Mosquito Species Composition Research Articles

Anthropogenic landscape decreases mosquito biodiversity and drives malaria vector proliferation in the Amazon rainforest.

Inter-relationships among mosquito vectors, Plasmodium parasites, human ecology, and biotic and abiotic factors, drive malaria risk. Specifically, rural landscapes shaped by human activities have a great potential to increase the abundance of malaria vectors, putting many vulnerable people at risk. Understanding at which point the abundance of vectors increases in the landscape can help to design policies and interventions for effective and sustainable control. Using a dataset of adult female mosquitoes collected at 79 sites in malaria endemic areas in the Brazilian Amazon, this study aimed to (1) verify the association among forest cover percentage (PLAND), forest edge density (ED), and variation in mosquito diversity; and to (2) test the hypothesis of an association between landscape structure (i.e., PLAND and ED) and Nyssorhynchus darlingi (Root) dominance. Mosquito collections were performed employing human landing catch (HLC) (peridomestic habitat) and Shannon trap combined with HLC (forest fringe habitat). Nyssorhynchus darlingi abundance was used as the response variable in a generalized linear mixed model, and the Shannon diversity index (H’) of the Culicidae community, PLAND, and the distance house-water drainage were used as predictors. Three ED categories were also used as random effects. A path analysis was used to understand comparative strengths of direct and indirect relationships among Amazon vegetation classes, Culicidae community, and Ny. darlingi abundance. Our results demonstrate that Ny. darlingi is negatively affected by H´ and PLAND of peridomestic habitat, and that increasing these variables (one-unit value at β0 = 768) leads to a decrease of 226 (P < 0.001) and 533 (P = 0.003) individuals, respectively. At the forest fringe, a similar result was found for H’ (β1 = -218; P < 0.001) and PLAND (β1 = -337; P = 0.04). Anthropogenic changes in the Amazon vegetation classes decreased mosquito biodiversity, leading to increased Ny. darlingi abundance. Changes in landscape structure, specifically decreases in PLAND and increases in ED, led to Ny. darlingi becoming the dominant species, increasing malaria risk. Ecological mechanisms involving changes in landscape and mosquito species composition can help to understand changes in the epidemiology of malaria.

UPDATED COUNTY MOSQUITO SPECIES RECORDS FOR NORTHWEST FLORIDA

This report updates the mosquito species composition for Santa Rosa, Okaloosa, Walton, Holmes, Washington, Jackson, Calhoun, Liberty, Gadsden, Leon, Wakulla, Jefferson, Madison, and Taylor Counties, through collections made in a centralized surveillance program operated from 2002-2020 in northwest Florida. 91 county species records were documented. The most notable discoveries included finding Mansonia titillans (Walker) in eleven of the fourteen surveyed counties, Psorophora horrida (Dyar and Knab) in nine, Anopheles perplexens Ludlow in eight and Culex erraticus (Dyar and Knab) and Uranotaenia lowii Theobald in seven. Psorophora mathesoni Belkin and Heinemann and Aedes japonicus japonicus (Theobald) were found in six new counties. Culex pilosus (Dyar and Knab) was found solely in Calhoun and Liberty Cos., while Culex peccator Dyar and Knab and Culex tarsalis Coquillett were recovered in Calhoun Co. and Santa Rosa Co., respectively. Mansonia titillans, Cx. erraticus, Cx. tarsalis and Ae. j. japonicus are known arbovirus vectors, thus increasing the disease risk in this region.

Identification and seasonal distribution of mosquito species in Telangana state, India

