Small dams drive Anopheles abundance during the dry season in a high malaria burden area of Malawi.

This study explores the influence of small dams on the exposure to malaria vectors during the dry season in Kasungu district, Malawi, an area recently identified as high priority for malaria interventions by the National Malaria Control Programme. Small dam impoundments provide communities with a continuous supply of water for domestic and agricultural activities across sub-Saharan Africa and are considered vital to food security and climate change resilience. However, these permanent water bodies also create ideal breeding sites for mosquitoes in typically arid landscapes. The study focuses on a specific dam impoundment and its vicinity, aiming to assess its spatial and temporal influence on indoor vector densities. From May to August 2021, CDC light traps were used to measure indoor mosquito densities for two consecutive nights per month in three communities located at increasing distances from the dam (0, ~1 and ~2 km). Simultaneously, drone imagery was captured for each community, enabling the identification of additional standing water within approximately 400 m of selected households. Larval sampling was carried out within the impoundment periphery and in additional water bodies identified in the drone imagery. Generalised linear mixed models (GLMMs) were employed to analyse the indoor Anopheles abundance data, estimating the effects of household structure (open/closed eaves), month, temperature and water proximity on malaria vector exposure. Throughout 685 trapping nights, a total of 1256 mosquitoes were captured, with 33% (412) being female Anopheles. Among these, 91% were morphologically identified as Anopheles funestus s.l., and 5% as Anopheles gambiae s.l. Catches progressively decline in each consecutive trapping month as the environment became drier. This decline was much slower in Malangano, the community next to the dam, with abundance being notably higher in June and July. Further, the majority of An. gambiae s.l. were caught in May, with none identified in July and August. Anopheles larvae were found both in the impoundment and other smaller water bodies such as irrigation wells in each survey month; however, the presence of these smaller water bodies did not have a significant impact on adult female mosquito catches in the GLMM. The study concludes that proximity to the dam impoundment was the primary driver of differences between survey communities with the abundance in Chikhombwe (~1 km away) and Chiponde (~2 km away) being 0.35 (95% confidence interval [CI], 0.19-0.66) and 0.28 (95% CI, 0.16-0.47) lower than Malangano, respectively, after adjusting for other factors. These findings underscore the importance of targeted interventions, such as larval source management or housing improvements, near small dams to mitigate malaria transmission risks during the dry season. Further research is needed to develop cost-effective strategies for vector control within and around these impoundments.

Fine-scale mapping of urban malaria exposure under data scarcity: an approach centred on vector ecology.

BACKGROUND: Although malaria transmission has experienced an overall decline in sub-Saharan Africa, urban malaria is now considered an emerging health issue due to rapid and uncontrolled urbanization and the adaptation of vectors to urban environments. Fine-scale hazard and exposure maps are required to support evidence-based policies and targeted interventions, but data-driven predictive spatial modelling is hindered by gaps in epidemiological and entomological data. A knowledge-based geospatial framework is proposed for mapping the heterogeneity of urban malaria hazard and exposure under data scarcity. It builds on proven geospatial methods, implements open-source algorithms, and relies heavily on vector ecology knowledge and the involvement of local experts. METHODS: A workflow for producing fine-scale maps was systematized, and most processing steps were automated. The method was evaluated through its application to the metropolitan area of Dakar, Senegal, where urban transmission has long been confirmed. Urban malaria exposure was defined as the contact risk between adult Anopheles vectors (the hazard) and urban population and accounted for socioeconomic vulnerability by including the dimension of urban deprivation that is reflected in the morphology of the built-up fabric. Larval habitat suitability was mapped through a deductive geospatial approach involving the participation of experts with a strong background in vector ecology and validated with existing geolocated entomological data. Adult vector habitat suitability was derived through a similar process, based on dispersal from suitable breeding site locations. The resulting hazard map was combined with a population density map to generate a gridded urban malaria exposure map at a spatial resolution of 100 m. RESULTS: The identification of key criteria influencing vector habitat suitability, their translation into geospatial layers, and the assessment of their relative importance are major outcomes of the study that can serve as a basis for replication in other sub-Saharan African cities. Quantitative validation of the larval habitat suitability map demonstrates the reliable performance of the deductive approach, and the added value of including local vector ecology experts in the process. The patterns displayed in the hazard and exposure maps reflect the high degree of heterogeneity that exists throughout the city of Dakar and its suburbs, due not only to the influence of environmental factors, but also to urban deprivation. CONCLUSIONS: This study is an effort to bring geospatial research output closer to effective support tools for local stakeholders and decision makers. Its major contributions are the identification of a broad set of criteria related to vector ecology and the systematization of the workflow for producing fine-scale maps. In a context of epidemiological and entomological data scarcity, vector ecology knowledge is key for mapping urban malaria exposure. An application of the framework to Dakar showed its potential in this regard. Fine-grained heterogeneity was revealed by the output maps, and besides the influence of environmental factors, the strong links between urban malaria and deprivation were also highlighted.

