Since the turn of the century, long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) have played a major role in malaria control. However, the effectiveness of these tools is declining due to the development of insecticide resistance and other factors, creating an urgent need for complementary strategies. Larval source management (LSM), through the application of biological larvicides or the autodissemination of larvicides by ovipositing female mosquitoes, offers alternative avenues to target malaria vectors. Predicting the effectiveness of such approaches requires a detailed understanding of oviposition site selection behaviour in female Anopheles gambiae sensu lato. This study investigated the oviposition strategy of female Anopheles arabiensis in relation to aquatic habitat size under semi-field conditions in south-central Tanzania. An array of twelve alternating small (30 cm diameter, 20 L capacity) and large (60 cm diameter, 40 L capacity) artificial larval habitats was established in two compartments of a semi-field system. In quadruplicated experiments, forty wild gravid An. arabiensis females were released into each compartment and allowed to oviposit in their preferred habitats. The resulting third-instar larvae were collected, counted and preserved in ethanol. Larvae from one replicate were subjected to DNA extraction and microsatellite genotyping. Sibship analysis using Bayesian-likelihood methods (COLONY software) was conducted to reconstruct individual female oviposition behaviour. Rather than distributing eggs in proportion to habitat size, An. arabiensis females significantly preferred smaller habitats. Sibship analysis showed that 49.2

Background: Anopheles funestus, a major vector of malaria in Africa, has proven difficult to colonize in laboratory settings, impeding research on its biology and control. After several attempts, our team recently succeeded in colonizing a strain of An. funestus from Tanzania (FUTAZ). The objective of this study was to analyse the key fitness and genotypic characteristics of these mosquitoes during multiple filial generations of laboratory adaptation and compare them to wild An. funestus from Tanzania and a pre-existing colony of An. funestus from Mozambique (FUMOZ). Methods: Measures of mating success (percentage of female mosquitoes inseminated), body size (wing length), fecundity (number of eggs laid per female), and insecticide susceptibility (percentage of 24-hour mortality after exposure to insecticides) were compared between the newly established colonies of Tanzanian An. funestus (FUTAZ colonies), the long-established FUMOZ colonies, and a colony of Anopheles arabiensis maintained in the same laboratory. The maternal lineages of the An. funestus mosquitoes were investigated through a hydrolysis probe analysis of their mitochondrial DNA to identify distinct clades, I and II. Additionally, other intragenomic variations were examined through a PCR analysis of restriction fragment length polymorphisms (RFLP) on the third domain of 28S ribosomal DNA. These molecular markers were used to compare the FUTAZ colonies, FUMOZ colonies in Tanzania and South Africa, and the wild-collected An. funestus from Tanzania. Result: The mating success and body size of FUTAZ females declined significantly from filial generations F1 to F6 relative to the founder population (F0), but then increased from F7 onwards eventually matching FUMOZ by F9. Fecundity was similar across all colonies tested. However, it took significantly longer for 50% of the females in the FUTAZ and FUMOZ colonies (over 10 days) to mate compared to females in the An. arabiensis colony (approximately 5 days). Insecticide resistance appeared to be lost during colonization, but this varied with insecticide classes. Majority of mosquitoes in the FUTAZ colony, as well as the wild-caught Tanzanian An. funestus belonged to Clade I (80.4-89.4%) and RFLP type "Y" (90.5-91.4%), while the FUMOZ colonies were mostly Clade II (65.5-88.5%) and RFLP type "MW" (90.5-91.5%). Conclusion: This study suggests that the mating success and body size of An. funestus decreases significantly during the early stages of colonization, then increase as the mosquitoes adapt to laboratory conditions. It is therefore crucial to have a large enough founder population to persist through these early generations in order to achieve stable colonization of An. funestus. The Clade and RFLP genotyping demonstrated the genetic similarities between the FUTAZ mosquitoes and wild-caught Tanzanian An. funestus, but also showed that the new colony can be distinguished from the FUMOZ colony. ### Competing Interest Statement The authors have declared no competing interest.

