Exceedingly high proportions of Plasmodium-infected Anopheles funestus mosquitoes in two villages in the Kilombero valley, south-eastern Tanzania

Background: In south-eastern Tanzania where insecticide-treated nets have been widely used for more than 20 years, malaria transmission has greatly reduced but remains highly heterogenous over small distances. This study investigated the seasonal prevalence of Plasmodium sporozoite infections in the two main malaria vector species, Anopheles funestus and Anopheles arabiensis for 34 months, starting January 2018 to November 2020. Methods: Adult mosquitoes were collected using CDC-light traps and Prokopack aspirators inside local houses in Igumbiro and Sululu villages, where earlier surveys had found very high densities of An. funestus. Collected females were sorted by taxa, and the samples examined using ELISA assays for detecting Plasmodium falciparum circumsporozoite protein (Pf-CSP). Results: Of 7,859 An. funestus tested, 4.6% (n = 365) were positive for Pf sporozoites in the salivary glands. On the contrary, only 0.4% (n = 9) of the 2,382 An. arabiensis tested were positive. The sporozoite prevalence did not vary significantly between the villages (p = 0.36) or seasons (p = 0.59). Similarly, the proportions of parous females of either species were not significantly different between the two villages (p > 0.05) but was slightly higher in An. funestus (0.50) than in An. arabiensis (0.42). Analysis of the 2020 data determined that An. funestus contributed 98% of all malaria transmitted in households in these two villages. Conclusions: Despite the widespread use and overall impact of ITNs, there is still excessively high Plasmodium infection prevalence in the dominant malaria vector, An. funestus, causing intense year-round malaria transmission in the study villages. Further reduction in malaria burden thus requires effective targeting of An. funestus in these and other villages with similar epidemiological conditions.

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Anopheles funestus mosquitoes from rural south-eastern Tanzania may have stronger resistance to pyrethroids than the other malaria vector, Anopheles arabiensis

10.21203/rs.3.rs-19762/v2 ◽

2020 ◽

Author(s):

Polius Gerazi Pinda ◽

Claudia Eichenberger ◽

Halfan S Ngowo ◽

Dickson S Msaky ◽

Said Abbasi ◽

...

Keyword(s):

Malaria Transmission ◽

Anopheles Arabiensis ◽

Pyrethroid Resistance ◽

Anopheles Funestus ◽

Indoor Residual Spraying ◽

The Other ◽

Sub Saharan Africa ◽

Malaria Vectors ◽

Insecticide Treated Nets ◽

South Eastern

Abstract Background: Long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) have greatly reduced malaria transmission in sub-Saharan Africa, but are threatened by insecticide resistance. In south-eastern Tanzania, pyrethroid-resistant Anopheles funestus are now implicated in > 80% of malaria infections, even in villages where the species occurs at lower densities than the other vector species, Anopheles arabiensis. This study compared the intensities of resistance between the two malaria vectors, so as to improve options for control. Methods: The study used WHO assays with 1×, 5× and 10× insecticide doses to assess levels of resistance, followed by synergist bioassays to understand possible mechanisms of the observed resistance phenotypes. The tests involved adult mosquitoes collected from villages across two districts in south-eastern Tanzania and identified using morphological and molecular approaches.Findings: At baseline doses (1×), both species were resistant to the two pyrethroids (permethrin and deltamethrin) but susceptible to the organophosphate (pirimiphos-methyl). An. funestus, but not An. arabiensis was also resistant to the carbamate (bendiocarb) at baseline doses. Both species were generally resistant to DDT, except An.arabiensis from one village. An. funestus showed strong resistance to pyrethroids, surviving the 5× and 10× doses except in one village. Pre-exposure to the synergist, piperonyl butoxide (PBO), enhanced the potency of pyrethroid in both An. arabiensis and An. funestus achieving mortalities >98%, except for An. funestus from two villages for which permethrin-associated mortalities exceeded 90% but not 98%. Conclusions: In these communities where An. funestus dominates malaria transmission, this study may suggest that the species also have much stronger resistance to pyrethroids than its counterpart, An. arabiensis and can survive more classes of insecticides, including carbamates. The pyrethroid resistance in both species appears to be mostly metabolic and may be temporarily addressed using synergists, e.g. PBO. These findings may explain the continued persistence and dominance of An. funestus despite widespread use of pyrethroid-treated LLINs, and inform new choices of interventions to tackle malaria transmission in such settings. These may include PBO-based LLINs or improved IRS with compounds to which the vectors are susceptible. Additional field validation of these indications will be necessary using age-synchronized mosquitoes.

