Age determination for female tsetse flies and the age compositions of samples ofGlossina pallidipesAust.,G. palpalis fuscipesNewst. andG. brevipalpisNewst.

The age compositions of samples of females ofGlossina pallidipesAust.,G. palpalis fuscipesNewst. andG. brevipalpisNewst., are analysed by means of a method of age determination based upon the changes occurring in the reproductive system during successive gonotrophic cycles. This method of age determination is described in detail.Females were sampled by three main methods: in traps, by catching on a bait-animal, and on a fly-round. Some flies were also found as resting flies in the undergrowth.Trap-caught samples ofG. pallidipeswere older (i.e.), contained a larger proportion of old flies (and a smaller proportion of young flies) than the hand-caught samples. The bait-caught samples were intermediate in age structure. Correlated with the increasing mean age in the hand-caught—bait-caught—trap-caught series was an increase in the proportion of females carrying third-instar larvae and a decrease in the proportion of those carrying eggs. Results with samples ofG. palpalis fuscipesandG. brevipalpiswere not so well defined.The results of dissecting teneral and non-teneral nullipars ofG. pallidipesandG. palpalis fuscipesindicate that females of the latter are inseminated some time before they take their first blood-meal, but teneral females ofG. pallidipesare inseminated when they come to the host to feed or after they have fed.The relation of the ovarian method of age determination to Jackson's (1946) wing-fray categories in females ofG. pallidipes, and the probable epidemiological importance of the samples, are also discussed.

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Tsetse blood-meal sources, endosymbionts and trypanosome-associations in the Maasai Mara National Reserve, a wildlife-human-livestock interface

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0008267 ◽

2021 ◽

Vol 15 (1) ◽

pp. e0008267

Author(s):

Edward Edmond Makhulu ◽

Jandouwe Villinger ◽

Vincent Owino Adunga ◽

Maamun M. Jeneby ◽

Edwin Murungi Kimathi ◽

...

Keyword(s):

Blood Meal ◽

Glossina Pallidipes ◽

Tsetse Fly ◽

Tsetse Flies ◽

African Buffalo ◽

African Trypanosomiasis ◽

African Trypanosomes ◽

Sodalis Glossinidius ◽

Vertebrate Hosts ◽

Blood Meals

African trypanosomiasis (AT) is a neglected disease of both humans and animals caused by Trypanosoma parasites, which are transmitted by obligate hematophagous tsetse flies (Glossina spp.). Knowledge on tsetse fly vertebrate hosts and the influence of tsetse endosymbionts on trypanosome presence, especially in wildlife-human-livestock interfaces, is limited. We identified tsetse species, their blood-meal sources, and correlations between endosymbionts and trypanosome presence in tsetse flies from the trypanosome-endemic Maasai Mara National Reserve (MMNR) in Kenya. Among 1167 tsetse flies (1136 Glossina pallidipes, 31 Glossina swynnertoni) collected from 10 sampling sites, 28 (2.4%) were positive by PCR for trypanosome DNA, most (17/28) being of Trypanosoma vivax species. Blood-meal analyses based on high-resolution melting analysis of vertebrate cytochrome c oxidase 1 and cytochrome b gene PCR products (n = 354) identified humans as the most common vertebrate host (37%), followed by hippopotamus (29.1%), African buffalo (26.3%), elephant (3.39%), and giraffe (0.84%). Flies positive for trypanosome DNA had fed on hippopotamus and buffalo. Tsetse flies were more likely to be positive for trypanosomes if they had the Sodalis glossinidius endosymbiont (P = 0.0002). These findings point to complex interactions of tsetse flies with trypanosomes, endosymbionts, and diverse vertebrate hosts in wildlife ecosystems such as in the MMNR, which should be considered in control programs. These interactions may contribute to the maintenance of tsetse populations and/or persistent circulation of African trypanosomes. Although the African buffalo is a key reservoir of AT, the higher proportion of hippopotamus blood-meals in flies with trypanosome DNA indicates that other wildlife species may be important in AT transmission. No trypanosomes associated with human disease were identified, but the high proportion of human blood-meals identified are indicative of human African trypanosomiasis risk. Our results add to existing data suggesting that Sodalis endosymbionts are associated with increased trypanosome presence in tsetse flies.

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Tsetse blood-meal sources, endosymbionts, and trypanosome infections provide insight into African trypanosomiasis transmission in the Maasai Mara National Reserve, a wildlife-human-livestock interface

10.1101/2020.04.06.027367 ◽

2020 ◽

Cited By ~ 1

Author(s):

Edward Edmond Makhulu ◽

Jandouwe Villinger ◽

Vincent Owino Adunga ◽

Maamun M. Jeneby ◽

Edwin Murungi Kimathi ◽

...