Despite Anopheles funestus s.s. being a highly competent and widespread malaria vector in Africa, its population structure remains largely understudied in many countries, including Tanzania. Herein, we examine the genetic diversity, geographic isolation, and gene flow of An. funestus populations across ten administrative regions in mainland Tanzania. We employed 12 previously used microsatellite DNA markers to describe genetic diversity, isolation by distance, and gene flow patterns among ten An. funestus s.s. populations (n = 654) and one An. parensis population (n = 28), used as an outgroup, sampled across ten regions in mainland Tanzania. Overall, allelic richness (Na) and genetic diversity (HS) did not differ significantly among populations. Although some loci and populations showed significant departures from Hardy–Weinberg equilibrium, the patterns were not indicative of substructuring within locations. Pairwise genetic divergence (FST) values indicated clear separation between An. parensis and An. funestus s.s., with values exceeding 0.2, consistent with species-level differentiation. Among An. funestus s.s. populations, the highest divergence was observed between southeastern coastal populations (Mtwara, Ruvuma, Lindi) and inland populations, with FST values up to 0.288. There was no evidence of isolation by distance. Instead, patterns of genetic divergence suggested connectivity across the Rift Valley and heterogeneity among southeastern populations. Neighbor-joining analysis and Bayesian genotype clustering identified three distinct population groups: (i) An. parensis (Dodoma), (ii) a genetically distinct An. funestus s.s. population from Mtwara, and (iii) a more homogeneous cluster comprising the remaining An. funestus s.s. populations. Notably, the Mtwara population appeared highly differentiated, with divergence approaching that between An. funestus s.s. and An. parensis, supporting its distinctiveness but not undermining the role of An. parensis as an outgroup. Except for the Mtwara population, whose status will need to be clarified through whole-genome sequencing, moderate genetic divergence was found among An. funestus s.s. populations across Tanzania, despite geographical separation and the Rift Valley. The observed genetic structure suggests that anthropogenic gene flow may play a key role in shaping population divergence. Future studies should aim to delineate the effects of local adaptation from recent gene flow to further explore these dynamics

Insecticide-based strategies for mosquito control are increasingly constrained by insecticide resistance, sparking interest in eco-friendly alternatives, one of which is the use of aquatic predators to reduce mosquito densities. Evidence from laboratory, semi-field, and localized field studies indicates that aquatic predators can significantly reduce mosquito larval and adult densities. However, direct evidence linking these ecological effects to sustained reductions in mosquito-borne disease transmission remains limited. This review synthesizes current studies on the use of aquatic predators for mosquito control and examines their potential as a complementary biological strategy within integrated vector management programs. While aquatic predators show promise for suppressing mosquito populations through both consumptive and non-consumptive effects, further research is needed to evaluate their epidemiological impact, operational feasibility, cost-effectiveness, scalability, and long-term sustainability. Addressing these knowledge gaps will be essential for determining how predator-based approaches can be effectively integrated into existing vector control strategies.

Gene-drive mosquitoes could transform malaria control in Africa, but their rapid, autonomous spread requires rigorous post-release monitoring. Most malaria-endemic countries already conduct some entomological surveillance, although it is often limited, fragmented, and externally funded. Molecular diagnostics are also expanding but remain mostly research focused and ad hoc. These imperfect systems offer workable foundations for strategic upgrades to support essential gene-drive monitoring. Priority investments should strengthen field-entomology, high-throughput genotyping for drive alleles and resistance, technical expertise, and integrated data for decision-making. Fortunately, first-generation gene drives already align with common phenotyping and genotyping workflows, avoiding major infrastructure overhauls, and permit simpler evaluation metrics than conventional interventions. This feature review examines key technical and operational considerations for monitoring gene drives and recommends how countries can adapt their vector surveillance systems to effectively monitor gene-drive mosquito releases.

BackgroundMalaria transmission is highly sensitive to climatic variability, as changes in temperatures and rainfall, directly influence mosquito breeding, survival, and parasite development. Extreme climatic events, such as flooding, further exacerbate malaria risk by disrupting access to preventive, diagnostic and treatment services. However, there is limited evidence on how communities in malaria-endemic settings perceive and respond to the health impacts of climate variability and change. This study explored community knowledge, perceptions, and practices related to the relationship between climate variability and malaria transmission in south-eastern Tanzania.MethodsAn explanatory mixed-methods cross-sectional study was conducted in malaria-endemic villages in south-eastern Tanzania. Quantitative data were collected through structured questionnaires administered to 384 community members, while qualitative data were obtained through 11 key informant interviews and 12 focus group discussions involving 72 participants. Survey data were analysed descriptively, and qualitative data were analysed thematically.ResultsAmong survey respondents, 86% reported experiencing climate-related changes, including altered cropping seasons, increased flooding, and a perceived rise in vector-borne diseases. Approximately two-thirds (67.5%) recognized a link between climate change and malaria transmission. Perceived vulnerability was high, with 59.5% reporting increased risk of vector-borne diseases and 70% indicating higher malaria occurrence during the rainy season compared to the dry season. Access to timely climate and health information was limited, as only 26.6% regularly received updates, despite 96.6% expressing a desire for such information. Findings from focus group discussions and key informant interviews corroborated these perceptions and highlighted the need for targeted community awareness and education on climate-related malaria risks.ConclusionsCommunity members demonstrated awareness of climate change and its perceived impacts on malaria and livelihoods. These findings highlight the importance of integrating community perspectives and local knowledge into climate-adaptation and malaria-control strategies to enhance locally relevant and community-centered resilience.