An entomological study was conducted to determine species composition, relative abundance, and seasonal population fluctuation of mosquitoes. Thirty localities were randomly selected and sampled once in summer, monsoon and winter seasons for a period of three years. Adult mosquitoes were collected from in and around human dwellings and animal sheds using aspirator and flash light between 6 PM and 7:30 PM hrs and 06:00 AM and 7:00 AM hrs. Larvae were collected from ditches, rock pool and other domestic habitats, reared to formation of adults in the lab. A total of 18425 mosquitoes were collected. Five genera (Culex, Anopheles, Aedes, Mansonia and Armigeres) were found to be circulating. Further, with respect to habitat, more number of mosquitoes were observed around cattle sheds and houses. Culex quinquefasciatus occupies top place, followed by Aedes albopictus and Culex gelidus, Culex tritaeniorhynchus with respect to density, whereas Mansonia uniformis occupies last place. Culex quinquifasciatus is top again followed by Culex gelidus and Aedes albopictus, Mansonia uniformis is last again with respect to distribution. The vector species studied were Aedes aegypti, Aedes albopictus for chikungunya and dengue, Anopheles stephensi, Anopheles culicifacies for malaria, Culex tritaeniorhynchus for Japanese encephalitis and Culex quiquefasciatus for lymphatic filaria.

Dynamic Surveillance of Mosquitoes and Their Viromes in Wuhan During 2020

Objective: Mosquitoes are medically important arthropod vectors that harbor a variety of viruses. Geography and climate are known to be associated with variations in mosquito density, species and viromes. Our study investigated the dynamic changes in mosquito populations, species compositions and viromes in a regularly disinfected environment in Wuhan, China, during 2020. Methods: Traps were set in different mosquito habitats, including an urban residential area, two hospitals, a scenic area and a pig farm in a rural region between April and October of 2020. The collected mosquitoes were subjected to morphological identification, RT-qPCR and metagenomic sequencing. Results: A total of 2345 adult mosquitoes were collected. Culex mosquitoes were dominant in both urban regions (90.32%, 1538/1703) and the pig farm (54.98%, 353/642). In RT-qPCR screening, the prevalence of Banna virus was 15% and 3% in mosquitoes from the urban area and the pig farm, respectively, whereas no Japanese encephalitis virus was detected. Culex viromes showed dynamic changes during the collection period. Several mosquito-specific viruses, such as Culex flavivirus, Alphamesonivirus 1, Hubei mosquito virus 2 and Hubei mosquito virus 4, showed seasonal changes and unimodal increases or declines. Other mosquito-specific viruses, such as Wuhan mosquito virus 6, Hubei virga-like virus 2 and Zhejiang mosquito virus 3, were stable in all collected Culex and are potential members of the core viromes. Conclusion: This study improves understanding of the dynamic composition of mosquito species and the viromes that they carry, and provides useful information for guiding mosquito control and mosquito-borne disease prevention strategies.

The Mosquito Fauna (Diptera, Culicidae) of Belarus

Literary data on the fauna of mosquitoes (family Culicidae) in Belarus since the 1920s have been analyzed together with the original material. The fauna of Belarus comprises 41 mosquito species from 5 genera. Most species (26) belong to the genus Aedes while the genera Anopheles, Culiseta, Culex, and Coquillettidia are represented by 5, 5, 4, and 1 species, respectively. The mass species in the territory of Belarus are Aedes punctor (Kirby, 1837), A. communis (De Geer, 1776), A. cantans (Meigen, 1818), A. cinereus Meigen, 1818, and A. sticticus (Meigen, 1838). The species composition of mosquitoes in Minsk, Gomel, Vitebsk, and Brest provinces has been most completely studied, whereas the data on Mogilev and Grodno provinces are fragmentary, requiring further studies.

Impact of sugarcane irrigation on malaria vector Anopheles mosquito fauna, abundance and seasonality in Arjo-Didessa, Ethiopia