Predation risk effects on larval development and adult life of Aedes aegypti mosquito.

Biological control is one of the methods available for control of Aedes aegypti populations. We used experimental microcosms to evaluate the effects of actual predation and predation risk by dragonfly larvae (Odonata) on larval development, adult longevity, and adult size of Ae. aegypti. We used six treatments: control, removal, variable density cues (Cues VD), fixed density cues (Cues FD), variable density predator (Predator VD), and fixed density predator (Predator FD) (n = 5 each). Predator treatments received one dragonfly larva. Cue treatments were composed of crushed Ae. aegypti larvae released into the microcosm. For the FD treatments, we maintained a larval density of 200 individuals. The average mortality of Ae. aegypti larvae in the Predator VD treatment was used as the standard mortality for the other treatments. Mosquitoes from the Predator VD and Cues VD treatments developed faster, and adults were larger and had greater longevity compared to all other treatments, likely due to the higher food availability from larval density reduction. High larval density negatively affected larval developmental time, adult size, and longevity. Males were less sensitive to density-dependent effects. Results from this study suggest that the presence of predators may lead to the emergence of adult mosquitoes with greater fitness, causing an overall positive effect on Ae. aegypti population growth rates.

Effect of ultraviolet LED and trap height on catches of host-seeking anopheline mosquitoes by using a low-cost passive light trap in northeast Brazil.

Light traps have been widely used for monitoring malaria vectors, although drawbacks remain. In this context, new tools and attractants are always becoming available to perform monitoring tasks, like the Silva trap, a passive and low-cost LED-light trap for host-seeking anopheline mosquitoes. In this work, the effectiveness of the Silva trap by using UV-LED and at different heights as well as a comparison with the conventional CDC-type (HP) light trap was studied. A total of 9009 mosquitoes and nine species were caught, Anopheles triannulatus, An. argyritarsis, and An. goeldii being the most frequent species. The green (520 nm) and blue (470 nm) LEDs attracted almost equal numbers of anopheline mosquitoes, but UV LEDs (395 nm) attracted a significantly lower number of individuals (Kruskal-Wallis = 19.68, P = 0.0001). Even with the predominance of mosquitoes trapped at the height of 1.5 m, no significant statistical difference was found among the four heights tested (0.5 m; 1.0 m; 1.5 m; 2.0 m). Green-baited Silva traps collected significantly more individuals than incandescent-baited CDC-type traps (U = 60.5; P = 0.0303). LEDs have been useful as light sources for attracting insect vectors and together with a low-cost trap, as the Silva trap, a feasible alternative to conventional trap-based monitoring Anopheles mosquitoes that can be implemented in the field.

Prioritizing management of high-risk routes and ports by vessel type to improve marine biosecurity efforts.

