Characteristics Of Larval Habitats Research Articles

Species diversity of mosquitoes (Diptera: Culicidae), larval habitat characteristics, and potential as vectors for lymphatic filariasis in Central Bengkulu Regency, Indonesia

Species diversity of mosquitoes (Diptera: Culicidae), larval habitat characteristics, and potential as vectors for lymphatic filariasis in Central Bengkulu Regency, Indonesia

Investigation of the Diversity of Fauna and Larval Habitat Characteristics of Culex Mosquitoes, the Potential Arboviruses Vectors in South East of Iran

Introduction: Arboviruses have been a persistent public health challenge in Iran for the past 50 years. Culex mosquitoes are the main vectors of these viruses. Different aspects of these vectors, including their phenotypic characteristics, insecticide resistance, and the potential for infection transmission, were regularly reported from different parts of the world. The present study aimed to determine the fauna and prevalence of the Culex larval stage in four sites in Kerman province, Iran from March to September 2019. Method: In total, 450 samples of Culex mosquito larvae were collected and identified using valid taxonomic keys. Physical and biological characteristics data of the larval habitats, including water situation, sunlight situation, and habitat kind, were recorded. Results: Two Culex species, Culiseta longiareolata and Culex quinquefasciatus, were detected with prevalence rates of 88.8% and 11.2%, respectively. The recorded temperatures in larval habitats ranged from 16 to 28 ◦C. Kerman City, Iran exhibited the highest prevalence of detected Culex mosquito larvae among the studied areas. Moreover, Rayen City and Sirjan City in Iran had the lowest and highest temperature rates, respectively. The temporary habitats were the most prevalent sites for larvae collection. Conclusion: This study provided a snapshot of the predominant Culex mosquito fauna in Kerman, serving as a foundation for future molecular studies, identification of insecticide-resistant fauna, and exploration of the potential for initial transmission and continuation of zoonotic infections.

Physicochemical characteristics of larval habitats and biodiversity of mosquitoes in one of the most important metropolises of southern Iran

The present study aimed to investigate the roles of the physicochemical characteristics of larval habitats in biodiversity and other bionomic factors of mosquitoes in Shiraz.The physical parameters of all habitats were recorded separately. The collected mosquito larvae were identified based on morphological characters. The water samples of larval habitats were analyzed for Biochemical Oxygen Demand (BOD, mg/L), Chemical Oxygen Demand (COD, mg/L), pH, alkalinity, turbidity, total hardness (mg/L), Electrical Conductivity (EC, μS/cm), Total Dissolved Solids (TDS, mg/L), Cl2 (mg/L), and water temperature (°C). In addition, three main indices were used for surveying biodiversity.A total of 1229 larvae were collected from April to September 2018 and May to August 2019. Seven medically important mosquito species were identified morphologically. Culex quinquefasciatus and Cx. laticinctus had the highest distribution and abundance. Ecological results showed that the richness and diversity of species were higher and more stable in natural sites than in manmade places. The optimum BOD, COD, alkalinity, TDS, EC, pH, and temperature of water for mosquitoes of the studied areas were 140 mg/L, 360 mg/L, 160 mg/L, 420 mg/L, 840 μS/cm, 8.3, and 24 °C, respectively. Most mosquitoes tended to live in manmade, temporary, and sunny larval habitats with turbid water.The results provided a better understanding of the biology and ecology of mosquitoes as the most important group of disease vectors to humans and animals. Hence, they could be used to apply some safer and more environmentally friendly methods for mosquito control.

