College of Veterinary and Medical Sciences

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Browsing College of Veterinary and Medical Sciences by Subject "Abundance"

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    Bionomics, blood-host plasticity and its effect on host-choice and feeding behaviour of tsetse species from selected human- wildlife interface in Tanzania
    (Sokoine University of Agriculture, 2024-04) Mdee, Filbert Ewald
    Tsetse flies are vectors of trypanosome parasites which cause human African trypanosomiasis (HAT) in human and African animal trypanosomiasis (AAT) in livestock across Sub-Saharan Africa. These flies feed exclusively on animals’ blood. It is during blood- feeding process of these flies; un-infected host get infected by parasites carried by infected vector. Several tsetse controls programs have been implemented so as to minimize the incidences of trypanosome infections; however, the human-wildlife interfaces remain as the risk areas where both livestock and human being can be infected with trypanosome parasites. Therefore, surveillance and control of these flies is important so as to minimize the African trypanosomiasis’ risks in these areas. This study assessed the species composition, abundance and phylogenetic relatedness of wild collected tsetse flies from selected human-wildlife-livestock interface in Tanzania. Variation in host choice and feeding behaviours of predominant species’ (Glossina morsitans) siblings whose parents were blood-fed on different host species were also investigated. The tsetse flies were trapped seasonally in two selected wards within Morogoro Rural district. The study wards and villages were purposively selected targeting those which are bordering to protected areas. In each ward, baited NZI, Pyramidal and Biconical traps were deployed at 200m distance apart from each other for 72 hours before rotating to the next trapping sites. Trapped flies were collected from the traps after 24 hours then identified morphologically and later confirmed using the Polymerase Chain Reaction (PCR). Moreover, a colony of tsetse flies were established from pupa obtained from tsetse and vector control centre, Tanga. Hatched flies were maintained on selected hosts blood until the offsprings were obtained for the experiments. The host-choice and feeding behaviours experiments were carried out in large semi-field cage containing four small equal size screen cages. During the experiments, individual host was placed in a screen cage which allowed flies to enter through openings on each side. The groups of flies (20 per replicate) colour-marked differently basing on their parents’ bloodmeal hosts, were released from the centre of large semi-field cage and left to forage for 24 hours before being collected, then, sorted basing on the location, feeding status and parents’ bloodmeal. The total of 784 tsetseflies were collected; Glossina pallidipes (n=371; 47.32%) and Glossina morsitans morsitans (n=413; 52.68%). Of these, 96 flies (80-female, 16-male) were blood-fed; 57(48-female and 9-male) G. pallidipes and 39(32- female, 7-male) G.m. morsitans. Overall abundance of collected tsetse significantly varied across surveyed wards (χ2=4.597, df=1, p= 0.032), villages (χ2=9.491, df=3, p= 0.023), habitats (χ2=17.239, df=2, p<0.001), months (χ2=13.507, df=3, p= 0.004) and deployed traps (χ2=6.348, df= 2, p= 0.04). About 78.82% of tsetse flies were collected from Kisaki ward (n=618; p<0.001) and 21.17% (n=166; p=0.032) from Bwakila chini. The highest proportion of these flies were collected in Mbojoge village (62%; n= 489) followed by Kiperege (18%; n=141) and Sebo (16%; n=129). NZI traps collected the highest proportion of tsetse flies (n=422; 54%; 4.98 FTD) followed by Pyramidal traps (n=281; 36%; 4.01 FTD) and Biconical traps (n=81; 10%; 1.87 FTD). Similarly, the large proportion of tsetse flies (78.06%) were collected in bushed grassland habitat (n=612; 55.41 FTD) followed by woodland habitat (16.45%; n=129; 20.56 FTD) and farmland (5.5%; n=43; 7.17 FTD). The phylogenetic analysis revealed genetic relatedness of tsetse flies collected in Tanzania with those collected from Nigeria and Senegal. Furthermore, a total of 213 flies (72.95% of the recovered) were attracted to the hosts. The number of flies attracted to different hosts varied significantly (χ24= 33.685, p= 0.0001); Rodent (n=80, p=0.006), Rabbit (n=59, p=0.331), Guinea pig (n=49, p=0.057) and squirrel (n=25, p=0.005). The number of flies attracted to their parent’s blood meal source varied significantly (χ212 = 56.476, p<0.001); rabbits (n= 35, 59.32%, p<0.001), rodent (n=25, 31.25%, p=0.043) and guinea pig (n= 19, 38.78%, p=0.45). But, only 39 flies (18.31% of total attracted) bloodfed on the hosts; Guinea pigs (n=10, 25.64%), Rodents (n=23, 58.97%), Rabbits (n=6, 15.38%) and Squirrels (n=0,0.0%). There was significant variation in number of flies that fed successively across hosts (χ24=49.478, p<0.001). The present study recommends NZI and Pyramidal traps for tsetse fly control at the interface and wet season as appropriate season for conducting control activities. Also, the study confirms the presence of the hosts’ differential attractiveness to flies but failed to explain observed behaviours in relation to genetic inheritance. Therefore, future studies are recommended to investigate the effect of bloodmeal sources on tsetse fly siblings’ behaviours across filial generations using small mammals.
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    Molecular detection of arboviruses in yellow fever mosquitoes collected from Kyela district, Tanzania
    (ResearchGate, 2016-10) Bisimwa, N.P; Angwenyi, S; Kinimi, E; Shayo, M; Bwihangane, B.A; Kasanga, C.J
    Arboviruses belong to a group of viruses that are transmitted by arthropods, mainly mosquitoes and ticks causing clinical disease symptoms in humans and animals ranging from febrile illnesses to hemorrhagic fevers. The present study aimed at examining the circulation of Chikungunya, Dengue, Yellow fever and Rift valley fever viral genomes in Aedes mosquitoes from Kyela district in Tanzania. A systematic vector surveillance spanning two months and covering five sites in Kyela district was carried out in order to evaluate the potential role of Aedes spp. in arbovirus transmission in the study area. Mosquitoes were collected, identified to species level by using morphological keys, pooled in respect species and collection sites and screened for arboviruses by RT-PCR. Adult mosquitoes were collected from April to May, 2015 using CO 2 -baited CDC light traps, magnet traps as well as human landing collection (HLC). The study sites included Kyela town, Kajunjumele, Ipida, Matema and Njisi villages. A total of 480 blood-feed Aedes ssp. were collected, identified and grouped into 24 pools (1- 20 mosquitoes per pool) according to species level and location. Out of the 480 Aedes spp. collected, Aedes aegyptir epresented the most abundant species totaling 338 (70.4%), followed by Aedes africanus 102 (21.2%) and Aedes natalensis being the minority, 40 (8.3%). Arboviruses were detected in nine pools (37.5%) including Alpha viruses (8 pools) and Flavi viruses (1 pool). No sample was positive for Bunya viruses.Chikungunya virus (CHIKV) was detected in 6 (75%) alpha virus positive pools that were collected mostly in the areas where rice cultivation was common. The findings of this study suggest that inhabitants in this region are highly likely to be exposed to arbovirus infections which may represent significant public health concerns.