The shipping industry constitutes the main vector of marine bioinvasions. Over 90,000 vessels world-wide create a highly complex shipping network that requires appropriate management tools. Here we characterized a novel vessel category, Ultra Large Container Vessels (ULCV), in terms of potential contribution to the dispersal of Non-Indigenous Species (NIS) in comparison to smaller vessels traveling similar routes. Such approach is essential for providing precise information-based risk analysis necessary to enforce biosecurity regulations and reduce the adverse global effects of marine NIS. We used Automatic Identification System (AIS) based websites to extract shipping data that will enable us to test for differences in two vessel behaviors linked to NIS dispersal: port visit durations and voyage sailing times. We then examined the geographic spread of ULCVs and small vessels, quantifying the accumulation of new port visits, countries, and ecoregions for each vessel category. Finally, Higher Order Network (HON) analysis revealed emergent patterns within shipping traffic, species flow, and invasion risk networks of these two categories. Compared to the smaller vessels, ULCVs spent significantly longer time in 20% of the ports and were more geographically constrained, with fewer port visits, countries, and regions. HON analysis revealed that the ULCV shipping species flow and invasion risk networks were more similar to each other than to those of the smaller vessels. However, HON port importance shifts were discernible for both vessel categories, with major shipping hubs not necessarily being major invasion hubs. Overall, compared to smaller vessels, ULCVs behave differently in ways that potentially increase biofouling risk, albeit in a smaller set of ports. Future studies using HON analysis of other dispersal vectors appears critical for prioritizing management of high-risk routes and ports.

Using ecological observations to improve malaria control in areas where Anopheles funestus is the dominant vector.

The most important malaria vectors in sub-Saharan Africa are Anopheles gambiae, Anopheles arabiensis, Anopheles funestus, and Anopheles coluzzii. Of these, An. funestus presently dominates in many settings in east and southern Africa. While research on this vector species has been impeded by difficulties in creating laboratory colonies, available evidence suggests it has certain ecological vulnerabilities that could be strategically exploited to greatly reduce malaria transmission in areas where it dominates. This paper examines the major life-history traits of An. funestus, its aquatic and adult ecologies, and its responsiveness to key interventions. It then outlines a plausible strategy for reducing malaria transmission by the vector and sustaining the gains over the medium to long term. To illustrate the propositions, the article uses data from south-eastern Tanzania where An. funestus mediates over 85% of malaria transmission events and is highly resistant to key public health insecticides, notably pyrethroids. Both male and female An. funestus rest indoors and the females frequently feed on humans indoors, although moderate to high degrees of zoophagy can occur in areas with large livestock populations. There are also a few reports of outdoor-biting by the species, highlighting a broader range of behavioural phenotypes that can be considered when designing new interventions to improve vector control. In comparison to other African malaria vectors, An. funestus distinctively prefers permanent and semi-permanent aquatic habitats, including river streams, ponds, swamps, and spring-fed pools. The species is therefore well-adapted to sustain its populations even during dry months and can support year-round malaria transmission. These ecological features suggest that highly effective control of An. funestus could be achieved primarily through strategic combinations of species-targeted larval source management and high quality insecticide-based methods targeting adult mosquitoes in shelters. If done consistently, such an integrated strategy has the potential to drastically reduce local populations of An. funestus and significantly reduce malaria transmission in areas where this vector species dominates. To sustain the gains, the programmes should be complemented with gradual environmental improvements such as house modification to maintain biting exposure at a bare minimum, as well as continuous engagements of the resident communities and other stakeholders.

Evolutionary consequences of vector-borne transmission: how using vectors shapes host, vector and pathogen evolution.

Transmission mode is a key factor that influences host­parasite coevolution. Vector-borne pathogens are among the most important disease agents for humans and wildlife due to their broad distribution, high diversity, prevalence and lethality. They comprise some of the most important and widespread human pathogens, such as yellow fever, leishmania and malaria. Vector-borne parasites (in this review, those transmitted by blood-feeding Diptera) follow unique transmission routes towards their vertebrate hosts. Consequently, each part of this tri-partite (i.e. parasite, vector and host) interaction can influence co- and counter-evolutionary pressures among antagonists. This mode of transmission may favour the evolution of greater virulence to the vertebrate host; however, pathogen­vector interactions can also have a broad spectrum of fitness costs to the insect vector. To complete their life cycle, vector-borne pathogens must overcome immune responses from 2 unrelated organisms, since they can activate responses in both vertebrate and invertebrate hosts, possibly creating a trade-off between investments against both types of immunity. Here, we assess how dipteran vector-borne transmission shapes the evolution of hosts, vectors and the pathogens themselves. Hosts, vectors and pathogens co-evolve together in a constant antagonistic arms race with each participant's primary goal being to maximize its performance and fitness.