Evidence-based decision making on malaria vector control strategies increasingly rely on triangulation of data which requires informatics systems that can integrate data from complex, multi-stage studies involving mosquitoes. This manuscript describes a performance evaluation of an extended version of the generic schema underpinning the VBDs360 platform, specifically improved to accommodate multiple distinct entomological assays spanning the field, insectary, and laboratory. The utility of this extension, with respect to high-fidelity data linkage and robust sample traceability across complex entomological workflows, was evaluated through a case study conducted in southern Tanzania. Wild female mosquitoes were collected from 40 locations across more than 4,000 square km and then reared through multiple generations in an insectary before derived iso-female lineages were tested for phenotypic susceptibility to a pyrethroid insecticide. Such multi-generational lineages (F0 to Fn; where n is greater than or equal to 2) were propagated to prevent non-heritable maternal effects on phenotype and produce enough progeny for standard WHO susceptibility assays. All samples were subsequently archived in a molecular laboratory, where all F0 specimens were tested for sibling species identity. A paper-based implementation of the extended schema enabled successful integration of 77,017 lines of data distributed across 6 different tables that spanned 3 distinct field, insectary, and laboratory workflows, implemented by three different teams working in different locations. At each step, fully independent and redundant primary and secondary keys enabled high fidelity error correction and sample tracing. Consistently perfect linkage between assay design and sample sorting data was achieved for F0 wild-caught adults, with 100% of 66,108 record successfully linked between field capture and morphological categorization. This complete traceability extended to the propagation of derived Fn lineages, with all 100 and 243 records from 9 adult-derived and 13 larval-derived lineages, respectively, correctly linked. Insecticide susceptibility phenotype further confirmed 100% linkage for 5,654 records between exposure history and recorded mortality outcome data in the insectary. Although such cross-cleaned linkages to sample analysis and storage data recorded by the laboratory team were not entirely perfect and could be improved, they were nevertheless of very high fidelity (97.3% (1967/2,022) for F0 samples and 99.3% (437/440) for Fn samples). Overall, this pilot application of the extended generic schema ensured robust data provenance and minimized transcription errors in this complex study distributed across multiple teams and locations. These findings demonstrate how this generic informatics framework may be scaled and adapted to support data integrity across diverse, large-scale, multi-team entomological research workflows.

Anopheles funestus, a major vector of malaria in Africa, has proven difficult to colonize in laboratory settings, impeding research on its biology and control. After several attempts, our team recently succeeded in colonizing a strain of An. funestus from Tanzania (FUTAZ). The objective of this study was to analyze the key fitness and genotypic characteristics of these mosquitoes during multiple filial generations of laboratory adaptation and compare them to wild An. funestus from Tanzania and a pre-existing colony of An. funestus from Mozambique (FUMOZ). Measures of mating success, body size, fecundity, and insecticide resistance were compared between the newly established FUTAZ colonies, the long-established FUMOZ colonies, and a colony of Anopheles arabiensis maintained in the same laboratory. The maternal lineages of the An. funestus mosquitoes were investigated through a hydrolysis probe analysis of their mitochondrial DNA to identify distinct clades. Other intragenomic variations were examined by D3-RFLP genotyping of 28S ribosomal DNA. These molecular markers were used to compare the FUTAZ colonies, FUMOZ colonies in Tanzania (TZ) and South African (SA) laboratories, and the wild-collected Tanzanian An. funestus. The mating success and body size of FUTAZ females declined significantly from filial generations F1 to F6 relative to the founder population (F0) then increased from F7 onwards, eventually matching FUMOZ by F9. Fecundity was similar across all colonies tested. However, it took significantly longer for 50