BackgroundDespite extensive irrigation development in Ethiopia, limited studies assessed the impact of irrigation on malaria vector mosquito composition, abundance and seasonality. This study aimed to evaluate the impact of sugarcane irrigation on species composition, abundance and seasonality of malaria vectors.MethodsAdult Anopheles mosquitoes were collected using CDC light traps from three irrigated and three non-irrigated clusters in and around Arjo-Didessa sugarcane irrigation scheme in southwestern Ethiopia. Mosquitoes were surveyed in four seasons: two wet and two dry, in 2018 and 2019. Mosquito species composition, abundance and seasonality were compared between irrigated and non-irrigated clusters. Anopheles mosquitoes were sorted out to species using morphological keys and molecular techniques. Chi square was used to test the relationships between Anopheles species occurrence, and environmental and seasonal parameters.ResultsOverall, 2108 female Anopheles mosquitoes comprising of six species were collected. Of these, 92.7% (n = 1954) were from irrigated clusters and 7.3% (n = 154) from the non-irrigated. The Anopheles gambiae complex was the most abundant (67.3%) followed by Anopheles coustani complex (25.3%) and Anopheles pharoensis (5.7%). PCR-based identification revealed that 74.7% (n = 168) of the An. gambiae complex were Anopheles arabiensis and 22.7% (n = 51) Anopheles amharicus. The density of An. gambiae complex (both indoor and outdoor) was higher in irrigated than non-irrigated clusters. The overall anopheline mosquito abundance during the wet seasons (87.2%; n = 1837) was higher than the dry seasons (12.8%; n = 271).ConclusionThe ongoing sugarcane irrigation activities in Arjo-Didessa created conditions suitable for malaria transmitting Anopheles species diversity and abundance. This could drive malaria transmission in Arjo-Didessa and its environs in both dry and wet seasons. Currently practiced malaria vector interventions need to be strengthened by including larval source management to reduce vector abundance in the irrigated areas.

Spatial heterogeneity and temporal dynamics of mosquito population density and community structure in Hainan Island, China

BackgroundMosquitoes are vectors of many tropical diseases. Understanding the ecology of local mosquito vectors, such as species composition, distributions, population dynamics, and species diversity is important for designing the optimal strategy to control the mosquito-borne diseases.MethodsEntomological surveillance of adult mosquitoes was conducted in five sites representing different ecological settings across Hainan Island from January to December of 2018 using BG Sentinel (BGS) traps and Centers for Disease Prevention and Control (CDC) light traps. In each site, we selected three areas representing urban, suburban and rural settings. Eighteen trap-days were sampled in each setting at each site, and CDC light traps and BGS traps were setup simultaneously. Mosquito species composition, distribution, population dynamics, and species diversity were analyzed. Mosquito densities were compared between different study sites and between different settings.ResultsNine species of mosquitoes belonging to four genera were identified. Culex quinquefasciatus (80.8%), Armigeres subalbatus (13.0%) and Anopheles sinensis (3.1%) were the top three species collected by CDC light traps; Cx. quinquefasciatus (91.9%), Ae. albopictus (5.1%), and Ar. subalbatus (2.8%) were the top three species collected by BGS traps. Predominant species varied among study sites. The population dynamics of Ae. albopictus, An. sinensis and Cx. quinquefasciatus showed clear seasonal variation regardless of study sites with a varied peak season for different species. Mosquito abundance of all species showed significant differences among different study sites and among urban, suburban and rural areas. Danzhou had the highest mosquito biodiversity, with an α, β, and Gini-Simpson biodiversity index of 8, 1.13 and 0.42, respectively. BGS traps captured Aedes mosquito at a higher efficiency than CDC light traps, whereas CDC light traps captured significantly more Anopheles and Armigeres mosquitoes than BGS traps.ConclusionsMosquitoes were abundant on Hainan Island with clear seasonality and spatial heterogeneity. Population density, species composition, distribution, and species diversity were strongly affected by the natural environment. Different tools are required for the surveillance of different mosquito species.

Breeding Habitat Distribution of Medically Important Mosquitoes in Kurunegala, Gampaha, Kegalle, and Kandy Districts of Sri Lanka and Potential Risk for Disease Transmission: A Cross-Sectional Study.