Big Baby, Little Mother: Tsetse Flies Are Exceptions to the Juvenile Small Size Principle.

While across the animal kingdom offspring are born smaller than their parents, notable exceptions exist. Several dipteran species belonging to the Hippoboscoidea superfamily can produce offspring larger than themselves. In this essay, the blood-feeding tsetse is focused on. It is suggested that the extreme reproductive strategy of this fly is enabled by feeding solely on highly nutritious blood, and producing larval offspring that are soft and malleable. This immense reproductive expenditure may have evolved to avoid competition with other biting flies. Tsetse also transmit blood-borne parasites that cause the fatal diseases called African trypanosomiases. It is discussed how tsetse life history and reproductive strategy profoundly influence the type of vector control interventions used to reduce fly populations. In closing, it is argued that the unusual life history of tsetse warrants their preservation in the areas where human and animal health is not threatened.

Two new phlebotomine sandflies (Diptera: Psychodidae) from the forest edge in Madagascar: the anthropophilic Phlebotomus artemievi sp. nov. and Sergentomyia maroantsetra ensis sp. nov.

A few data are related to the anthropophily of Malagasy Phlebotomine sandflies. Prior studies focussed mainly to inventories and description of new species. Our goal was to emphasize the anthropophily of Malagasy Phlebotomine sandflies. We worked in the Makira region, using two simultaneous methods: human landing catches (HLC) and CDC light traps. We collected sandflies in three rural communities adjacent to the Makira Natural Park. In each community, three different biotopes were sampled: within community settlements; at the edge of forest, typically in agricultural land; and within the forest. We collected 61 sandflies belonging to two new species presently described: Phlebotomus artemievi sp. nov. and Sergentomyia maroantsetraensis sp. nov. These sandflies were caught exclusively in the forest edge biotope. None were captured within communities or within forests. HLC provided 97% of the collected sandflies, corresponding to a human-biting rate of 15 females per human per night. CDC provided only two females. Ph. artemievi sp. nov. was predominantly captured by HLC and appears to be highly anthropophilic. Here, we update the behavioural ecology of sandflies and describe two new species. Further research is required to understand their vector competence and their ability to transmit arboviruses and other pathogens such as Leishmania.

Synergisms in Science: Climate Change and Integrated Pest Management Through the Lens of Communication-2019 Student Debates.

Every year, the Student Debates Subcommittee (SDS) of the Student Affairs Committee (SAC) for the annual Entomological Society of America (ESA) meeting organizes the Student Debates. This year, the SAC selected topics based on their synergistic effect or ability to ignite exponential positive change when addressed as a whole. For the 2019 Student Debates, the SAC SDS identified these topic areas for teams to debate and unbiased introduction speakers to address: 1) how to better communicate science to engage the public, particularly in the area of integrated pest management (IPM), 2) the influential impacts of climate change on agriculturally and medically relevant insect pests, and 3) sustainable agriculture techniques that promote the use of IPM to promote food security. Three unbiased introduction speakers gave a foundation for our audience to understand each debate topic, while each of six debate teams provided a strong case to support their stance or perspective on a topic. Debate teams submitted for a competitive spot for the annual ESA Student Debates and trained for the better part of a year to showcase their talents in presenting logical arguments for a particular topic. Both the debate teams and unbiased introduction speakers provided their insight toward a better understanding of the complexities of each topic and established a foundation to delve further into the topics of science advocacy and communication, climate change, and the many facets of integrated pest management.

Comparative evaluation of anopheline sampling methods in three localities in Indonesia.