Larviciding forms an integral part of larval source management, a supplementary intervention for malaria vector control. However, if chemical larvicides are not thoroughly evaluated, non-target organisms in aquatic habitats may be harmed. Among these are aquatic predators, which play an important role in regulating mosquito populations. This study evaluated the effects of pyriproxyfen, an insect growth regulator, on nymph survival, adult emergence, and predatory ability of field-collected dragonfly, damselfly, and backswimmer nymphs under semi-field settings. Nymphs were exposed to 300 ppb pyriproxyfen for 21 days to assess survival, while emergence inhibition in dragonflies and damselflies was measured at 50 and 300 ppb with daily mosquito‐larvae provisioning until emergence or death. Predation bioassays at 150 and 300 ppb across larval densities (3, 6, 9 larvae/200 mL) were conducted over 6-hour (every 40 min) and 9-day (daily) intervals, with larvae replenished after each count. The findings indicated that a 300 ppb did not compromise the survival of predator nymphs (p > 0.05). In addition, 50 ppb and 300 ppb significantly inhibited damselfly emergence (p < 0.05), without affecting dragonflies (p > 0.05). With exception of damselflies, pyriproxyfen enhanced the predatory abilities of backswimmers and dragonflies. These findings demonstrate that pyriproxyfen exhibits a species-specific safety profile rather than uniform safety across aquatic predators. While having a higher safety margin in aquatic ecosystems harboring dragonflies and backswimmers, the observed emergence inhibition in sensitive species such as damselflies underscores the need for cautious, context-dependent application. Based on these findings, autodissemination of pyriproxyfen could be effectively integrated with existing interventions, providing a dual impact on immature mosquitoes through both the direct effects of chemicals and the enhanced predatory activity.

BACKGROUND:The feeding behaviours of the malaria vector Anopheles arabiensis, and its competitive relationships with other sibling species within the Anopheles gambiae complex, remain largely unexplored within well conserved natural ecosystems, where its known preferred hosts are scarce or absent. METHODS:Potential aquatic habitats were surveyed for An. gambiae complex larvae across a gradient of natural ecosystem integrity in southern Tanzania, encompassing fully domesticated human settlements, a partially encroached Wildlife Management Area (WMA), and well conserved natural ecosystems within Nyerere National Park (NNP). Direct observations, tracks, spoor and other signs of human, livestock or wild animal activity around these water bodies were recorded as indirect indicators of potential blood source availability. FINDINGS:While only An. arabiensis was found in fully domesticated ecosystems, its non-vector sibling species An. quadriannulatus occurred in conserved areas and dominated the most intact natural ecosystems. Proportions of larvae identified as An. arabiensis were positively associated with human and/or cattle activity and negatively associated with distance inside NNP and away from human settlements. Proportions of An. quadriannulatus were positively associated with activities of impala, warthog and possibly bushpig, implicating them as likely preferred blood hosts. While abundant impala and lack of humans or cattle in intact acacia savannah within NNP apparently allowed it to dominate An. arabiensis, presence of warthog seemed to provide it with a foothold in miombo woodlands of the WMA, despite encroachment there by people and livestock. While this antelope and suid are essentially unrelated, both are non-migratory residents of small home ranges with perennial surface water, representing potential hosts for An. quadriannulatus that are widespread across extensive natural ecosystems all year round. Despite dominance of An. quadriannulatus in well-conserved areas, An. arabiensis was even found in absolutely intact natural environments > 40km inside NNP, suggesting it can survive on blood from one or more unidentified wild species. Such self-sustaining refuge populations of An. arabiensis inside conservation areas, supported by wild blood hosts that are fundamentally beyond the reach of insecticidal interventions targeted at humans or livestock, may confound efforts to eliminate this key malaria vector. However, they might also enable insecticide resistance management strategies that could restore the effectiveness of pyrethroids in particular. This new approach to indirectly identifying commonly utilized blood sources may also be applicable to an unprecedented diversity of zoophagic mosquitoes, enabling incrimination of possible bridge vector species capable of mediating pathogen spillover from wildlife reservoirs into livestock and/or human populations.

