Browsing by Author "Mataba, Gordian"

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Culex quinquefasciatus mosquito avoids ovipositing in habitats with the annual fish (Nothobranchius neumanni) in Tanzania
(Springer Netherlands, 2024-05-03) Mataba, Gordian; Munishi, Linus; Brendonck, Luc; Vanschoenwinkel, Bram
Mosquitoes are known to choose oviposition habitats actively based on their suitability for survival of their offspring. They thus avoid laying eggs in dangerous habitats with aquatic predators through detection of their cues. Visual, tactile, and chemical cues emitted by certain predators have been shown to reduce oviposition in some mosquitoes, which in turn may affect their adult population sizes. However, those tests tend to be limited to species from temperate regions. Moreover, mosquito oviposition response to predator cues have been shown to be predator specific, but this has not been investigated for many potential predators worldwide. In the African subtropics, temporary ponds can be important mosquito breeding habitats and the same habitats are also used by a group of specialized killifish that can survive dry periods using drought resistant eggs. Although they are reported as mosquito predators, it is unknown whether mosquitoes actively avoid laying eggs in ponds with annual killifish. We investigated this using the mosquito Culex quinquefasciatus and the free and caged killifish Nothobranchius neumanni in the outdoor mesocosm experiments in Tanzania. We found that Cx. quinquefasciatus had 71% lower oviposition in mesocosms with free swimming killifish and 68% lower oviposition in mesocosms with caged killifish. We conclude that predator-released chemical cues alone are enough to explain the observed responses. If the cues can be isolated and chemically identified can be developed into a biological mosquito control strategy and used to safeguard public health in areas where mosquito borne diseases are endemic.
Fish predation affects invertebrate community structure of tropical temporary ponds, with downstream effects on phytoplankton that are obscured by pesticide pollution
(Elsevier Ltd., 2024-02-14) Kafula, Yusuph; Mataba, Gordian; Mwaijengo, Grite; Moyo, Francis; Munishi, Linus; Vanschoenwinkel, Bram; Brendonck, Luc; Thoré, Eli
Aquatic biota of tropical temporary ponds typically experience a wide range of stressors that can drive the structure and dynamics of natural communities. Particularly in regions with intense agricultural activity, aquatic biota may not only experience predation pressure but also stress from pesticides that inadvertently enter the ponds. We increasingly understand how these different sources of stress affect classic model taxa under controlled laboratory conditions, but how predators and pesticides may jointly affect pond invertebrate communities is still unclear, particularly for tropical systems. Here, we conducted an outdoor mesocosm experiment to study how fish predation combined with exposure to an environmentally relevant concentration of the commonly used insecticide cypermethrin (0.8 ng/L) affects the structure of invertebrate communities, and its potential effects on leaf litter decomposition and invertebrate grazing efficiency as measures of ecosystem functioning. A total of seven invertebrate taxa were recorded in the mesocosm communities. Fish predation effectively lowered the number of invertebrate taxa, with fish mesocosms being dominated by high densities of rotifers, associated with lower phytoplankton levels, but only when communities were not simultaneously exposed to cypermethrin. In contrast, cypermethrin exposure did not affect invertebrate community structure, and neither fish predation nor cypermethrin exposure affected our measures of ecosystem functioning. These findings suggest that predation by killifish can strongly affect invertebrate community structure of tropical temporary ponds, and that downstream effects on phytoplankton biomass can be mediated by exposure to cypermethrin. More broadly, we contend that a deeper understanding of (tropical) temporary pond ecology is necessary to effectively manage these increasingly polluted systems.