The Abundance of Mosquito Larval Species (Diptera: Culicidae) and the Physicocemical Characteristics of Their Habitat in Rice Field at Dramaga Sub-District, Bogor Regency

This study aims to identify the species diversity, density, and their distribution and analyze mosquito larvae' habitat's physicochemical characteristics in the Dramaga sub-district, Bogor Regency rice fields.. This research used purposive sampling method by taking samples from 92 breeding site in four villages of Dramaga district. The physicochemical characteristics of larval habitats, including pH, temperature, Total Dissolve Solid (TDS), and Electrical Conductivity (EC) were measured in the field. Breeding site are marked using a Garmin Montana 680 GPS for further processing. Larvae were collected and identified until species level. The result showed Anopheles vagus, An. barbirostris, An. indefinitus, Culex. vishnui, Cx. fuscocephala, Cx. tritaeniorhynchus, Cx. sitiens, Cx. hutchinsoni, and Armigeres sp. were found in the rice fields of Dramaga district. The highest diversity and density of larvae was found in Cikarawang Village. The highest relative abundance of mosquitoes larvae were An. vagus and Cx. vishnui. The physicochemical characteristics of larval habitats such as pH, TDS, and EC, had no correlation with the larval abundance, however the temperature of larval habitat had a negative correlation between temperature and larval density.

The Abundance of Mosquito Larval Species (Diptera: Culicidae) and the Physicocemical Characteristics of Their Habitat in Rice Field at Dramaga Sub-District, Bogor Regency

This study aims to identify the species diversity, density, and their distribution and analyze mosquito larvae' habitat's physicochemical characteristics in the Dramaga sub-district, Bogor Regency rice fields.. This research used purposive sampling method by taking samples from 92 breeding site in four villages of Dramaga district. The physicochemical characteristics of larval habitats, including pH, temperature, Total Dissolve Solid (TDS), and Electrical Conductivity (EC) were measured in the field. Breeding site are marked using a Garmin Montana 680 GPS for further processing. Larvae were collected and identified until species level. The result showed Anopheles vagus, An. barbirostris, An. indefinitus, Culex. vishnui, Cx. fuscocephala, Cx. tritaeniorhynchus, Cx. sitiens, Cx. hutchinsoni, and Armigeres sp. were found in the rice fields of Dramaga district. The highest diversity and density of larvae was found in Cikarawang Village. The highest relative abundance of mosquitoes larvae were An. vagus and Cx. vishnui. The physicochemical characteristics of larval habitats such as pH, TDS, and EC, had no correlation with the larval abundance, however the temperature of larval habitat had a negative correlation between temperature and larval density.

Diversity and larval habitats of mosquitoes (Diptera: Culicidae) in urban areas in Ha Noi, Vietnam

Although some mosquito-borne diseases have been thriving in Ha Noi city, Vietnam very few studies on mosquitoes have been conducted. Determining how the species composition and abundance of mosquito vectors depend on environmental resources in different habitats addresses where different types of vector control need to be applied. The present study aims to investigate the characteristics of larval habitats and to provide a composition of mosquitoes (Culicidae) in this city. Surveys of larval and adult mosquitoes were carried out from different habitats in urban areas during rainy seasons from 2018 to 2023. Overall, in almost all water containers that were surveyed (80.9%), immature mosquitoes were present. A total of 4593 mosquitoes including 3,950 larvae and 643 adults were collected from 16 sampling sites. Twelve mosquito species belonging to 6 genera were collected and identified. Aedes albopictus and Culex quinquefasciatus were the most common and abundant species, each accounting for 34% of the total collected larval specimens. Five species, Anopheles umbrosus, Culex cintellus, Armigeres subalbatus, Mansonia annulifera, and Lutzia fuscana were the first records for Ha Noi city. The species composition varied between different habitat types. Peri-domestic habitats were the most common breeding sites for mosquitoes in the study area. Noteworthy, species belonging to genus Aedes were abundant in domestic habitats created by anthropogenic materials while that of genus Culex was mainly thriving in large water bodies in both peri-domestic and natural habitats. The current results show a variation in the distribution and abundance of mosquitoes in urban areas of Ha Noi which should be considered for effective planning and implementing mosquito control programs in the city.