Abstract Background Evidence of natural infection with Wolbachia and its negative correlation with Plasmodium falciparum among wild malaria vectors has opened new avenues for utilization of Wolbachia in malaria vector control. However, the interaction between Wolbachia and Plasmodium parasites in mosquitoes tends to be species-specific and may show ecological variations. Among the primary malaria vectors in Tanzania, natural Wolbachia infection has only been observed in Anopheles arabiensis, while there is still limited information on Wolbachia natural infection in Anopheles funestus sensu lato, and its interaction with P. falciparum in the mosquito species. Therefore, this study investigated the prevalence of natural infection and co-infection of Wolbachia and P. falciparum in the An. funestus s.l. in southeastern Tanzania, and characterized the Wolbachia strains detected. Methods The study was conducted in five villages in southeastern Tanzania between March and June 2024. Mosquitoes were collected from 52 households using Centers for Disease Control and Prevention (CDC) light traps and Prokopack aspirators, followed by morphological identification. Detection of An. funestus sibling species and Wolbachia was performed using conventional polymerase chain reaction (PCR) and nested PCR (Wolbachia only). Sanger sequencing was performed as a confirmatory test followed by phylogenetic analysis of the detected Wolbachia strains. P. falciparum sporozoites were detected using enzyme-linked immunosorbent assay (ELISA). Results Wolbachia was detected in almost half of all wild An. funestus s.l. tested using the primary PCR (prevalence = 46.5%, N = 400); and more than half when nested PCR approach was used (prevalence = 70.8%, N = 400). Only three mosquitoes carried P. falciparum sporozoites (prevalence = 0.8%, N = 400) and only one showed co-infection with Wolbachia (prevalence = 0.3%, n = 400). Sequencing and phylogenetic analysis involving both the 16S rDNA, coxA, and wsp Wolbachia genes showed that the detected strains clustered with Wolbachia supergroup B, specific for Dipterans. Conclusions Unlike findings from the previous study, this study demonstrates that An. funestus s.l. in southeastern Tanzania are infected with Wolbachia, at a surprisingly high prevalence. This study also provides the first report on Wolbachia–P. falciparum co-infection status in An. funestus s.l. in Tanzania. Further studies with larger sample sizes are needed to confirm the association between native Wolbachia and P. falciparum in wild An. funestus s.l. in southeastern Tanzania. Graphical Abstract

Abstract Larval source management (LSM) has a long history of advocacy and successes but is rarely adopted where funds are limited. The World Health Organization (WHO) guidelines on malaria prevention recommend the use of LSM as a supplementary intervention to the core vector control methods (insecticide-treated nets and indoor residual spraying), arguing that its feasibility in many settings can be limited by larval habitats being numerous, transient, and difficult to find or treat. Another key argument is that there is insufficient high-quality evidence for its effectiveness to support wide-scale implementation. However, the stagnation of progress towards malaria elimination demands that we consider additional options to the current emphasis on insecticidal commodities targeting adult mosquitoes inside homes. This letter is the result of a global, crossdisciplinary collaboration comprising: (a) detailed online expert discussions, (b) a narrative review of countries that have eliminated local malaria transmission, and (c) a mathematical modeling exercise using two different approaches. Together, these efforts culminated in seven key recommendations for elevating larval source management as a strategy for controlling malaria and other mosquito-borne diseases in Africa (Box 1). LSM encompasses the use of larvicide (a commodity) as well as various environmental sanitation measures. Together, these efforts lead to the long-term reduction of mosquito populations, which benefits the entire community by controlling both disease vector and nuisance mosquitoes. In this paper, we argue that the heavy reliance on large-scale cluster-randomized controlled trials (CRTs) to generate evidence on epidemiological endpoints restricts the recommendation of approaches to only those interventions that can be measured by functional units and deliver relatively uniform impact and, therefore, are more likely to receive financial support for conducting these trials. The explicit impacts of LSM may be better captured by using alternative evaluation approaches, especially high-quality operational data and a recognition of locally distinct outcomes and tailored strategies. LSM contributions are also evidenced by the widespread use of LSM strategies in nearly all countries that have successfully achieved malaria elimination. Two modelling approaches demonstrate that a multifaceted strategy, which incorporates LSM as a central intervention alongside other vector control methods, can effectively mitigate key biological threats such as insecticide resistance and outdoor biting, leading to substantial reductions in malaria cases in representative African settings. This argument is extended to show that the available evidence is sufficient to establish the link between LSM approaches and reduced disease transmission of mosquito-borne illnesses. What is needed now is a significant boost in the financial resources and public health administration structures necessary to train, employ and deploy local-level workforces tasked with suppressing mosquito populations in scientifically driven and ecologically sensitive ways. In conclusion, having WHO guidelines that recognize LSM as a key intervention to be delivered in multiple contextualized forms would open the door to increased flexibility for funding and aid countries in implementing the strategies that they deem appropriate. Financially supporting the scale-up of LSM with high-quality operations monitoring for vector control in combination with other core tools can facilitate better health. The global health community should reconsider how evidence and funding are used to support LSM initiatives. Graphical Abstract