Some arbovirus infections, especially dengue, have increased rapidly over the last few decades in Sri Lanka. Prevalence and distribution of different mosquito species have been limitedly documented, which remains grossly inadequate in providing evidence for potential health risks. In this study, the diversity and species composition of mosquitoes in four selected districts in Sri Lanka (Kurunegala, Gampaha, Kegalle, and Kandy) were investigated. Entomological surveys were conducted from a total of 160 temporary and permanent mosquito breeding habitats identified in the study area from June 2017 to October 2018. Mosquito immature stages were sampled using standard dipping, siphoning, or pipetting methods and identified up to the species level. Percentage relative abundance and habitat characteristics such as species richness, dominance, and Shannon–Weiner diversity were calculated for each surveyed habitat type. Associations between co-occurring species were estimated by Hulbert's coefficient of interspecific association (C8). A total of 4663 mosquito larvae belonging to seven genera and fifteen species of mosquitoes were collected. The relative distribution of mosquito species differed significantly among the four studied districts (X2 = 143.248; df = 33; P < 0.001). According to Kruskal–Wallis statistics (P < 0.05 at 95% of significance), all diversity indices for immature stages of medically important mosquitoes varied significantly across different breeding sites. Paddy fields had the significantly highest species richness of 4.0 ± 2.82. The coefficients of interspecific association among all the recorded medically important vector mosquitoes were found negative during the present study. The findings of the current study would be useful to identify the entomological potential for disease transmission and facilitate the implementation of appropriate vector control interventions. This would ultimately provide an avenue to improve the personal skills of health staff rather than limiting their knowledge to specified disease vectors, under which the control program is concerned.

Residual Activity of Pyriproxyfen Against Mosquitoes in Catch Basins in Northwestern Riverside County, Southern California.

A field study was carried out on the year-long residual activity of the insect growth regulator (IGR) pyriproxyfen (Nylar 0.5G) in comparison with methoprene (Altosid® XRP Pellets) against mosquito developmental stages in catch basins in northwestern Riverside County, southern California. Pyriproxyfen was applied at 75, 100, 125, 150, 175 g per catch basin and methoprene at 3.5 g per catch basin. A total of 80 catch basins (10 per each treatment and 20 for control) were used. Posttreatment observations of catch basins were carried out at weekly intervals, with all pupal collections reared to adults. Mosquito species composition in this study, consisting mostly of Culex species (693), was predominated by Cx. quinquefasciatus (92.8%), followed by Cx. erythrothorax (5.5%), Cx. tarsalis (1.2%), Cx. stigmatosoma (0.3%), and Cx. thriambus (0.2%). Activity of both IGRs was expressed as percent inhibition of adult emergence (% IAE). Data generated on % IAE showed that, like methoprene, pyriproxyfen provided complete control of mosquitoes at 75, 125, and 175 g per catch basin up to 50 wk posttreatment at the Riverside amusement park, whereas its activity against mosquitoes in catch basins treated with 100 g and 150 g at the Eastvale site was short-lived, up to 48 wk. Water samples, bioassayed against laboratory-reared, 4th-stage larvae of Cx. quinquefasciatus 1-2 wk after the 50-wk-long study, showed evidence of significant % IAE (∼50) by pyriproxyfen at the 2 higher rates (125 g, 175 g) used at the amusement park. In conclusion, pyriproxyfen can be used to effectively control mosquitoes in catch basins for 48-50 wk, depending on the rate of application.

Anopheles Species Composition and Breeding Habitat Characterisation in Chiredzi District, Zimbabwe

Malaria is a public health concern in Zimbabwe and its transmission varies geographically and seasonally, corresponding with the country's rainfall pattern. Information on density and distribution of malaria vectors, species composition, breeding sites and quality assurance of the spray programme is limited for Chiredzi District. This study investigated mosquito species composition and distribution during winter, blood meal sources of adult collections, characteristics of aquatic larval habitats and quality of spraying as well as the insecticide residual activity on sprayed walls. Anopheline larvae were collected from breeding habitats that were subsequently characterised. Adult anophelines were sampled from both inside human dwellings and outdoors. Mosquitoes collected were identified morphologically and further processed to sibling species by polymerase chain reaction (PCR) where necessary. The enzyme-linked immunosorbent assay was used to detect Plasmodium falciparum circumsporozoite proteins and multiplex PCR was used to detect blood meal source. WHO cone bioassays were conducted to monitor spray quality and insecticide residual activity on spayed walls. A total of 21 aquatic habitats were identified from which anopheline larvae were sampled. Of these, 9 (42.9 %) were classified as permanent, 7 (33.3 %) as seasonal and 5 (23.8 %) as temporal. Anopheles mosquitoes from both adult and larval collections totalled to 153, with the former collection method accounting for 69.9 % (107) and the latter for 31.1 % (46). The collected mosquitoes were identified as An. quadriannulatus and An. funestus respectively. Out of the blood-fed An. funestus females, 70 % (n = 10) had fed on human blood. None of the adult collected mosquitoes tested positive for P. falciparum circumsporozoite proteins. The aquatic habitats surveyed indicated that breeding sites were mainly man-made. Anopheles funestus was the only malaria vector recorded during this study. This species is a particularly efficient vector and its detection is a cause for concern. Furthermore, 70 % of the adult-collected An. funestus female specimens had fed on humans confirming this species' strong tendency toward anthropophagy. A more comprehensive and year-round investigation is essential to gather appropriate and relevant entomological indices on malaria transmission in Chiredzi so as to enable effective vector control.