BACKGROUND: The effectiveness of vector control efforts can vary based on the interventions used and local mosquito behaviour and adaptability. In many settings, biting patterns of Anopheles mosquitoes can shift in response to interventions targeting indoor-biting mosquitoes, often resulting in higher proportions of mosquitoes feeding outside or at times when people are not protected. These behaviourally resistant mosquitoes have been shown to sustain residual malaria transmission and limit control efforts. Therefore, it is important to accurately sample mosquitoes to understand their behaviour. METHODS: A variety of traps were evaluated in three geographically diverse sites in malaria-endemic Indonesia to investigate local mosquito feeding behaviour and determine effective traps for surveillance. RESULTS: Eight traps were evaluated in three sites: Canti village, Lampung, Kaliharjo village, Purworejo, and Saketa village, Halmahera, Indonesia, including the gold standard human landing collection (HLC) and a variety of traps targeting host-seeking and resting mosquitoes both indoors and outdoors. Trapping, using indoor and outdoor HLC, the Ifakara tent trap C, goat and human-occupied tents, resting pots and boxes, and CDC miniature light traps was conducted for 16 nights in two sites and 8 nights in a third site, using a Latin square design. Trap efficacy varied by site, with outdoor HLC yielding the highest catch rates in Canti and Kaliharjo and a goat-baited tent trap proving most effective in Saketa. In Canti village, anthropophilic Anopheles sundaicus were caught indoors and outdoors using HLCs, peaking in the early morning. In Kaliharjo, a variety of mosquitoes were caught, mostly outdoors throughout the night. HLC was ineffective in Saketa, the only site where a goat-baited tent trap was tested. This trap was effective in catching zoophilic vectors outdoors before midnight. CONCLUSIONS: Different trapping methods were suitable for different species, likely reflecting differences in behaviour among species. The three villages, each located on a different island in the Indonesian archipelago, contained mosquito populations with unique behaviours. These data suggest that the effectiveness of specific vector monitoring and control measures may vary by location.

Household-level and surrounding peri-domestic environmental characteristics associated with malaria vectors Anopheles arabiensis and Anopheles funestus along an urban-rural continuum in Blantyre, Malawi.

BACKGROUND: Malaria is increasing in some recently urbanized areas that historically were considered lower risk. Understanding what drives urban transmission is hampered by inconsistencies in how "urban" contexts are defined. A dichotomized "urban-rural" approach, based on political boundaries may misclassify environments or fail to capture local drivers of risk. Small-scale agriculture in urban or peri-urban settings has been shown to be a major risk determinant. METHODS: Household-level Anopheles abundance patterns in and around Malawi's commercial capital of Blantyre (~ 1.9 M pop.) were analysed. Clusters (N = 64) of five houses each located at 2.5 km intervals along eight transects radiating out from Blantyre city centre were sampled during rainy and dry seasons of 2015 and 2016. Mosquito densities were measured inside houses using aspirators to sample resting mosquitoes, and un-baited CDC light traps to sample host seeking mosquitoes. RESULTS: Of 38,895 mosquitoes captured, 91% were female and 87% were Culex spp. Anopheles females (N = 5058) were primarily captured in light traps (97%). Anopheles abundance was greater during rainy seasons. Anopheles funestus was more abundant than Anopheles arabiensis, but both were found on all transects, and had similar associations with environmental risk factors. Anopheles funestus and An. arabiensis females significantly increased with distance from the urban centre, but this trend was not consistent across all transects. Presence of small-scale agriculture was predictive of greater Anopheles spp. abundance, even after controlling for urbanicity, number of nets per person, number of under-5-year olds, years of education, and season. CONCLUSIONS: This study revealed how small-scale agriculture along a rural-to-urban transition was associated with An. arabiensis and An. funestus indoor abundances, and that indoor Anopheles density can be high within Blantyre city limits, particularly where agriculture is present. Typical rural areas with lower house density and greater distance from urban centres reflected landscapes more suitable for Anopheles reproduction and house invasion. However, similar characteristics and elevated Anopheles abundances were also found around some houses within the city limits. Thus, dichotomous designations of "urban" or "rural" can obscure important heterogeneity in the landscape of Plasmodium transmission, suggesting the need for more nuanced assessment of urban malaria risk and prevention efforts.

Mosquito responses to trait- and density-mediated interactions of predation.