Anopheles funestus s.s. is a major human malaria vector across Africa. To study its evolution, especially under vector control pressure, we sequenced 656 modern specimens (collected 2014 to 2018) and 45 historic specimens (collected 1927 to 1967) from 16 African countries. Despite high genetic diversity, the species shows stable but considerable continental population structure. Although one population showed little differentiation over a century and 4000 kilometers, nearby, we found two genetically distinct ecotypes. Vector control has resulted in strong signals of selection, with some resistance alleles shared across populations through gene flow and others arising independently. Fortunately, we found that a promising gene drive target in Anopheles gambiae is highly conserved in An. funestus. These insights will enable more strategic insecticide usage and gene drive deployment, supporting malaria elimination.

Members of the Anopheles gambiae complex, such as Anopheles gambiae sensu stricto (An. gambiae s.s.), Anopheles coluzzii and Anopheles arabiensis, are among the key malaria vectors in sub-Saharan Africa. These species are often abundant in areas of intense rice and maize farming with temporary water pools reflecting the dependence of their larvae on the pollen shed in such pools as food. In this study we explored the oviposition preference of wild-caught gravid An. arabiensis in response to maize and rice pollen in artificial aquatic habitats in a semi-field system. Twelve experimental breeding habitats were established in each of the two large compartments of a semi-field system. Rice or maize pollen was added into eight randomly selected habitats in eachcompartment; the remaining four habitats of each compartment were used as control habitats without pollens. In the first experiment, 40 gravid An. arabiensis were released in each compartment and left overnight to choose egg-laying habitats, following which the eggs were sampled and counted. The second experiment differed from the first experiment only in that the counted eggs were returned to the respective habitat where the development of the resultant larvae was monitored and recorded until pupation. Pollen types strongly affected the oviposition behaviour of gravid An. arabiensis. Females preferred to lay eggs in habitats with rice pollen on the water surface over those with maize pollen, and in habitats with maize pollen on the water surface over pollen-less controls. The development of larvae was significantly affected by the type of pollen in the habitats. The highest total number of An. arabiensis offspring were produced in habitats with rice pollen compared to those with maize pollen and no pollen. However, larval development success was comparatively lower in habitats containing rice pollen than those with maize pollen and no pollen, suggesting that the habitats with rice pollen were overcrowded. This study demonstrates that pollen types on the surface of aquatic habitats influence the oviposition site selection behaviour of gravid An. arabiensis and has carry-over effect on the developmental success of their offspring.

Population genetic analysis of mosquitoes is important for understanding the distribution of insecticide resistance alleles, devising sustainable control approaches, and understanding how vector populations are structured in space. Anopheles funestus is the dominant malaria vector in most parts of East and Southern Africa. To better understand its population genetic structure in Tanzania, we sequenced the genomes of 334 individual An. funestus mosquitoes from 11 regions across the country. Signs of reduced migration between western and eastern cohorts across the semi-arid central region containing the Rift Valley suggest a partial barrier to gene flow between these populations. This was evidenced by population structure between the eastern and western cohorts, as well as asynchronous selective sweeps and copy number variant profiles at the Cyp9k1 gene and Cyp6p gene cluster. Eastern cohorts, despite having less diversity and greater inbreeding, also share genetic histories characterized by low genome-wide Fst values with those in the west. This suggests that the barrier to gene flow is porous and likely represents continuous spatial structure rather than a complete barrier to migration. The observed population disconnectedness should be considered for insecticide deployment, resistance management, and the rollout of novel genetic-based vector control approaches. These findings provide the most detailed study of Tanzanian An. funestus population structure and resistance genetics to date. Future research should examine the epidemiological relevance of this partial discontinuity in gene flow and whether these populations have different malaria transmission abilities.