Malaria Vectors and Vector Surveillance in Limpopo Province (South Africa): 1927 to 2018.

Despite the annual implementation of a robust and extensive indoor residual spraying programme against malaria vectors in Limpopo Province (South Africa), significant transmission continues and is a serious impediment to South Africa’s malaria elimination objectives. In order to gain a better understanding regarding possible causes of this residual malaria, we conducted a literature review of the historical species composition and abundance of malaria vector mosquitoes in the Limpopo River Valley region of the Vhembe District, northern Limpopo Province, the region with the highest remaining annual malaria cases in South Africa. In addition, mosquito surveys were carried out in the same region between October 2017 and October 2018. A total of 2225 adult mosquitoes were collected using CO2-baited tent and light traps, human landing catches and cow-baited traps. Of the 1443 Anopheles collected, 516 were members of the An. gambiae complex and 511 An. funestus group. In the malaria endemic rural areas outside the Kruger National Park, one specimen each of An. gambiae s.s. and An. funestus and only three of An. arabiensis were collected. The latter species was abundant at a remote hot spring in the neighboring Kruger National Park. Eighteen other species of Anopheles were collected. Our survey results support the historical findings that An. arabiensis, the species widely held to be the prime malaria vector in South Africa, is a rare species in the malaria endemic Limpopo River Valley. The implications of the mosquito surveys for malaria transmission, elimination and vector control in northern Limpopo Province and neighboring regions are discussed.

Synopsis of the mosquitoes (Diptera: Culicidae) of Romania.

Mosquitoes (Diptera: Culicidae) are insects capable of transmitting various disease agents. They have a wide geographical range, with a higher diversity and distribution in the tropical and subtropical regions. In Romania, data on mosquito distribution are available mostly from the older literature and published in local journals; hence, it is inaccessible to the international scientific community. The aim of this review was to gather all the published data on mosquitoes in Romania by performing a comprehensive literature search, to create a publicly available georeferenced database for the distribution of mosquitoes and generate distribution maps to identify gaps in the knowledge of mosquito diversity and distribution in the country. The resultant database includes 1,509 unique records for 51 mosquito species representing seven genera: Aedes, Anopheles, Culex, Culiseta, Coquillettidia, Orthopodomyia and Uranotaenia. Knowledge of mosquito distributions is important for understanding the risks of mosquito-borne pathogens present in Romania, a country with high endemicity for various diseases, such as West Nile fever and dirofilariasis. The database also revealed important knowledge gaps, including the lack of data for the Carpathian Arch and the central part of the historical regions of Moldova and Oltenia. The gaps become more evident, as the presence and diversity of the vectors have not been studied in many areas where diseases caused by mosquito-borne pathogens are present. In conclusion, despite the numerous georeferenced records, large areas of Romania remain unexplored for the mosquito species composition, abundance and phenology. This review is a "call for action" for implementing active surveillance in the country.

Determination of Species Composition of Mosquitoes in Lahore, Pakistan.