Keyword(s):

Blood Meal ◽

Vector Competence ◽

Glossina Pallidipes ◽

Tsetse Fly ◽

Tsetse Flies ◽

African Buffalo ◽

African Trypanosomiasis ◽

Trypanosome Infection ◽

African Trypanosomes ◽

Blood Meals

AbstractBackgroundAfrican trypanosomiasis (AT) is a neglected disease of both humans and animals caused by Trypanosoma parasites, which are transmitted by obligate hematophagous tsetse flies (Glossina spp.). Understanding of AT transmission is hampered by limited knowledge on interactions of tsetse flies with their vertebrate hosts and the influence of endosymbionts on vector competence, especially in wildlife-human-livestock interfaces. We identified the tsetse species, their blood-meal sources, and the correlation between endosymbiont and trypanosome infection status in the trypanosome-endemic Maasai Mara National Reserve (MMNR) of Kenya.Methodology/Principal FindingsAmong 1167 tsetse flies (1136 Glossina pallidipes, 31 Glossina swynnertoni) collected from 10 sampling sites, 28 (2.4%) were positive by PCR for trypanosomes, majority (17/28) being Trypanosoma vivax. Blood-meal analyses based on high-resolution melting analysis of mitochondrial cytochrome c oxidase 1 and cytochrome b gene PCR products (n = 345) identified humans as the most common vertebrate host (37%), followed by hippopotamus (29.1%), African buffalo (26.3%), elephant (3.39%), and giraffe (0.84%). Trypanosome-infected flies had fed on hippopotamus and buffalo. Additionally, PCR analysis revealed that tsetse flies were more likely to be infected with trypanosomes if they were infected with the Sodalis glossinidius endosymbiont (P = 0.0022 Fisher’s exact test).Conclusions/SignificanceDiverse species of wildlife hosts may contribute to the maintenance of tsetse populations and/or persistent circulation of African trypanosomes in the MMNR. Although the African buffalo is known to be a key reservoir of AT, the higher proportion of hippopotamus blood-meals in trypanosomes-infected flies identified here indicates that other wildlife species may also be important to transmission cycles. No trypanosomes associated with human disease were identified, but the high proportion of human blood-meals identified are indicative of human African trypanosomiasis transmission risk. Furthermore, this work provides data showing that Sodalis endosymbionts can is associated with increased trypanosome infection rates in endemic ecologies.Author summaryHuman and animal African trypanosomiasis are neglected tropical diseases with potential to spread to new areas. Wild animals are important reservoirs for African trypanosomes and crucial in the emergence and re-emergence of AT. Vertebrate host-vector-parasite interactions are integral to trypanosome transmission. We investigated the vertebrate blood-meals and trypanosomes-endosymbionts co-infections in tsetse flies, which have been associated with reservoirs and vector competence, respectively, on AT transmission in Kenya’s Maasai Mara National Reserve. We identified tsetse fly diversity, trypanosome and endosymbiont infection status, and vertebrate blood-meal hosts to infer potential transmission dynamics. We found that Glossina pallidipes was the major tsetse fly vector and that Trypanosoma vivax was the main trypanosome species circulating in the region. Humans, hippopotamus, and buffalo were the most frequented for blood-meals. Buffalo and hippopotamus blood-meals were identified in trypanosome infected flies. Feeding of the flies on both humans and wildlife may potentiate the risk of the human trypanosomiasis in this ecology. Additionally, we found that the endosymbiont Sodalis glossinidius is associated with higher trypanosome infection rates in wild tsetse flies. These findings emphasize the importance of understanding the interaction of tsetse flies with vertebrate blood-meal sources and their endosymbionts in the transmission and control of AT.

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An update on the distribution of Glossina (tsetse flies) at the wildlife-human-livestock interface of Akagera National Park, Rwanda

Parasites & Vectors ◽

10.1186/s13071-021-04786-3 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Richard S. Gashururu ◽

Samuel M. Githigia ◽

Methode N. Gasana ◽

Richard Habimana ◽

Ndichu Maingi ◽

...

Keyword(s):