Impact of anthropogenic pollution and artisanal fishing on the population of Tilapia spp. Oreochromis niloticus and Oreochromis amphimelas in Lake Manyara, northern Tanzania
(Springer Nature B.V, 2024-01-17) Mataba, Gordian; Ojija ·, Fredrick; Munishi, Linus
Lakes are among the main sources of protein and livelihood to huge communities of rural people, and some of them house endemic fish species. The livelihood of about 200,000 rural people depends on Lake Manyara resources which also houses a pop- ulation of the endemic and endangered fish, the Man- yara Tilapia (Oreochromis amphimelas). Despite this importance, fishery in the lake is nearly under open access and it is not known how this has affected fish stocks. The lake is also under strong influence from
Influence of land use on the abundance and spatial distribution of mosquito larvae of the Anopheles gambiae complex in a malaria expansion area in northern Tanzania
(Springer International Publishing, 2024-04) Mataba, Gordian; Munishi, Linus; Brendonck, Luc; Vanschoenwinkel, Bram
In many countries, successful control of larval mosquito populations for malaria control is still hindered by poor knowledge of preferred breeding habitats and natural factors limiting larval abundance. In Africa, preferred breeding habitats for malaria mosquitoes vary regionally and for many regions, they are still not well known. Moreover, variables that limit abundance of larvae of malaria mosquitoes are still ambiguous and impacts of surrounding land use practices are unclear. To study this, we sampled mosquito larvae from 164 small ground habitats (SGHs) in the lake Manyara basin (LMB) in northern Tanzania, a malaria expansion area with diverse land use types. We found that Anopheles gambiae s.l. was the only malaria mosquito breeding in SGHs in the region and its abundance was positively affected by turbidity and proximity to human dwellings. SGHs appear to be the major breeding sites for An. gambiae s.l. in the LMB despite the presence of larger temporary ponds which support negligible numbers of this species. In this region, we recommend that control of malaria via control of population of larval An. gambiae s.l. should prioritize SGHs to optimize use of limited resources and avoid damage to the environment by targeting unimportant habitats.
Interactive effects of dragonfly larvae andBacillusthuringiensisvar.israelensison mosquito ovipositionand survival
(John Wiley & Sons, Inc., 2023-09-05) Mataba, Gordian; Clark, Nicholas; Kweka, Eliningaya; Munishi, Linus; Brendonck, Luc; Vanschoenwinkel, Bram
The biological larvicide Bacillus thuringiensis var. israelensis (Bti) is used worldwide to control reproduction of mosquitoes in freshwater habitats. However, its impact on the ecosystem including nontarget species is often unclear. In addition, it is unknown how Bti larvicide may interact with local mosquito predators to shape oviposition site selection of mosquitoes. We used an outdoor mesocosm experiment to investigate the effects of realistic concentrations of the bio-larvicide Bti on Culex oviposition, larval density, survivorship, and on densities of nontarget species. We also manipulated the complexity of the community by manipulating the presence of dragonfly larvae as a predator. Culex oviposition was unaffected by Bti but the larvicide effectively reduced larval density and survivorship in all treatments. Bti did not affect nontarget insects but stimulated phytoplankton density at the expense of lower herbivore density. The presence of dragonfly larvae in mesocosms did not reduce Culex oviposition or larval sensitivity to Bti. We conclude that Bti may effectively reduce the density and survivorship of Culex quinquefasciatus mosquitoes in this part of East Africa, but possibly at the cost of higher phytoplankton densities. Bti-treated mesocosms were not more or less attractive for mosquitoes, suggesting that its application would not alter their oviposition behavior in the field.
Keep your natural enemies close – native predators can maintain low mosquito densities in temporary ponds in a malaria expansion area in Northern Tanzania
(Elsevier, 2021-11-10) Mataba, Gordian; Kafula, Yusuph; Mwaijengo, Grite; Snoeks, Joren; Munishi, Linus; Brendonck, Luc; Vanschoenwinkel, Bram
Mosquitoes and the diseases they transmit are a global public health threat that affects most human populations. Mosquito abundances are strongly linked to the number of suitable larval habitats available. However, it is still not well understood how different land uses impact larval habitat quality in different parts of the world. We investigated links between land use practices and abundance of mosquito larvae in temporary ponds located in different land uses in a malaria expansion zone in Tanzania. Temporary ponds are often cited as important sources of mosquitoes but are also of substantial conservation concern being home to a unique fauna and flora. Often, they also have high socio-economic importance. Overall, encountered mosquito larval abundances were very low, both for the collected Anopheles gambiae s.l. and Culex quinquefasciatus. Although temporary ponds are important mosquito larval habitats in other parts of Africa, currently they are unlikely to be an important factor affecting the prevalence of mosquito borne diseases in the Manyara study region. Larval abundances in temporary ponds were higher in agricultural areas where more eutrophic conditions were found and minimal in residential areas. Overall, even though temporary ponds are often modified as rice paddies in the rainy season, they were in a good ecological condition and hosted a diverse assemblage of aquatic predators that likely prevented larval mosquitoes from reaching high densities. Maintaining this good condition by preventing pesticide and nutrient input as much as possible, can be important to prevent pond degradation that is likely to make these habitats more suitable for mosquitoes in the future.