Larval habitat stability and productivity in two sites in Southern Ghana

BackgroundMosquito larval source management (LSM) is a valuable additional tool for malaria vector control. Understanding the characteristics of mosquito larval habitats and its ecology in different land use types can give valuable insight for an effective larval control strategy. This study determined the stability and productivity of potential anopheline larval habitats in two different ecological sites: Anyakpor and Dodowa in southern Ghana.MethodsA total of 59 aquatic habitats positive for anopheline larvae were identified, and sampled every two weeks for a period of 30 weeks using a standard dipping method. Larvae were collected using standard dippers and were raised in the insectary for identification. Sibling species of the Anopheles gambiae sensu lato (s.l.) were further identified by polymerase chain reaction. The presence of larval habitats, their stability and larvae positive habitats were compared between the two sites using Mann–Whitney U and the Kruskal–Wallis test. Factors affecting the presence of An. gambiae larvae and physicochemical properties at the sites were determined using multiple logistic regression analysis and Spearman’s correlation.ResultsOut of a total of 13,681 mosquito immatures collected, 22.6% (3095) were anophelines and 77.38% (10,586) were culicines. Out of the 3095 anophelines collected, An. gambiae s.l. was predominant (99.48%, n = 3079), followed by Anopheles rufipes (0.45%, n = 14), and Anopheles pharoensis (0.064%, n = 2). Sibling species of the An. gambiae consisted of Anopheles coluzzii (71%), followed by An. gambiae s.s. (23%), and Anopheles melas (6%). Anopheles mean larval density was highest in wells [6.44 (95% CI 5.0–8.31) larvae/dip], lowest in furrows [4.18 (95% CI 2.75–6.36) larvae/dip] and man-made ponds [1.20 (95% CI 0.671–2.131) larvae/dip].The results also revealed habitat stability was highly dependent on rainfall intensity, and Anopheles larval densities were also dependent on elevated levels of pH, conductivity and TDS.ConclusionThe presence of larvae in the habitats was dependent on rainfall intensity and proximity to human settlements. To optimize the vector control measures of malaria interventions in southern Ghana, larval control should be focused on larval habitats that are fed by underground water, as these are more productive habitats.Graphical

Investigation on Mosquitoes Fauna (Diptera: Culicidae) and Probable Vector of West Nile Virus in Lorestan Province, Western Iran.

Fauna and larval habitat characteristics studies on mosquitoes are important tools to identify the breeding places of the vectors and management of the control strategies. This study was done to provide data on Culicidae fauna, larval habitat characteristics and identifying potential vectors of West Nile virus in Lorestan Province, west of Iran. Culicidae mosquitoes were collected at three counties and nine site stations from Lorestan Province, west of Iran in 2017. Adult mosquitoes were collected using human and animal bite collection methods, New Jersey and CDC light traps and pit shelters by aspirator. Larva were collected by dipping method. RT-PCR technique was employed for detection of the West Nile virus among mosquito's samples. 4805 mosquitoes were collected from three counties and nine sites in Lorestan Province during June-October 2017, including 4363 adults and 442 larvae. The most abundant species collected from all counties in both adult and larval stages were Culex pipiens (49.10%), Cx. theileri (31.82%), Anopheles maculipennis (11.09%), An. superpictus (2.66%), An. stephensi (2.12%), Cx. perexiguus (1.89%), An. dthali (1.17%) and An. sacharovi (0.15%) respectively. West Nile virus was detected in none of mosquitoes examined. The results of this study revealed that arbovirus vectors such as Cx. pipiens along with Cx. theileri and Cx. perexiguus are well adapted to a broad range of habitats and different climatic conditions in Lorestan Province. That necessitates further routine surveillance of arboviral infections.

The Fauna, Diversity, and Bionomics of Culicinae (Diptera: Culicidae) in Hormozgan Province, Southern Iran.