Mosquito and predatory larvae often share the same habitat. Predators may influence mosquito prey populations through both lethal effect and non-lethal pathways. A series of experimental manipulations were used to distinguish between lethal (density-mediated interaction) and non-lethal (trait-mediated interaction) effects in a model system comprised of invasive prey mosquito, Aedes aegypti, and a predatory mosquito Toxorhynchites rutilus. Treatments with predators present or manipulations mimicking daily mortality (density reduction) reduced developmental time and recruitment to the adult stage. Daily records of adult survival of A. aegypti showed that exposure to predators during the juvenile stage shortened the lifespan of adults. This was also observed in treatments, where A. aegypti were replaced at the rate of consumption by T. rutilus. In contrast, numerical reductions in A. aegypti that mimicked daily rate of predation led to adults with the longest lifespan. These observations suggest strong effects of density and trait-mediated interactions in the influence of predators on mosquito biology relevant to their ability to transmit pathogens. These results have potentially important implications for disease control strategies. The primary approach to reduce risk of mosquito-borne diseases is through population reduction of the vectors. We show an unanticipated benefit of biological control by predation for the control of juvenile stages of mosquitoes. Specifically, mosquitoes that are exposed to predators but survive to adulthood will have compromised life expectancy, a key parameter in determining risk of disease transmission.

Borrelia burgdorferi in small mammal reservoirs in Kentucky, a traditionally non-endemic state for Lyme disease.

The incidence of tick-borne zoonoses such as Lyme disease has steadily increased in the southeastern United States. Southeastern states accounted for 1500 of over 28,000 confirmed cases of Lyme disease reported in the United States during 2015. Borrelia burgdorferi, the etiologic agent of Lyme disease, is maintained in small mammal reservoirs and vectored to new hosts by ixodid ticks. This study examined ecological relationships of the B. burgdorferi/vector/reservoir system in order to understand the dynamics of Lyme disease risk in Kentucky. Small mammals were captured using live traps from November 2014 to October 2015. Ticks were removed and blood and tissue collected from small mammals were screened for B. burgdorferi DNA by PCR with primers specific to the OspA gene. Prevalence of B. burgdorferi (21.8%) in Kentucky small mammals was comparable to the lowest recorded prevalence in regions where Lyme disease is endemic. Moreover, infestation of small mammals by Ixodes scapularis, the primary vector of B. burgdorferi, was rare, while Dermacentor variabilis comprised the majority of ticks collected. These findings provide ecological insight into the relative paucity of Lyme disease in Kentucky.

Change in Anopheles richness and composition in response to artificial flooding during the creation of the Jirau hydroelectric dam in Porto Velho, Brazil.

BACKGROUND: Anopheles mosquitoes are the only vectors of human malaria. Anopheles species use standing water as breeding sites. Human activities, like the creation of an artificial lake during the implementation of hydroelectric power plants, lead to changes in environmental characteristics and, therefore, may changes the species richness and composition of Anopheles mosquitoes. The aim of the present study was to verify whether or not there is an association between the artificial flooding resulting from the construction of the Jirau hydroelectric power plant, and the richness and composition of anophelines. METHODS: Mosquitoes samples were obtained monthly from the Jirau hydroelectric power plant area located at Porto Velho, Rondônia State, using Human Landing Catch (06:00-10:00 PM). Mosquitoes collected were transported to Laboratório de Entomologia Médica FIOCRUZ-RO where they were identified until species using dichotomous key. RESULTS: A total of 6347 anophelines belonging to eight different species were collected. The anophelines species richness was significantly lower during the first flooding stage. Differences in anophelines species composition were found when comparing the first flooding stage with the other stages. Furthermore, the mean number of Anopheles darlingi, the main vector of malaria in the region, increases during the first and the third flooding stages. CONCLUSIONS: The continual monitoring of these vectors during the late operational phase may be useful in order to understand how anophelines will behave in this area.

Host attraction and biting behaviour of Anopheles mosquitoes in South Halmahera, Indonesia.