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The dominant malaria vector, Anopheles funestus from rural south-eastern Tanzania, is more strongly resistant to insecticides than Anopheles arabiensis

10.21203/rs.3.rs-19762/v1 ◽

2020 ◽

Cited By ~ 1

Author(s):

Polius Gerazi Pinda ◽

Claudia Eichenberger ◽

Halfan S Ngowo ◽

Dickson S Msaky ◽

Said Abbasi ◽

...

Keyword(s):

Malaria Transmission ◽

Pyrethroid Resistance ◽

Mosquito Species ◽

Anopheles Funestus ◽

Indoor Residual Spraying ◽

Sub Saharan Africa ◽

Malaria Vectors ◽

Insecticide Treated Nets ◽

South Eastern ◽

Sub Saharan

Abstract Background: Long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) have greatly reduced malaria transmission in sub-Saharan Africa, but are threatened by insecticide resistance in dominant malaria vectors. In south-eastern Tanzania, pyrethroid-resistant Anopheles funestus now transmit more than 80% of malaria infections even in villages where the species occurs at far lower densities than other vectors such as Anopheles arabiensis.Methods: To better understand the dominance of An. funestus in these settings and improve options for its control, this study compared intensities of resistance between females of this species and those of An. arabiensis , using WHO assays with 1×, 5× and 10× insecticide doses. Additional tests were done to assess the reversibility of such resistance using synergists. The mosquitoes were collected from villages across two districts in south-eastern Tanzania.Findings: Both species were resistant to the two pyrethroids (permethrin and deltamethrin) and the organochloride (DDT) but susceptible to the organophosphate (pirimiphos-methyl) at standard baseline doses (1×). However, An. funestus as opposed to An. arabiensis was also resistant to the carbamate (bendiocarb) at standard doses (1×). An. funestus showed strong resistance to pyrethroids, surviving the 5× doses and 10× doses except in one village. Pre-exposure to the synergist, piperonyl butoxide (PBO), reversed the pyrethroid-resistance in both An. arabiensis and An. funestus achieving mortalities >98%, except for An. funestus from two villages for which permethrin-associated mortalities exceeded 90% but not 98%.Conclusions : In these communities where An. funestus now dominates malaria transmission, the species also displays much stronger resistance to pyrethroids than its counterpart, An. arabiensis, and can readily survive more classes of insecticides, including carbamates. The resistance to pyrethroids in both mosquito species appears to be mostly metabolic and can be reversed significantly using synergists such as PBO. These findings may explain the continued persistence and dominance of An. funestus despite widespread use of pyrethroid-treated LLINs, and will also inform future choices of interventions to tackle malaria transmission in this area and other similar settings. Such interventions may include PBO-based LLINs or improved IRS with compounds such as organophosphates against which the vectors are still susceptible.

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Mapping Malaria Transmission Risk in Northern Morocco Using Entomological and Environmental Data

Malaria Research and Treatment ◽

10.4061/2011/391463 ◽

2011 ◽

Vol 2011 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

E. Adlaoui ◽

C. Faraj ◽

M. El Bouhmi ◽

A. El Aboudi ◽

S. Ouahabi ◽

...

Keyword(s):

Plasmodium Vivax ◽

Malaria Transmission ◽

Satellite Imagery ◽

Malaria Vector ◽

Environmental Changes ◽

Temporal Variations ◽

Environmental Data ◽

Transmission Risk ◽

Cultivation Period ◽

Very High

Malaria resurgence risk in Morocco depends, among other factors, on environmental changes as well as the introduction of parasite carriers. The aim of this paper is to analyze the receptivity of the Loukkos area, large wetlands in Northern Morocco, to quantify and to map malaria transmission risk in this region using biological and environmental data. This risk was assessed on entomological risk basis and was mapped using environmental markers derived from satellite imagery. Maps showing spatial and temporal variations of entomological risk for Plasmodium vivax and P. falciparum were produced. Results showed this risk to be highly seasonal and much higher in rice fields than in swamps. This risk is lower for Afrotropical P. falciparum strains because of the low infectivity of Anopheles labranchiae, principal malaria vector in Morocco. However, it is very high for P. vivax mainly during summer corresponding to the rice cultivation period. Although the entomological risk is high in Loukkos region, malaria resurgence risk remains very low, because of the low vulnerability of the area.