Hormozgan Province is one of the important foci of malaria in Iran. In addition to malaria pathogens, mosquitoes also transmit the pathogens that cause dirofilariasis and West Nile fever in the province. Also, the threat of emerging aedine-borne viruses that cause infections, such as Chikungunya, dengue, and Zika, is noticeable. There is little information about the fauna and bionomics of Culicinae in the province. The present investigation aimed to study the fauna, diversity, and bionomics of culicines. The study was conducted from September 2016 to April 2017 in four counties of Bandar Abbas, Bandar Khamir, Bashagard, and Jask. In total, 3,236 larvae and 1,901 adults including 16 culicine species were collected. The larvae of Culiseta longiareolata (Macquart) (25.65%), Culex pipiens Linnaeus (16.62%), and Cx. quinquefasciatus Say (16.16%) were most abundant and Cx. hortensis Ficalbi (0.09%) was least abundant. Among adults, Cx. laticinctus Edwards (33.19%), Cx. quinquefasciatus (31.09%), and Cx. pipiens (11.99%) were the most prevalent species and Cs. longiareolata (0.47%), Aedes caballus (Theobald) (0.90%), and Cx. bitaeniorhynchus Giles (0.90%) were the least prevalent species. The pairwise similarities of fauna of the counties and different collecting methods and diversity indices were investigated. More ecological data, especially on host preference, seasonality, and larval habitat characteristics, are needed as a basic knowledge for any intervention measures using integrated vector management.

Larval habitats characteristics of Culicinae subfamily in the south of Iran

Abstract. Doosti S, Yaghoobi-Ershadi MR, Sedahhat MM, Akbarzadeh K, Godwin GN. 2021. Larval habitats characteristics of Culicinae subfamily in southern of Iran. Nusantara Bioscience 13: 194-201. Globally, mosquitoes (Diptera: Culicidae) are known vectors of many diseases such as Malaria, Dengue fever, Sindbis, West Nile virus, Rift Vally fever, Japanese encephalitis, and Filariasis. This study aimed to determine larval habitat characteristics of mosquitoes in the southern part of Iran during 2009-2013. The study was carried out in mosquitoes' larval habitats, and samples were collected using dipping and pipette methods. The larvae were kept in lactophenol solution and transferred to the laboratory of Medical Entomology. Then, microscopic slides were prepared and species were identified using reliable morphological keys. Characteristics of larval breeding places were investigated based on the habitat type, water conditions, vegetation, and sunlight exposure. A total of 8188 mosquito larvae were collected from 209 different breeding places. In all, 20 mosquito species belonging to 4 genera were identified. Culex quienquefaciatus, Cx. pipiens, Culiseta longiareolata, Cx. tritaeniorhynchus, Cx. sitiens, Cx. theileri and Aedes caspius were the most common species found in this study. The southern part of Iran has the most wharfs and airports across the country. Additionally, there is a high diversity of medically important mosquito species like Cx. pipiens and Cx. tritaeniorhynchus, Ae. albopictus and Ae. vexans from the Culicidae family. The species are capable of vectoring various diseases in the southern part of Iran; hence, there is a need for more investigations.

Fauna and Larval Habitat Characteristics of Mosquitoes (Diptera: Culicidae) in Kashan County, Central Iran, 2019.

Background:Mosquitoes are responsible for spreading devastating parasites and pathogens causing some important infectious diseases. The present study was done to better understand and update the fauna of Culicidae and to find out the distribution and the type of their larval habitats in Kashan County.Methods:This study was done in four districts of Kashan County (Central, Qamasr, Niasar and Barzok). Mosquito larvae were collected from 23 active larval habitats using a standard 350ml capacity mosquito dipper from April to late December 2019. The collected larvae were transferred to containers containing lactophenol, and after two weeks individually mounted in Berlese's fluid on a microscope slide and identified to species by morphological characters and valid keys.Results:In this study, a total of 9789 larvae were collected from urban and rural areas in Kashan County. The identified genera were Anopheles, Culiseta and Culex. In this study larvae of An. turkhudi, Cx. perexiguus, Cx. mimeticus, Cx. deserticola and Cs. subochrea were collected for the first time from Kashan County.Conclusion:The results of this study indicate the presence and activity of different mosquito species in Kashan County that some of them are vectors of arbovirus and other vector-borne diseases.