Background:Present study was conducted to determine species composition of mosquitoes (larvae, pupae and adults) collected from ten different towns of Lahore from September 2014 to August 2015.Methods:Mosquito larvae, pupae and adults (male and female) were collected by using dippers and aspirators from September 2014 to August 2015 in different sites of Lahore comprising of ten towns i.e. Iqbal, Aziz Bhatti, Data Ganj Baksh, Gulberg, Nishtar, Ravi, Samanabad, Shalimar, Wagah, and Lahore Cantonment. Mosquito larvae and adults were identified by standard entomological keys. Diversity, richness and rarity of mosquito fauna were analyzed by the Shannon, Simpson and Margalef indices respectively.Results:In this study, a total of 8656 mosquitoes belonging to four genera namely Anopheles, Culex, Aedes and Mansonia were identified. Among fifteen species collected, Cx. quinquefasciatus was the most abundant species in the city having 25.8% relative abundance. However An. culicifacies s.l. (sensu lato) was reported as the least abundant species with 0.22% relative abundance. The highest diversity of mosquitoes was shown in the month of August (H= 2.25) while the lowest diversity was recorded June (H= 1.43). Extensive sewage water supported the maximum abundance of Cx. quinquifasciatus in urban areas of this city.Conclusions:This study has significantly elaborated the monthly varying species composition of mosquito fauna of this city. Hence this research will help us to find out the control strategies of mosquito borne diseases in this region.

Development of a low-cost imaging system for remote mosquito surveillance.

Targeted vector control strategies aiming to prevent mosquito borne disease are severely limited by the logistical burden of vector surveillance, the monitoring of an area to understand mosquito species composition, abundance and spatial distribution. We describe development of an imaging system within a mosquito trap to remotely identify caught mosquitoes, including selection of the image resolution requirement, a design to meet that specification, and evaluation of the system. The necessary trap image resolution was determined to be 16 lp/mm, or 31.25um. An optics system meeting these specifications was implemented in a BG-GAT mosquito trap. Its ability to provide images suitable for accurate specimen identification was evaluated by providing entomologists with images of individual specimens, taken either with a microscope or within the trap and asking them to provide a species identification, then comparing these results. No difference in identification accuracy between the microscope and the trap images was found; however, due to limitations of human species classification from a single image, the system is only able to provide accurate genus-level mosquito classification. Further integration of this system with machine learning computer vision algorithms has the potential to provide near-real time mosquito surveillance data at the species level.

Container Type Affects Mosquito (Diptera: Culicidae) Oviposition Choice.

Larvae of container-breeding mosquitoes develop in a wide range of container habitats found in residential neighborhoods. Different mosquito species may exhibit preference for different container types and sizes. Due to phenological differences, species composition in container habitats may change over time. We first conducted weekly neighborhood container surveys to determine the types of container habitats found in residential neighborhoods, and to determine mosquito species composition over time within these habitats. We then conducted an oviposition choice field assay to determine whether female mosquitoes of different species preferentially oviposit in different container types commonly found in neighborhoods. Halfway through the experiment, the largest container was removed at half the sites to test the hypothesis that incomplete source reduction alters oviposition preference among the remaining containers. In the neighborhood surveys, large containers had the greatest mosquito densities and the highest species richness. Aedes albopictus (Skuse), the most commonly collected mosquito, was found in all container types. The oviposition experiment indicated that Culex spp. females preferentially oviposit in large containers. When the largest container was removed, the total number of egg rafts decreased. Aedes spp. females preferred to oviposit in large- and medium-sized containers, but the total number of eggs laid did not change when the large container was removed. These results confirm that understanding habitat preferences of container-breeding mosquitoes is important to control efforts targeting vector species and that incomplete removal of container habitats may have unpredictable consequences for the distribution of juveniles among remaining habitats.

Mosquito Species Composition and Abundance in Quebec, Eastern Canada.