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The genetic basis of host choice and resting behavior in the major African malaria vector, Anopheles arabiensis

10.1101/044701 ◽

2016 ◽

Author(s):

Bradley J Main ◽

Yoosook Lee ◽

Heather M Ferguson ◽

Katharina S Kreppel ◽

Anicet Kihonda ◽

...

Keyword(s):

Malaria Vector ◽

Anopheles Arabiensis ◽

Genetic Basis ◽

Host Choice ◽

Genetic Component ◽

Insecticide Treated Nets ◽

Genome Wide ◽

Kilombero Valley ◽

Resting Behavior ◽

Standard Arrangement

AbstractMalaria transmission is dependent on the propensity of Anopheles mosquitoes to bitehumans (anthropophily) instead of other dead end hosts. Recent increases in the usage of Long Lasting Insecticide Treated Nets (LLINs) in Africa have been associated with reductions in highly anthropophilic vectors such as Anopheles gambiae s.s.,leaving less anthropophilic species such as Anopheles arabiensis as the most prominent remaining source of transmission in many settings. An.arabiensis is more of a generalist in terms of its host choice and resting behavior, which may be due to phenotypic plasticity and/or segregating allelic variation. To investigate the potential genetic basis of host choice and resting behavior in An. arabiensis we performed a genome-wide association study on host choice (human-or cattle-fed) and resting position (collected indoors or outdoors) in the Kilombero Valley, Tanzania. This represents the first genomic/molecular analysis of host choice and resting behavior in a malaria vector. We identified a total of 4,820,851 SNPs, which were used to conduct the first genome-wide estimates of 'SNP heritability' for host choice and resting behavior in this species. A genetic component was detected for host choice (human vs cow fed; permuted P = 0.002), but there was no evidence of a genetic component for resting behavior (indoors versus outside; permuted P = 0.465). A principal component analysis (PCA) segregated individuals based on genomic variation into three groups which are characterized by differences at the 2Rb and/or 3Ra paracentromeric chromosome inversions. There was a non-random distribution of cattle-fed mosquitoes between the PCA clusters, suggesting that alleles linked to the 2Rb and/or 3Ra inversions may influence host choice. Using a novel inversion genotyping assay, we detected a significant enrichment of the standard arrangement (non-inverted) of 3Ra among cattle-fed mosquitoes (N=129) versus all non-cattle-fed individuals (N=234; १2, p=0.007). Thus, tracking the frequency of the 3Ra in An. arabiensis populations is important, especially in relation to the emergence of behavioral avoidance(e.g. shifting toward cattle-feeding) in some populations. A better understanding of the genetic basis for host choice in An. arabiensis may also open avenues for novel vector control strategies based on introducing genes for zoophily into wild mosquito populations.Author summaryMalaria transmission is driven by the propensity for mosquito vectors to bite people, whilst its control depends on the tendency of mosquitoes to bite and rest in places where they will come into contact with insecticides. In many parts of Africa, Anopheles arabiensis is now the only remaining vec 63 tor in areas where coverage with Long Lasting Insecticide Treated Nets is high. We sought to assess the potential for An. arabiensis to adapt its behavior to avoid control measures by investigating the genetic basis for its host choice and resting behavior. Blood fed An. arabiensis were collected resting indoors and outdoors in the Kilombero Valley, Tanzania. We sequenced a total of 48 genomes representing 4 phenotypes (human or cow fed, resting in or outdoors) and tested for a genetic basis for each phenotype. Genomic analysis followed up by application of a novel molecular karyotyping assay revealed a relationship between An. arabiensis that fed on cattle and the standard arrangement of the 3Ra inversion. This indicates that the host choice behavior of An. arabiensis has has a substantial genetic component. Validation with controlled host preference assays comparing individuals with the standard and inverted arrangement of 3Ra is still needed.

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Using Bayesian state-space models to understand the population dynamics of the dominant malaria vector, Anopheles funestus in rural Tanzania

10.21203/rs.3.rs-1209027/v1 ◽

2022 ◽

Author(s):

Halfan Ngowo ◽

Fredros Oketch Okumu ◽

Emmanuel Elirehema Hape ◽

Issa H Mshani ◽

Heather M Ferguson ◽

...