Large branchiopod occurrence and community structure in relation to land-use types in temporary ponds of northern Tanzania
(Springer Nature Switzerland AG., 2023-02-14) Kafula, Yusuph; Mataba, Gordian; Mwaijengo, Grite; Lemmens, Pieter; Munishi, Linus; Moyo, Francis; Dube, Trevor; Vanschoenwinkel, Bram; Brendonck, Luc
Large branchiopods are a key component of the fauna of temporary ponds and play an important role in the functioning of these vulnerable ecosystems. Owing to the establishment of new settlements and agricultural expansion, temporary ponds in Tanzania are disappearing at an alarming rate whilst little is known about their diversity and ecology. We contrasted temporary ponds from a protected area with those in communal lands to detect associations between land-use types and large branchiopod community structure. Six large branchiopod species were collected, five of which have been previously reported from Southern Africa, whilst one turned out to be new to science: Streptocephalus manyarensis n.sp. Kafula and Brendonck (2023). The clam shrimp Cyzicus sp., fairy shrimps Streptocephalus lamellifer Thiele (1900) and S. bourquinii Hamer and Appleton (1993) were the most abundant and widely occurring. Variation in large branchiopod community structure was explained by the presence of Nothobranchius killifish and orthophosphate concentration. The large branchiopod community structure was different in settlement and protected areas. Our study on the occurrence and structure of large branchiopod communities in relation to land-use types serves as a base for formulation of guidelines and management tools to regulate land-use practices adjacent to temporary pond ecosystems.
The role of anthropogenic container habitats as mosquito oviposition habitats in rural settlements in northern Tanzania
(BioOne Digital Library, 2022-04-05) Mataba, Gordian; Munishi, Linus; Brendonck, Luc; Vanschoenwinkel, Bram
Abstract In many areas, the main sources of mosquito vectors are not natural habitats but small artificial water bodies that are provided unintentionally by humans. Such container habitats have been linked to outbreaks of dengue fever and other arboviral diseases. However, in many parts of the world the possible risks associated with container habitats have not been assessed. Here, we focused on a human population expansion area in northern Tanzania with a high incidence of dengue and other cases of high fever. We explored the importance of anthropogenic container habitats for mosquito production in the Lake Manyara Basin. We also assessed how biotic and physicochemical habitat characteristics limit mosquito abundance in containers. Results showed that Aedes aegypti (Linnaeus), vector of dengue and other arboviruses, and Culex quinquefasciatus (Say), vector of filarial worms, were the dominant mosquitoes ovipositing in large numbers in different containers. Old tires were the dominant and most productive container habitat for mosquitoes in the region. However, there were strong differences among villages, illustrating that the mosquito burden associated with container habitats varies locally. We concluded that in this region, removal of artificial container habitats could be a simple strategy to reduce the mosquito-mediated disease burden within the local population.
Systematic literature review of bacterial larvicides Bacillus thuringiensis var israelensis and Bacillus (Lysinibacillus) sphaericus for malaria control in Africa
(Taylor and Fransis, 2025) Mataba, Gordian
A systematic review of the scientific literature was conducted with the objective offinding evidence on the contribution of microbial larvicides, Bacillus thuringiensis varisraelensis and Bacillus sphaericus, in clinical malaria burden in Africa. A systematic literature search was carried out using databases PubMed, Scopus, Web of Science, ProQuest, and BASE, and Google, and Google Scholar search engines. All results were screened for duplicates and assessed for eligibility. Relevant data were extracted, and a quality assessment was performed using the CONSORT 2010 checklist, funnel plot, and Egger’s regression test. Results show that 54 studies satisfied the eligibility criteria, and most were small-scale field trials. Most studies reported that Bti/Bs reduced the density of larvae of primary malaria vectors by 50%–100%. However, only 14 studies reported a subsequent reduction of malaria incidences, which was 31–62%. Furthermore, only one study evaluated the outcome of including Bti in a large-scale countrywide routine malaria control program, and it was in São Tomé and Príncipe. Overall, reviewed studies revealed a serious lack of Bti/Bs large-scale studies, and Bti/Bs inclusion in routine malaria control programs in most African countries. This impedes the formulation of evidence-based public health policies and frameworks for malaria elimination on the continent.