BACKGROUND: Indonesia is home to a variety of malaria vectors whose specific bionomic traits remain largely uncharacterized. Species-specific behaviours, such as host feeding preferences, impact the dynamics of malaria transmission and the effectiveness of vector control interventions. METHODS: To examine species-specific host attraction and feeding behaviours, a Latin square design was used to compare Anopheles mosquitoes attracted to human, cow, and goat-baited tents. Anopheles mosquitoes were collected hourly from the inside walls of each baited tent. Species were morphologically and then molecularly identified using rDNA ITS2 sequences. The head and thorax of individual specimens were analysed for Plasmodium DNA using PCR. Bloodmeals were identified using a multiplex PCR. RESULTS: A total of 1024, 137, and 74 Anopheles were collected over 12 nights in cow, goat, and human-baited tents, respectively. The species were identified as Anopheles kochi, Anopheles farauti s.s., Anopheles hackeri, Anopheles hinesorum, Anopheles indefinitus, Anopheles punctulatus, Anopheles tessellatus, Anopheles vagus, and Anopheles vanus, many of which are known to transmit human malaria. Molecular analysis of blood meals revealed a high level of feeding on multiple host species in a single night. Anopheles kochi, An. indefinitus, and An. vanus were infected with Plasmodium vivax at rates comparable to primary malaria vectors. CONCLUSIONS: The species distributions of Anopheles mosquitoes attracted to human, goat, and cow hosts were similar. Eight of nine sporozoite positive samples were captured with animal-baited traps, indicating that even predominantly zoophilic mosquitoes may be contributing to malaria transmission. Multiple host feeding and flexibility in blood feeding behaviour have important implications for malaria transmission, malaria control, and the effectiveness of intervention and monitoring methods, particularly those that target human-feeding vectors.

Species Distribution Modelling of Aedes aegypti in two dengue-endemic regions of Pakistan.

OBJECTIVES: Statistical tools are effectively used to determine the distribution of mosquitoes and to make ecological inferences about the vector-borne disease dynamics. In this study, we utilised species distribution models to understand spatial patterns of Aedes aegypti in two dengue-prevalent regions of Pakistan, Lahore and Swat. Species distribution models can potentially indicate the probability of suitability of Ae. aegypti once introduced to new regions like Swat, where invasion of this species is a recent phenomenon. METHODS: The distribution of Ae. aegypti was determined by applying the MaxEnt algorithm on a set of potential environmental factors and species sample records. The ecological dependency of species on each environmental variable was analysed using response curves. We quantified the statistical performance of the models based on accuracy assessment and spatial predictions. RESULTS: Our results suggest that Ae. aegypti is widely distributed in Lahore. Human population density and urban infrastructure are primarily responsible for greater probability of mosquito occurrence in this region. In Swat, Ae. aegypti has clumped distribution, where urban patches provide refuge to the species in an otherwise hostile heterogeneous environment and road networks are assumed to have facilitated in passive-mediated dispersal of species. CONCLUSIONS: In Pakistan, Ae. aegypti is expanding its range northwards; this could be associated with rapid urbanisation, trade and travel. The main implication of this expansion is that more people are at risk of dengue fever in the northern highlands of Pakistan.

Behaviour and molecular identification of Anopheles malaria vectors in Jayapura district, Papua province, Indonesia.

BACKGROUND: Members of the Anopheles punctulatus group dominate Papua, Indonesia and Papua New Guinea (PNG), with a geographic range that extends south through Vanuatu. An. farauti and An. punctulatus are the presumed major vectors in this region. Although this group of species has been extensively studied in PNG and the southern archipelagoes within their range, their distribution, ecology and vector behaviours have not been well characterized in eastern Indonesia. METHODS: Mosquitoes were collected in five villages in Jayapura province, Papua, Indonesia using human-landing collections, animal-baited tents and backpack aspirators. Mosquitoes were morphologically typed and then molecularly distinguished based on ribosomal ITS2 sequences and tested for Plasmodium falciparum and P. vivax infection using circumsporozoite ELISA and PCR. RESULTS: The presence and vector status of An. farauti 4 in Papua, Indonesia is confirmed here for the first time. The data indicate that this species is entering houses at a rate that increases its potential to come into contact with humans and act as a major malaria vector. An. farauti 4 was also abundant outdoors and biting humans during early evening hours. Other species collected in this area include An. farauti 1, An. hinesorum, An. koliensis, An. punctulatus, and An. tessellatus. Proboscis morphology was highly variable within each species, lending support to the notion that this characteristic is not a reliable indicator to distinguish species within the An. punctulatus group. CONCLUSIONS: The vector composition in Papua, Indonesia is consistent with certain northern areas of PNG, but the behaviours of anophelines sampled in this region, such as early and indoor human biting of An. farauti 4, may enable them to act as major vectors of malaria. Presumed major vectors An. farauti and An. punctulatus were not abundant among these samples. Morphological identification of anophelines in this sample was often inaccurate, highlighting the importance of using molecular analysis in conjunction with morphological investigations to update keys and training tools.