Keyword(s):

Population Dynamics ◽

Density Dependence ◽

State Space ◽

Malaria Transmission ◽

Larval Development ◽

Malaria Vector ◽

Anopheles Funestus ◽

Model Fit ◽

Adult Survival ◽

Series Data

Abstract Background: It is often assumed that the population dynamics of the malaria vector Anopheles funestus, its role in malaria transmission and the way it responds to interventions are similar to the more elaborately characterized An. gambiae. However, An. funestus has several unique ecological features that could generate distinct transmission dynamics and responsiveness to interventions. The objectives of this work were to develop a model which will; 1) reconstruct the population dynamics, survival, and fecundity of wild An. funestus populations in southern Tanzania, 2) quantify impacts of density dependence on the dynamics, and 3) assess seasonal fluctuations in An. funestus demography. Through quantifying the population dynamics of An. funestus, this model will enable analysis of how their stability and response to interventions may different from that of An. gambiae s.l.Methods: A Bayesian State Space Model (SSM) based on mosquito life history was fit to time series data on the abundance of female An. funestus s.s. collected over 2 years in southern Tanzania. Prior values of fitness and demography were incorporated from empirical data on larval development, adult survival and fecundity from laboratory-reared first generation progeny of wild caught An. funestus. The model was structured to allow larval and adult fitness traits to vary seasonally in response to environmental covariates (i.e. temperature and rainfall), and for density dependency in larvae. We measured the effects of density dependence and seasonality through counterfactual examination of model fit with or without these covariates.Results: The model accurately reconstructed the seasonal population dynamics of An. funestus and generated biologically-plausible values of their survival larval, development and fecundity in the wild. This model suggests that An-funestus survival and fecundity annual pattern was highly variable across the year, but did not show consistent seasonal trends either rainfall or temperature. While the model fit was somewhat improved by inclusion of density dependence, this was a relatively minor effect and suggests that this process is not as important for An. funestus as it is for An. gambiae populations.Conclusion: The model's ability to accurately reconstruct the dynamics and demography of An. funestus could potentially be useful in simulating the response of these populations to vector control techniques deployed separately or in combination. The observed and simulated dynamics also suggests that An. funestus could be playing a role in year-round malaria transmission, with any apparent seasonality attributed to other vector species.

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Comparative assessment of insecticide resistance phenotypes in two major malaria vectors, Anopheles funestus and Anopheles arabiensis in south-eastern Tanzania

Malaria Journal ◽

10.1186/s12936-020-03483-3 ◽

2020 ◽

Vol 19 (1) ◽

Author(s):

Polius G. Pinda ◽

Claudia Eichenberger ◽

Halfan S. Ngowo ◽

Dickson S. Msaky ◽

Said Abbasi ◽

...

Keyword(s):

Insecticide Resistance ◽

Malaria Transmission ◽

Anopheles Arabiensis ◽

Pyrethroid Resistance ◽

Anopheles Funestus ◽

Indoor Residual Spraying ◽

Sub Saharan Africa ◽

World Health ◽

Malaria Vectors ◽

South Eastern

Abstract Background Long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) have greatly reduced malaria transmission in sub-Saharan Africa, but are threatened by insecticide resistance. In south-eastern Tanzania, pyrethroid-resistant Anopheles funestus are now implicated in > 80% of malaria infections, even in villages where the species occurs at lower densities than the other vector, Anopheles arabiensis. This study compared the insecticide resistance phenotypes between the two malaria vectors in an area where pyrethroid-LLINs are widely used. Methods The study used the World Health Organization (WHO) assays with 1×, 5× and 10× insecticide doses to assess levels of resistance, followed by synergist bioassays to understand possible mechanisms of the observed resistance phenotypes. The tests involved adult mosquitoes collected from three villages across two districts in south-eastern Tanzania and included four insecticide classes. Findings At baseline doses (1×), both species were resistant to the two candidate pyrethroids (permethrin and deltamethrin), but susceptible to the organophosphate (pirimiphos-methyl). Anopheles funestus, but not An. arabiensis was also resistant to the carbamate (bendiocarb). Both species were resistant to DDT in all villages except in one village where An. arabiensis was susceptible. Anopheles funestus showed strong resistance to pyrethroids, surviving the 5× and 10× doses, while An. arabiensis reverted to susceptibility at the 5× dose. Pre-exposure to the synergist, piperonyl butoxide (PBO), enhanced the potency of the pyrethroids against both species and resulted in full susceptibility of An. arabiensis (> 98% mortality). However, for An. funestus from two villages, permethrin-associated mortalities after pre-exposure to PBO only exceeded 90% but not 98%. Conclusions In south-eastern Tanzania, where An. funestus dominates malaria transmission, the species also has much stronger resistance to pyrethroids than its counterpart, An. arabiensis, and can survive more classes of insecticides. The pyrethroid resistance in both species appears to be mostly metabolic and may be partially addressed using synergists, e.g. PBO. These findings may explain the continued persistence and dominance of An. funestus despite widespread use of pyrethroid-treated LLINs, and inform new intervention choices for such settings. In short and medium-term, these may include PBO-based LLINs or improved IRS with compounds to which the vectors are still susceptible.