Given current and projected changes in the climate, the composition of mosquito species is predicted to shift geographically with implications for the transmission dynamics of vector-borne pathogens. Many mosquito species are rarely collected in Canada and their history is poorly understood; thus assessing their potential role as vectors for pathogenesis is difficult. Mosquitoes were collected from four trapping sites in Quebec Province, Canada, from June to September during 2018 and 2019 using BG sentinel traps. From all morphologically identified female mosquitoes, at least one specimen was selected for identification confirmation using the DNA-barcoding technique. Sequences were subjected to alignment and a Neighbor-Joining (NJ) tree was created using Geneious software. In total, 2,752 female mosquitoes belonging to 20 species over five genera: including Aedes (Ae.), Anopheles (An.), Culex (Cx.), Culiseta (Cu.), Coquillettidia (Cq.) were collected. The predominant mosquito was found to be Ae. cinereus. The highest number of mosquito species was captured in July, followed by August, September, and then June. Five genera were characterized by a distinctive set of cytochrome oxidase I (COI) sequences that formed well-supported clusters in the NJ-tree. The presence of Ae.japonicus in Quebec provides an initial look at the distribution of mosquito species in eastern Canada, which may put Canadians at risk of a wider range of arboviruses.

A survey of Anopheles species composition and insecticide resistance on the island of Bubaque, Bijagos Archipelago, Guinea-Bissau

BackgroundBubaque is the most populous island of the Bijagos archipelago, a group of malaria-endemic islands situated off the coast of Guinea-Bissau, West Africa. Malaria vector control on Bubaque relies almost exclusively on the use of long-lasting insecticidal nets (LLINs). However, there is little information on local vector bionomics and insecticide resistance.MethodsA survey of mosquito species composition was performed at the onset of the wet season (June/July) and the beginning of the dry season (November/December). Sampling was performed using indoor adult light-traps and larval dipping. Anopheles mosquitoes were identified to species level and assessed for kdr allele frequency by TaqMan PCR. Females were analysed for sporozoite positivity by CSP-ELISA. Resistance to permethrin and α-cypermethrin was measured using the CDC-bottle bioassay incorporating the synergist piperonyl-butoxide.ResultsSeveral Anopheles species were found on the island, all belonging to the Anopheles gambiae sensu lato (s.l.) complex, including An. gambiae sensu stricto, Anopheles coluzzii, Anopheles melas, and An. gambiae/An. coluzzii hybrids. Endophagic Anopheles species composition and abundance showed strong seasonal variation, with a majority of An. gambiae (50% of adults collected) caught in June/July, while An. melas was dominant in November/December (83.9% of adults collected). Anopheles gambiae had the highest sporozoite rate in both seasons, with infection rates of 13.9% and 20% in June/July and November/December, respectively. Moderate frequencies of the West African kdr allele were found in An. gambiae (36%), An. coluzzii (35%), An. gambiae/An. coluzzii hybrids (42%). Bioassays suggest moderate resistance to α-cypermethrin, but full susceptibility to permethrin.ConclusionsThe island of Bubaque maintained an An. gambiae s.l. population in both June/July and November/December. Anopheles gambiae was the primary vector at the onset of the wet season, while An. melas is likely to be responsible for most dry season transmission. There was moderate kdr allele frequency and synergist assays suggest likely metabolic resistance, which could reduce the efficacy of LLINs. Future control of malaria on the islands should consider the seasonal shift in mosquito species, and should employ continuous monitoring for insecticide resistance.

Anopheline Mosquito Species Composition, Kdr Mutation Frequency, and Parasite Infectivity Status in Northern Tanzania.

The scaling-up of malaria control interventions in northern Tanzania has resulted in a decline in malaria prevalence and vector species composition. Despite this achievement, residual malaria transmission remains a concern in the area. The main aim of this study was to investigate malaria vector species composition, parasite infectivity rates, and the presence of insecticide knockdown resistance (kdr) mutations in three sites that have experienced a significant decline in malaria in northern Tanzania. Adult mosquitoes were sampled using light traps in houses and hand-aspirators in cowsheds, whereas the standard dipping method was used for sampling mosquito larvae. Adult mosquitoes identified as Anopheles gambiae s.l. and An. funestus s.l. and larval stages III and IV of An. gambiae s.l. were stored in absolute ethanol for further laboratory molecular identification. The identified species in the An. gambiae complex were An. gambiae s.s., An. merus, An. quadriannulatus, and An. arabiensis, whereas the An. funestus group comprised An. funestus s.s., An. rivulorum, and An. leesoni. For An. gambiae s.s. analyzed from Zeneth, 47.6% were kdr-East homozygous susceptible, 35.7% kdr-East heterozygous resistant, 9.6% kdr-East homozygous resistant, and 7.1% undefined, whereas specimens from Kwakibuyu were 45.5% kdr-East homozygous susceptible, 32.7% kdr-East heterozygous resistant, 16.3% kdr-East homozygous resistant, and 5.5% undefined. There were no kdr-West alleles identified from any specimen. The overall malaria parasite infectivity rate was 0.75%. No infections were found in Moshi. The findings indicate that populations of the major malaria vector mosquitoes are still present in the study area, with An. funestus taking a lead in malaria transmission.