National Park ◽

Control Strategies ◽

Glossina Pallidipes ◽

Distribution Patterns ◽

Tsetse Flies ◽

Wet Season ◽

Chi Square ◽

Large Numbers ◽

Surrounding Areas ◽

Biconical Traps

Abstract Background Glossina (tsetse flies) biologically transmit trypanosomes that infect both humans and animals. Knowledge of their distribution patterns is a key element to better understand the transmission dynamics of trypanosomosis. Tsetse distribution in Rwanda has not been well enough documented, and little is known on their current distribution. This study determined the current spatial distribution, abundance, diversity, and seasonal variations of tsetse flies in and around the Akagera National Park. Methods A longitudinal stratified sampling following the seasons was used. Biconical traps were deployed in 55 sites for 6 consecutive days of each study month from May 2018 to June 2019 and emptied every 48 h. Flies were identified using FAO keys, and the number of flies per trap day (FTD) was used to determine the apparent density. Pearson chi-square (χ2) and parametrical tests (t-test and ANOVA) were used to determine the variations between the variables. The significance (p < 0.05) at 95% confidence interval was considered. Logistic regression was used to determine the association between tsetse occurrence and the associated predictors. Results A total of 39,516 tsetse flies were collected, of which 73.4 and 26.6% were from inside Akagera NP and the interface area, respectively. Female flies accounted for 61.3 while 38.7% were males. Two species were identified, i.e. G. pallidipes [n = 29,121, 7.4 flies/trap/day (FTD)] and G. morsitans centralis (n = 10,395; 2.6 FTD). The statistical difference in numbers was significant between the two species (p = 0.000). The flies were more abundant during the wet season (15.8 FTD) than the dry season (4.2 FTD). Large numbers of flies were trapped around the swamp areas (69.1 FTD) inside the park and in Nyagatare District (11.2 FTD) at the interface. Glossina morsitans was 0.218 times less likely to occur outside the park. The chance of co-existing between the two species reduced outside the protected area (0.021 times). Conclusions The occurrence of Glossina seems to be limited to the protected Akagera NP and a narrow band of its surrounding areas. This finding will be crucial to design appropriate control strategies. Glossina pallidipes was found in higher numbers and therefore is conceivably the most important vector of trypanosomosis. Regional coordinated control and regular monitoring of Glossina distribution are recommended. Graphic Abstract

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Comparative performance of traps in catching tsetse flies (Diptera: Glossinidae) in Tanzania

Onderstepoort Journal of Veterinary Research ◽

10.4102/ojvr.v83i1.1057 ◽

2016 ◽

Vol 83 (1) ◽

Cited By ~ 5

Author(s):

Imna I. Malele ◽

Johnson O. Ouma ◽

Hamisi S. Nyingilili ◽

Winston A. Kitwika ◽

Deusdedit J. Malulu ◽

...

Keyword(s):

Glossina Pallidipes ◽

Abundant Species ◽

Tsetse Fly ◽

Tsetse Flies ◽

Comparative Performance ◽

Control Programmes ◽

Fly Control ◽

Tsetse Fly Control ◽

Species Being ◽

Biconical Traps

This study was conducted to determine the efficiency of different tsetse traps in 28 sites across Tanzania. The traps used were biconical, H, NGU, NZI, pyramidal, S3, mobile, and sticky panels. Stationary traps were deployed at a distance of 200 m apart and examined 72 h after deployment. The results showed that 117 (52.2%) out of the 224 traps deployed captured at least one Glossina species. A total of five Glossina species were captured, namely Glossina brevipalpis, Glossina pallidipes, Glossina swynnertoni, Glossina morsitans, and Glossina fuscipes martinii. Biconical traps caught tsetse flies in 27 sites, pyramidal in 26, sticky panel in 20, mobile in 19, S3 in 15, NGU in 7, H in 2 and NZI in 1. A total of 21 107 tsetse flies were trapped, with the most abundant species being G. swynnertoni (55.9%), followed by G. pallidipes (31.1%), G. fuscipes martinii (6.9%) and G. morsitans (6.0%). The least caught was G. brevipalpis (0.2%). The highest number of flies were caught by NGU traps (32.5%), followed by sticky panel (16%), mobile (15.4%), pyramidal (13.0%), biconical (11.3%) and S3 (10.2%). NZI traps managed to catch 0.9% of the total flies and H traps 0.7%. From this study, it can be concluded that the most efficient trap was NGU, followed by sticky panel and mobile, in that order. Therefore, for tsetse fly control programmes, NGU traps could be the better choice. Conversely, of the stationary traps, pyramidal and biconical traps captured tsetse flies in the majority of sites, covering all three ecosystems better than any other traps; therefore, they would be suitable for scouting for tsetse infestation in any given area, thus sparing the costs of making traps for each specific Glossina species.Keywords: tseste; traps; densties; Glossina; mobile; stationary; Tanzania

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Aircraft Applications of Insecticides in East Africa. VI.—Applications of a coarse Aerosol containning DDT to control the Tsetse Flies, Glossina morsitans Westw., Glossina swynnertoni Aust. and Glossina pallidipes Aust.

