected but asymptomatic, and to follow the development of SGH in the offspring of symptomatic infected flies, we examined the progeny of tsetse flies reared under different conditions. The results show that the progeny of asymptomatic parents did not develop SGH, while the progeny of symptomatic female flies mated with asymptomatic males developed a high rate of SGH (65% in male and 100% in females) and these flies were sterile. Stress in the form of high fly density in holding cages (180 flies/cage) and high temperature (30 °C) in the holding room did not affect the prevalence of the SGH. The virus is excreted in the saliva and there is a strong correlation between the infection status (negative, slight or strong by PCR) and the numbers of virus particles released into the blood on which the flies were fed. On average, around 10 2 and 10 7 virus particles were found in the blood after feeding asymptomatic or symptomatic infected flies respectively. Feeding the flies on new blood at every feed for three generations caused a significant reduction in the virus copy number in these flies when compared with the virus copy number in flies fed under the normal feeding regime. The results of these studies allowed the initiation of colony management protocols that aim to minimize the risk of horizontal transmission and to enable the establishment of colonies with a low virus prevalence or possibly even those that are virus free.

Diversity and spatial distribution of vectors and hosts of T. brucei gambiense in forest zones of, Southern Cameroon: Epidemiological implications

Host and vector distribution of Trypanosoma brucei gambiense was studied in relation to habitat types and seasons. Six (19.35%) of the 31 mammal species recorded in Bipindi were reservoir hosts. Cercopithecus nictitans was confined to the undisturbed forest and the low intensive shifting cultivation zones, while Cephalophus monticola, Cephalophus dorsalis, Cricetomys gambianus, Atherurus africanus and Nandinia binotata occurred in all the habitat types. As for vectors of human African trypanosomiasis (HAT), Glossina palpalis palpalis, was the most abundant (99.13%) among tsetse fly species. It occurs in all biotopes with its highest density recorded in the village-adjacent forest. The village-adjacent forest is therefore the most risky transmission zone for HAT mainly during the short rainy season when G. palpalis palpalis' density is highest (2.91); while, the high and low intensive shifting cultivation zones are the most important contact zones between humans, G. palpalis palpalis and wild mammals in all seasons.

Chorologie et infection par les trypanosomes deGlossina palpalis palpalisdans la forêt du banco et ses reliques, abidjan (Côte d’ivoire)

In order to implement an anti-vector programme in the suburb of Abidjan (Côte d'Ivoire), investigations were conducted to assess the tsetse fly densities as well as infection with trypanosomes. Catches were carried out during the rainy season and dry season with Vavoua traps laid during four consecutive days in different sites (Banco forest, Abidjan zoological park, area of the University of Abobo-Adjamé). One species of tsetse fly (Glossina polpalis palpalis) and two species of trypanosomes (Trypanosoma congolense, T. vivax) have been revealed. The apparent density per trap per day (DAP) is very high in the zoological park, 54.8 tsetse fly/trap/day during the dry season and 28.1 during the rainy season. At the University of Abobo-Adjamé, the DAP is respectively 13.5 and 8.1 tsetse fly/trap/day during the rainy season, and in the dry season it is only 0.9 and 0.8 in the Banco Forest. The physiological age on all sites is as follows: 57.5 % of old parous, 39% of young parous and 3.6 % of nulliparous in the rainy season. These proportions vary to 51.9% of young porous, 47.1% of old parous and 1% of nulliparous in the dry season. The overall infection rate is estimated at 20.7% in the rainy season and 20% in the dry season. Statistical analysis have showed a significant difference in the distribution of infection rates.

Whose Boundary? An Individual Species Perspectival Approach to Borders

Understanding ecological boundaries is recognized by ecologists as important for understanding ecosystem dynamics. All borders are borders in relation to some organism. However, much of the literature on habitat change ignores this basic ecological fact. In addition, borders are highly influenced by accidental or historical features of ecosystems, and researchers have in many cases defined them only in terms of convenience. Several viewpoints explored in this article reflect this skepticism about identifying ecosystems as real structured entities. I draw on Ghiselin’s (1974) hypothesis that species are not natural kinds but individuals, to develop a relational approach to ecological boundaries. I argue that with regard to ecology a border is always a border for a specific organism, and is a border in a specific manner for that organism. I draw on studies of two species of tsetse fly found in the Mauhoun river basin in Burkina Faso to illustrate why this relational approach is important. This approach may also help identify weaknesses in conservation efforts that have not properly asked the question, “Boundary for what?”

Olfactory and behavioural responses of tsetse flies, Glossina spp., to rumen metabolites

Herbivores provide tsetse flies with a blood meal, and both wild and domesticated ruminants dominate as hosts. As volatile metabolites from the rumen are regularly eructed with rumen gas, these products could serve tsetse flies during host searching. To test this, we first established that the odour of rumen fluid is attractive to hungry Glossina pallidipes in a wind tunnel. We then made antennogram recordings from three tsetse species (G. pallidipes morsitans group, G. fuscipes palpalis group and G. brevipalpis fusca group) coupled to gas chromatographic analysis of rumen fluid odour and of its acidic, mildly acidic and neutral fractions. This shows tsetse flies can detect terpenes, ketones, carboxylic acids, aliphatic aldehydes, sulphides, phenols and indoles from this biological substrate. A mixture of carboxylic acids at a ratio similar to that present in rumen fluid induced behavioural responses from G. pallidipes in the wind tunnel that were moderately better than the solvent control. The similarities in the sensory responses of the tsetse fly species to metabolites from ruminants demonstrated in this study testify to a contribution of habitat exploitation by these vertebrates in the Africa-wide distribution of tsetse.

Population sizes and dispersal pattern of tsetse flies: rolling on the river?

The West African trypanosomoses are mostly transmitted by riverine species of tsetse fly. In this study, we estimate the dispersal and population size of tsetse populations located along the Mouhoun river in Burkina Faso where tsetse habitats are experiencing increasing fragmentation caused by human encroachment. Dispersal estimated through direct (mark and recapture) and indirect (genetic isolation by distance) methods appeared consistent with one another. In these fragmented landscapes, tsetse flies displayed localized, small subpopulations with relatively short effective dispersal. We discuss how such information is crucial for designing optimal strategies for eliminating this threat. To estimate ecological parameters of wild animal populations, the genetic measures are both a cost- and time-effective alternative to mark-release-recapture. They can be applied to other vector-borne diseases of medical and/or economic importance.

Control of bovine trypanosomosis by restricted application of insecticides to cattle using footbaths

African animal trypanosomoses are the main parasitological constraints to livestock production in many sub-Saharan African countries infested with tsetse flies. A prospective survey was implemented in Dafinso (Burkina Faso) to assess the effect of deltamethrin 0.005% (Vectocid ND, CEVA Santé Animale) impregnation of cattle on trypanosomes transmission in cattle. Two herds were involved in the survey. They were watered at two different waterpoints located on the same river harboring a Guinean riparian forest infested with two different species of tsetse flies (Diptera: Glossinidae), Glossina palpalis gambiensis Vanderplank and G. tachinoides Westwood. Animals belonging to one of the herds were impregnated with deltamethrin applied with a footbath whereas the other herd was used as control. The overall incidence of cattle trypanosomoses was reduced ( p = 0.01) from 0.76 (control group) to 0.11 (footbath-treated group). A positive effect of the footbath treatment on packed-cell volume was observed ( p < 0.001). The conditions requested to use a footbath to prevent cattle trypanosomoses are discussed.