Population genetic analysis of mosquitoes is becoming increasingly important for understanding the distribution of insecticide resistance alleles, devising sustainable insecticide-based vector control approaches, and how malaria vector populations are structured in space. Anopheles funestus is the dominant malaria vector in Tanzania and most parts of East and Southern Africa. To better understand its population genomic structure in Tanzania, we sequenced the genomes of 334 individual An. funestus mosquitoes from 11 administrative regions. We found two genetically differentiated populations; one inland and at high altitude (found in Katavi, Kagera, Kigoma, and Mwanza) and a second coastal, at low altitude (found in Pwani, Morogoro, Tanga, Ruvuma, Mtwara, Dodoma, and Lindi), with differences in genetic diversity and inbreeding. We found asynchronous selective sweeps, associated with insecticide resistance phenotypes, at the Cyp9k1 gene, and Cyp6p gene cluster, with distinct copy number-variant profiles between the coastal and inland populations. These results suggest that inland and coastal An. funestus populations have divergent histories, with the arid, central region of Tanzania, which also contains the Rift Valley being a possible barrier to gene flow. Such population disconnectedness should be considered for insecticide deployment, resistance management, and the rollout of novel genetic-based vector control approaches. These findings provide the most detailed study of Tanzanian An. funestus population structure and resistance genetics to date. Future research should examine the epidemiological relevance of this discontinuity in gene flow and whether these populations have different malaria transmission abilities.

Vector-borne diseases, particularly arboviral diseases transmitted by mosquitoes (e.g. dengue, Zika and chikungunya), have (re)emerged globally with increasing prevalence and severity. Climatic and environmental changes have resulted in significant expansion of the geographical distribution of Aedes mosquito vectors to unprecedented levels, creating optimal conditions for their introduction and establishment in new areas, especially in Africa. The prevention of Aedes-borne diseases relies heavily on controlling vector populations. However, the global resurgence of dengue underscores the limitations of current vector control tools in preventing epidemics, highlighting the urgent need for affordable, scalable and community-based vector control measures to address Aedes-borne diseases and urban mosquito vectors (e.g. Aedes spp. and Anopheles stephensi), with the overall aim to improve public health and well-being. In this report, we summarize the main outcomes of the "International conference on advances in surveillance and control methods for Aedes-borne diseases and urban vectors" held in Dar es Salaam, Tanzania, 26-28 August 2024. The conference aimed to facilitate knowledge exchange, promote collaborative research and drive innovation in the surveillance and control of Aedes-borne diseases in Africa. Key objectives included reviewing the performance of new tools and technologies for Aedes control, and fostering inter-sectoral and international collaborations to strengthen public health measures against mosquito-borne diseases. The event was attended by more than 200 participants from 20 nationalities/countries and was streamed live online, with 321 virtual accesses recorded during the 3-day event.

Following the rapid scale-up of long-lasting insecticidal nets (LLINs) in 2008 across the Kilombero Valley of southern Tanzania, Anopheles gambiae Giles, a highly efficient and human-specialized malaria vector, essentially disappeared within two years and has rarely been detected since. However, an ecological study of its sibling species within the An. gambiae complex, namely An. arabiensis Patton and An. quadriannulatus Theobald, in an area spanning human settlements and conserved wilderness, nevertheless detected sparse, highly focal populations of An. gambiae . Out of 4,704 An. gambiae complex specimens collected, only 10 were identified as nominate An. gambiae by polymerase chain reaction. Seven of these were captured at three surveyed fishing camps inside a Wildlife Management Area (WMA), while none were caught in five established villages west of the WMA or the national park to the east. Two of the other three were found among scattered farming settlements along the edge of the WMA. The final individual was caught in a near-natural area deep inside the WMA, but even this site was near small transient homesteads. Poisson regression modelling confirmed that capture rates at fishing camps were higher than in the peripheral settlements (Relative Rate \[RR\] \[95% Confidence Interval (CI)\] = 0.088 [0.011, 0.695], P = 0.021) or conserved natural areas (RR [95% CI] = 0.043 [0.003, 0.495], P = 0.012). Conservative estimates put the mean standing populations at each of the three fishing camps between 26 and 41 females per settlement. The absence of An. gambiae from well-conserved areas without resident humans aligns with its anthropophagic nature and dependency on human hosts. Residual An. gambiae populations persisting among frontier communities appear linked to locally common, livelihood-related nocturnal activities that preclude the practical use of LLINs, specifically fishing and guarding crops against wildlife. The continued presence of this previously important species in these ecological niches, where local livelihoods apparently undermine high LLIN coverage, shows persistence under sustained, partial insecticide pressure. This could lead to the re-emergence of this vector through the gradual evolution of resistance. However, their sparse and focal distribution suggests that new supplementary interventions, such as transfluthrin emanators, might effectively eliminate these remaining refuge populations. ### Competing Interest Statement The authors have declared no competing interest. AXA Research Fund, https://ror.org/02zxqxw53 Irish Aid, IA-TAN/2022/144