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Evaluating the Evidence from Molecular Structure and Population Studies for Cross-Resistance to the Pyrethroids Used in Malaria Vector Control

10.21203/rs.3.rs-104446/v1 ◽

2020 ◽

Author(s):

Catherine L. Moyes ◽

Rosemary S. Lees ◽

Cristina Yunta ◽

Kyle J. Walker ◽

Kay Hemmings ◽

...

Keyword(s):

Binding Affinity ◽

Malaria Vector ◽

Pyrethroid Resistance ◽

Anopheles Funestus ◽

Malaria Vectors ◽

Cross Resistance ◽

Malaria Vector Control ◽

Insecticide Treated Nets ◽

The Common ◽

The Impact

Abstract The primary malaria control intervention in high burden countries is the deployment of long-lasting insecticide-treated nets (LLINs) treated with pyrethroids, alone or in combination with a second active ingredient or synergist. It is essential to understand whether the impact of pyrethroid resistance can be mitigated by switching between different pyrethroids or whether cross-resistance precludes this. Structural diversity within the pyrethroids could mean some compounds are better able to counteract the resistance mechanisms that have evolved in malaria vectors. Here we consider variation in vulnerability to the P450 enzymes that confer metabolic pyrethroid resistance in Anopheles gambiae s.l. and Anopheles funestus. We assess the relationships among pyrethroids in terms of their binding affinity to key P450s and the percent depletion by these P450s, in order to identify which pyrethroids diverge from the others. We then investigate whether these same pyrethroids also diverge from the others in terms of resistance in vector populations. We found that etofenprox, which lacks the common structural moiety of other pyrethroids, potentially diverges from the commonly deployed pyrethroids in terms of P450 binding affinity and resistance in malaria vector populations, but not depletion by the P450s tested. These results are supplemented by an analysis of resistance to the same pyrethroids in Aedes aegypti populations, which also found etofenprox diverges from the other pyrethroids in terms of resistance in wild populations. In addition, we found that bifenthrin, which also lacks the common structural moiety of most pyrethroids, diverges from the commonly deployed pyrethroids in terms of P450 binding affinity and depletion by P450s. However, resistance to bifenthrin in vector populations is largely untested. The prevalence of resistance to the pyrethroids α-cypermethrin, cyfluthrin, deltamethrin, λ-cyhalothrin, and permethrin was correlated across malaria vector populations and switching between these compounds as a tool to mitigate against pyrethroid resistance is not advised without strong evidence supporting a true difference in resistance.

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Comparative assessment of insecticide resistance phenotypes in two major malaria vectors, Anopheles funestus and Anopheles arabiensis in south-eastern Tanzania

10.21203/rs.3.rs-19762/v3 ◽

2020 ◽

Author(s):

Polius Gerazi Pinda ◽

Claudia Eichenberger ◽

Halfan S Ngowo ◽

Dickson S Msaky ◽

Said Abbasi ◽

...

Keyword(s):