Species Composition of Mosquitoes from Boarding School Dormitories in Benin City, Edo State, Nigeria

This study investigated the distribution, species composition, and sex ratio of indoor resting mosquitoes alongside their relationship with climatic conditions in school dormitories located in Egor, Oredo and Ikpoba-okha Local Government Areas (LGAs) respectively in Benin City, Edo State, Nigeria. Indoor resting mosquitoes were collected with the aid of a sweep net and mechanical aspirator from randomly selected school dormitories between 08.00hr and 11.00hr from November (2011) to June (2012). The mosquitoes collected were identified using published morphological identification keys. A total of 766 mosquitoes containing four species: Culex quinquefasciatus (n=724; 94.5%), Anopheles gambiaes.l. (n=37; 4.8%), Culexannulioris (n=4; 0.5%) and Anopheles funestus (n=1; 0.1%) in descending order of importance, were collected. Cx.quinquefasciatus was the most predominant mosquito species in school dormitories across the three LGAs. Cx. annulioris and An. gambiaes.l were most abundant in school dormitories located in Oredo and Ikpoba-okha LGAs respectively. An.funestus occurred only in school dormitories located in Oredo LGA. Analysis of the relationship between meteorological data and species abundance varied significantly (P&lt;0.05) only among An. gambiaes.l with rainfall. There was significant difference (P&lt;0.05) in the sex ratio for all species obtained from the various locations except An. gambiae and Cx. annulioris in dormitories located in Oredo LGA Results of this study revealed the high presence of mosquito-borne disease risk within the school dormitories and environ, and therefore, the urgent need for properly planned, executed and regular evaluation of control measures.

Species Composition of Mosquitoes from Boarding School Dormitories in Benin City, Edo State, Nigeria

This study investigated the distribution, species composition, and sex ratio of indoor resting mosquitoes alongside their relationship with climatic conditions in school dormitories located in Egor, Oredo and Ikpoba-okha Local Government Areas (LGAs) respectively in Benin City, Edo State, Nigeria. Indoor resting mosquitoes were collected with the aid of a sweep net and mechanical aspirator from randomly selected school dormitories between 08.00hr and 11.00hr from November (2011) to June (2012). The mosquitoes collected were identified using published morphological identification keys. A total of 766 mosquitoes containing four species: Culex quinquefasciatus (n=724; 94.5%), Anopheles gambiaes.l. (n=37; 4.8%), Culexannulioris (n=4; 0.5%) and Anopheles funestus (n=1; 0.1%) in descending order of importance, were collected. Cx.quinquefasciatus was the most predominant mosquito species in school dormitories across the three LGAs. Cx. annulioris and An. gambiaes.l were most abundant in school dormitories located in Oredo and Ikpoba-okha LGAs respectively. An.funestus occurred only in school dormitories located in Oredo LGA. Analysis of the relationship between meteorological data and species abundance varied significantly (P&lt;0.05) only among An. gambiaes.l with rainfall. There was significant difference (P&lt;0.05) in the sex ratio for all species obtained from the various locations except An. gambiae and Cx. annulioris in dormitories located in Oredo LGA Results of this study revealed the high presence of mosquito-borne disease risk within the school dormitories and environ, and therefore, the urgent need for properly planned, executed and regular evaluation of control measures.