As most malaria parasites of humans are strict anthroponoses, mosquito preference for human blood strongly influences transmission intensity and intervention strategy. Here, retrospective analyses of observational entomological data assessed the attraction of Anopheles arabiensis and Anopheles quadriannulatus (Diptera: Culicidae) to humans by comparing their abundance in larval and adult samples collected across an ecologically heterogeneous landscape in southern Tanzania. Surveys of mosquito larvae and adults were conducted across a landscape mosaic of different habitat types, with a gradient of land use practices ranging from comprehensive conversion to agriculture and human settlement through to essentially intact natural ecosystems inside well‐protected conservation areas. Larvae were collected from all water bodies within a 2 km radius of each of 40 mobile camping locations, while adults were surveyed using four light traps and one interception netting barrier trap at each transient camp. Light traps were placed at defined locations, specifically beside a human‐occupied tent, near the camp, in a nearby streambed, and in an open natural glade, while the barrier trap was also placed in an open natural glade. Almost all adult Anopheles gambiae complex mosquitoes caught were unfed and presumably host‐seeking. Breaking this complex down by sibling species, two to four times more An. arabiensis were caught in the light traps placed beside human‐occupied tents, although barrier traps achieved somewhat higher capture rates again. In contrast, An. quadriannulatus catches were consistently low across all traps, even in wild areas where it dominated larval populations, but were highest in open glades away from the camp location and activities. The overall proportion of An. arabiensis in adult collections was higher than in larval samples (98.7% vs. 78.3%, p < 0.0001) and adults caught beside human‐occupied tents had 20 times higher odds of being An. arabiensis , rather than An. quadriannulatus . Similarly, the barrier trap placed away from the camp, but frequently visited by human researchers, exhibited 22‐fold enrichment of An. arabiensis . These results confirm strong attraction of An. arabiensis to humans, contrasting with complete non‐responsiveness of the non‐vector An. quadriannulatus . Light traps beside human‐occupied tents efficiently capture anthropophagic mosquitoes outdoors, suggesting those occupants act as de facto bait hosts. In contrast, traps farthest from people give apparently unbiased representations of larval population composition, albeit with very low efficiency. However, frequent collector visits to netting barriers appear to attract anthropophagic mosquitoes, turning them into human‐baited traps in practical terms.

Abstract Background Members of the Anopheles gambiae complex are major malaria vectors in sub-Saharan Africa. Their larval stages inhabit a variety of aquatic habitats in which, under natural circumstances, they are preyed upon by different taxa of aquatic macroinvertebrate predators. Understanding the potential impact of predators on malaria vector larval population dynamics is important for enabling integrated local mosquito control programmes with a stronger emphasis on biocontrol approaches. This study experimentally evaluated the predation efficacy and foraging strategy of three common aquatic macroinvertebrate predators of An. gambiae, diving beetles (Coleoptera), backswimmers (Hemiptera), and dragonfly nymphs (Odonata) in a semi-field system in South-Eastern Tanzania. Methods An array of alternating small and large basins used as aquatic habitats was created in two compartments of a semi-field system and filled with well water. Field-collected adult diving beetles, backswimmers or dragonfly nymphs were randomly assigned to these habitats and Anopheles arabiensis larvae were added as prey in half of the habitats. The number of mosquito larvae consumed, predator mobility across habitats and mortality were recorded at 24, 48 and 72 h. Results The presence of An. gambiae larvae in habitats significantly increased the survival of backswimmer and dragonfly nymphs, which are not mobile. In contrast, diving beetles survived well under any initial condition by preferentially flying away from habitats without prey to nearby larger habitats with prey. The larval predation rates of predacious diving beetle, backswimmer and dragonfly nymphs were stable over time at a mean of 3.2, 7.0 and 9.6 larvae consumed each day. Conclusion This study demonstrates that aquatic macroinvertebrate predators display adaptive foraging behaviour in response to prey presence and aquatic habitat size. It also confirms the ability of these predators to significantly reduce An. gambiae larval densities in aquatic habitats, thus their potential for consideration as additional biocontrol tools for mosquito population reduction.