Insecticide Resistance ◽

Malaria Transmission ◽

Anopheles Arabiensis ◽

Pyrethroid Resistance ◽

Anopheles Funestus ◽

Indoor Residual Spraying ◽

Sub Saharan Africa ◽

World Health ◽

Malaria Vectors ◽

South Eastern

Abstract BackgroundLong-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) have greatly reduced malaria transmission in sub-Saharan Africa, but are threatened by insecticide resistance. In south-eastern Tanzania, pyrethroid-resistant Anopheles funestus are now implicated in > 80% of malaria infections, even in villages where the species occurs at lower densities than the other vector, Anopheles arabiensis. This study compared the insecticide resistance phenotypes between the two malaria vectors in an area where pyrethroid-LLINs are widely used.MethodsThe study used the World Health Organization (WHO) assays with 1×, 5× and 10× insecticide doses to assess levels of resistance, followed by synergist bioassays to understand possible mechanisms of the observed resistance phenotypes. The tests involved adult mosquitoes collected from three villages across two districts in south-eastern Tanzania and included four insecticide classes.FindingsAt baseline doses (1×), both species were resistant to the two candidate pyrethroids (permethrin and deltamethrin), but susceptible to the organophosphate (pirimiphos-methyl). Anopheles funestus, but not An. arabiensis was also resistant to the carbamate (bendiocarb). Both species were resistant to DDT in all villages except in one village where An. arabiensis was susceptible. Anopheles funestus showed strong resistance to pyrethroids, surviving the 5× and 10× doses, while An. arabiensis reverted to susceptibility at the 5× dose. Pre-exposure to the synergist, piperonyl butoxide (PBO), enhanced the potency of the pyrethroids against both species and resulted in full susceptibility of An. arabiensis (>98% mortality). However, for An. funestus from two villages, permethrin-associated mortalities after pre-exposure to PBO only exceeded 90% but not 98%.ConclusionsIn south-eastern Tanzania, where An. funestus dominates malaria transmission, the species also has much stronger resistance to pyrethroids than its counterpart, An. arabiensis, and can survive more classes of insecticides. The pyrethroid resistance in both species appears to be mostly metabolic and may be partially addressed using synergists, e.g. PBO. These findings may explain the continued persistence and dominance of An. funestus despite widespread use of pyrethroid-treated LLINs, and inform new intervention choices for such settings. In short and medium-term, these may include PBO-based LLINs or improved IRS with compounds to which the vectors are still susceptible.

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Aquatic habitats of the malaria vector Anopheles funestus in rural south-eastern Tanzania

Malaria Journal ◽

10.1186/s12936-020-03295-5 ◽

2020 ◽

Vol 19 (1) ◽

Cited By ~ 1

Author(s):

Ismail H. Nambunga ◽

Halfan S. Ngowo ◽

Salum A. Mapua ◽

Emmanuel E. Hape ◽

Betwel J. Msugupakulya ◽

...

Keyword(s):

Malaria Vector ◽

Anopheles Funestus ◽

Aquatic Habitats ◽

Rural South ◽

South Eastern

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Aquatic habitats of the malaria vector, Anopheles funestus in rural south-eastern Tanzania

10.21203/rs.3.rs-20420/v2 ◽

2020 ◽

Author(s):

Ismail Hassani Nambunga ◽

Halfan S. Ngowo ◽

Salum A. Mapua ◽

Emmanuel E. Hape ◽

Betwel J. Msugupakulya ◽

...

Keyword(s):

Malaria Vector ◽

Control Strategies ◽

Mosquito Species ◽

Anopheles Funestus ◽

Survival Strategies ◽

Aquatic Habitats ◽

Rural South ◽

South Eastern ◽

Ecological Requirements ◽

Slow Moving

Abstract Background: In rural south-eastern Tanzania, Anopheles funestus are a major malaria vector, and have been implicated in nearly 90% of infective bites. However, little is known about the natural ecological requirements and survival strategies of this mosquito species.Methods: Potential mosquito aquatic habitats were systematically searched along 1000 m transects radiating from the centres of six villages in south-eastern Tanzania. All water bodies were geo-referenced, characterized and examined for presence of Anopheles larvae using standard 350mls dippers or 10L buckets. Larvae were collected for rearing, and the emergent adults identified to generic or species level, to confirm habitats containing An. funestus. Results: One hundred and eleven (111) habitats were identified and assessed from the first five villages (all <300m altitude). Of these, 36 (32.4%) had An. funestus larvae co-occurring with other mosquito species. Another 47 (42.3%) had other Anopheles species and/or culicines but not An. funestus, and 28 (25.2%) had no mosquitoes. There were three main habitat types occupied by An. funestus, namely: a) small spring-fed pools with well-defined perimeters (36.1%), b) medium-sized natural ponds retaining water most of the year (16.7%), and c) slow-moving waters along river tributaries (47.2%). The habitats generally had clear waters with emergent surface vegetation, depths > 0.5m and distances < 100m from human dwellings. They were permanent or semi-permanent, retaining water most of the year. Water temperatures ranged from 25.2 to 28.8°C, pH from 6.5 to 6.7, turbidity from 26.6 to 54.8 NTU and total dissolved solids from 60.5 to 80.3 mg/L. In the sixth village (altitude >400m), very high densities of An. funestus were found along rivers with slow-moving clear waters and emergent vegetation.Conclusion: This study has documented the diversity and key characteristics of aquatic habitats of An. funestus in south-eastern Tanzania, and will form an important basis for further ecological studies towards improved control strategies. Given the observed characteristics, An. funestus habitats in the area can indeed be described as fixed, few and findable. Future studies should therefore investigate potential of targeting these habitats with larviciding or larval source management to complement malaria control efforts in areas dominated by this vector.

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