Ecology of urban malaria vectors in Niamey, Republic of Niger.

BACKGROUND: Urbanization in African cities has major impact on malaria risk. Niamey, the capital of the Republic of Niger, is situated in the West African Sahel zone. The short rainy season and human activities linked with the Niger River influence mosquito abundance. This study aimed at deciphering the factors of distribution of urban malaria vectors in Niamey. METHODS: The distribution of mosquito aquatic stages was investigated monthly from December 2002 to November 2003, at up to 84 breeding sites, throughout Niamey. An exploratory analysis of association between mosquito abundance and environmental factors was performed by a Principal Component Analysis and confirmed by Kruskall-Wallis non-parametric test. To assess the relative importance of significant factors, models were built for Anopheles and Culicinae. In a second capture session, adult mosquitoes were collected weekly with pyrethrum sprays and CDC light-traps from June 2008 to June 2009 in two differentiated urban areas chosen after the study's first step. Members of the Anopheles gambiae complex were genotyped and Anopheles females were tested for the presence of Plasmodium falciparum circumsporozoite antigens using ELISA. RESULTS: In 2003, 29 % of 8420 mosquitoes collected as aquatic stages were Anopheles. They were significantly more likely to be found upstream, relatively close to the river and highly productive in ponds. These factors remained significant in regression and generalized linear models. The Culicinae were found significantly more likely close to the river, and in the main temporary affluent stream. In 2009, Anopheles specimens, including Anopheles gambiae s.l. (95 %), but also Anopheles funestus (0.6 %) accounted for 18 % of the adult mosquito fauna, with a large difference between the two sampled zones. Three members of the An. gambiae complex were found: Anopheles arabiensis, Anopheles coluzzii, and An. gambiae. Nineteen (1.3 %) out of 1467 females tested for P. falciparum antigen were found positive. CONCLUSION: The study provides valuable update knowledge on malaria vector ecology and distribution in Niamey. The identification of spatial and environmental risk factors could pave the way to larval source management strategy and allow malaria vector control to focus on key zones for the benefit of the community.

Selective Insecticide Applications Directed Against Triatoma infestans (Hemiptera: Reduviidae) Affected a Nontarget Secondary Vector of Chagas Disease, Triatoma garciabesi.

The control of nondomiciliated triatomine species adapted to peridomestic habitats represents a challenge because they are connected to sylvatic colonies, and pyrethroid insecticides have limited effects outdoors. The effects of residual insecticide spraying have rarely been assessed on secondary triatomines. Triatoma garciabesi (Carcavallo, Martinez, Cichero, Prosen & Ronderos, 1967) is a nontarget vector that inhabits the dry western Chaco region, and a member of the Triatoma sordida Stål 1859 complex. Little is known on the capacity of T. garciabesi to invade and establish viable domestic or peridomestic colonies, and on its response to residual insecticide sprays directed against Triatoma infestans Klug 1834. The presence and abundance of triatomines were assessed by timed manual collections annually or biannually (spring and fall) during 10 yr after a community-wide insecticide spraying campaign and selective insecticide sprays directed against T. infestans in a rural village of northwestern Argentina. T. garciabesi mainly occupied peridomestic habitats associated with chickens, and was unable to colonize human sleeping quarters. Trees with chickens occurred in nearly all houses and were infested in >25% of the occasions. The abundance of bugs at house-compound level was best explained by a generalized estimating equation model that included selective insecticide sprays during the previous semester (negative effects), chicken abundance (positive effects), seasonality, and their interactions. Our results suggest that insecticide applications targeting T. infestans affected the abundance of T. garciabesi, and reduced the likelihood of future infestation.