Bulletin of Entomological Research ◽

10.1017/s0007485300029655 ◽

1954 ◽

Vol 45 (3) ◽

pp. 585-603 ◽

Cited By ~ 11

Author(s):

K. S. Hocking ◽

D. Yeo ◽

D. G. Anstey

Keyword(s):

Random Effects ◽

Glossina Pallidipes ◽

Tsetse Flies ◽

Glossina Morsitans ◽

Median Diameter ◽

Coarse Aerosol ◽

Savannah Woodland ◽

Mass Median ◽

Glossina Swynnertoni ◽

Mass Median Diameter

An experiment is described where applications of a coarse aerosol were made to savannah woodland containing the tsetse flies, Glossina moritans Westw., G. swynnertoni Aust. and G. pallidipes Aust.Seven applications were made, each at a nominal dosage of 0·25 lb. of technical DDT per acre and 0·25 gallons of solution per acre. The applications in any particular part of the treaed woodland covered an interval of 90 days, or rather more than two pupal periods.The coarse aerosol was produced by emitting the insecticidal solution under pressure through fine nozzles fitted to a boom. It had a mass median diameter of approximately 60 microns, and droplet dismeters varied from a few microns to approximately 200 microns.The population of G. pallidipes was so drastically reduced that it has subsequently dies out. The reduction of G. morsitans was approximately 95 per cent. The differences between the reductions are attributed mainly to differences between the ease with which the three species can be killed. It is pointed out that this is not necessarily equivalent to differences in susceptibility.Comparisons are made with previous experiments, and the different results of the various experiments are difficult to explian satisfactory. The increased cover in savannah areas during the leafy period may have reduced the effectiveness of the applications, and the total periods covered by the various series of applications were probably also important. Random effects, leading to ineffective treatments, may also be important.Costs are discussed.

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Differential virulence and tsetse fly transmissibility of Trypanosoma congolense and Trypanosoma brucei strains

Onderstepoort Journal of Veterinary Research ◽

10.4102/ojvr.v84i1.1412 ◽

2017 ◽

Vol 84 (1) ◽

Cited By ~ 2

Author(s):

Purity K. Gitonga ◽

Kariuki Ndung’u ◽

Grace A. Murilla ◽

Paul C. Thande ◽

Florence N. Wamwiri ◽

...

Keyword(s):

Survival Time ◽

Trypanosoma Brucei ◽

Acute Infection ◽

Glossina Pallidipes ◽

Trypanosoma Congolense ◽

Tsetse Fly ◽

Economic Losses ◽

Entire Group ◽

Tsetse Flies ◽

African Countries

African animal trypanosomiasis causes significant economic losses in sub-Saharan African countries because of livestock mortalities and reduced productivity. Trypanosomes, the causative agents, are transmitted by tsetse flies (Glossina spp.). In the current study, we compared and contrasted the virulence characteristics of five Trypanosoma congolense and Trypanosoma brucei isolates using groups of Swiss white mice (n = 6). We further determined the vectorial capacity of Glossina pallidipes, for each of the trypanosome isolates. Results showed that the overall pre-patent (PP) periods were 8.4 ± 0.9 (range, 4–11) and 4.5 ± 0.2 (range, 4–6) for T. congolense and T. brucei isolates, respectively (p < 0.01). Despite the longer mean PP, T. congolense–infected mice exhibited a significantly (p < 0.05) shorter survival time than T. brucei–infected mice, indicating greater virulence. Differences were also noted among the individual isolates with T. congolense KETRI 2909 causing the most acute infection of the entire group with a mean ± standard error survival time of 9 ± 2.1 days. Survival time of infected tsetse flies and the proportion with mature infections at 30 days post-exposure to the infective blood meals varied among isolates, with subacute infection–causing T. congolense EATRO 1829 and chronic infection–causing T. brucei EATRO 2267 isolates showing the highest mature infection rates of 38.5% and 23.1%, respectively. Therefore, our study provides further evidence of occurrence of differences in virulence and transmissibility of eastern African trypanosome strains and has identified two, T. congolense EATRO 1829 and T. brucei EATRO 2267, as suitable for tsetse infectivity and transmissibility experiments.

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Does cuticular elasticity regulate the size of the blood meal imbibed by female Glossina austeni?

Canadian Journal of Zoology ◽

10.1139/z83-244 ◽

1983 ◽

Vol 61 (8) ◽

pp. 1888-1891 ◽

Cited By ~ 5

Author(s):

C. B. Carruthers ◽

K. G. Davey

Keyword(s):

Direct Measurement ◽

Blood Meal ◽

Meal Size ◽

Tsetse Flies ◽

Glossina Austeni ◽

Before And After

In tsetse flies, a larva grows to maturity inside the uterus of the female. The size of the blood meal imbibed by females is known to increase at ovulation and decrease as the larva gets larger, so that the total volume of the fly remains constant. This has led to the hypothesis that meal size is determined by cuticular elasticity. Direct measurement of the elasticity of abdominal cuticle in mated females, before and after ovulation, and in virgin females, which do not ovulate, demonstrates that cuticular elasticity is unrelated to ovulation. Further, meal size is not closely correlated with cuticular elasticity. The hypothesis is therefore rejected.

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