The application of drones for mosquito larval habitat identification in rural environments: a practical approach for malaria control?

BackgroundSpatio-temporal trends in mosquito-borne diseases are driven by the locations and seasonality of larval habitat. One method of disease control is to decrease the mosquito population by modifying larval habitat, known as larval source management (LSM). In malaria control, LSM is currently considered impractical in rural areas due to perceived difficulties in identifying target areas. High resolution drone mapping is being considered as a practical solution to address this barrier. In this paper, the authors’ experiences of drone-led larval habitat identification in Malawi were used to assess the feasibility of this approach.MethodsDrone mapping and larval surveys were conducted in Kasungu district, Malawi between 2018 and 2020. Water bodies and aquatic vegetation were identified in the imagery using manual methods and geographical object-based image analysis (GeoOBIA) and the performances of the classifications were compared. Further, observations were documented on the practical aspects of capturing drone imagery for informing malaria control including cost, time, computing, and skills requirements. Larval sampling sites were characterized by biotic factors visible in drone imagery and generalized linear mixed models were used to determine their association with larval presence.ResultsImagery covering an area of 8.9 km2 across eight sites was captured. Larval habitat characteristics were successfully identified using GeoOBIA on images captured by a standard camera (median accuracy = 98%) with no notable improvement observed after incorporating data from a near-infrared sensor. This approach however required greater processing time and technical skills compared to manual identification. Larval samples captured from 326 sites confirmed that drone-captured characteristics, including aquatic vegetation presence and type, were significantly associated with larval presence.ConclusionsThis study demonstrates the potential for drone-acquired imagery to support mosquito larval habitat identification in rural, malaria-endemic areas, although technical challenges were identified which may hinder the scale up of this approach. Potential solutions have however been identified, including strengthening linkages with the flourishing drone industry in countries such as Malawi. Further consultations are therefore needed between experts in the fields of drones, image analysis and vector control are needed to develop more detailed guidance on how this technology can be most effectively exploited in malaria control.

Downstream Changes in Odonate (Insecta: Odonata) Communities along a Suburban to Urban Gradient: Untangling Natural and Anthropogenic Effects.

Simple SummaryDragonflies are sensitive to natural and human-caused variation in the aquatic and terrestrial habitats where their larvae and adults live. For example, a reduction in shady vegetation, as a consequence of increasing stream size or streamside deforestation, often causes a reduction in specialized forest species and an increase in generalist species. We surveyed larvae and adults at 15 sites along the Reedy River in Greenville Co, SC, USA, from headwater sites in forested suburban landscapes through the urban core of the city of Greenville. We described the sediment characteristics and shoreline vegetation in two 4 m × 20 m plots at each site, and measured the percentage of developed land, forested land, grasslands, and wetlands within 500 m of each plot center. At a small scale, within plots, larval abundance and diversity increased with increasing amounts of dead debris that may provide a refuge from predators. Adult abundance and diversity correlated with the amount of aquatic and shoreline vegetation used as perches. At a large scale, diversity responded more to natural changes in habitat than urbanization: damselfly diversity increased downstream and dragonfly diversity was greatest in sunny, open habitats with fields, wetlands, and open water.The community structure of lotic odonates (Insecta: Odonata) changes downstream, but it is difficult to untangle natural and anthropogenic causes. We surveyed larvae and adults at 15 sites along the Reedy River in Greenville Co., SC, USA, from sites in forested suburban landscapes through the urban core of the city of Greenville. We used principal component analyses and Akaike information criteria models to describe the relationships between larval and adult community descriptors (abundance, richness, and diversity) and habitat characteristics at several spatial scales, including water chemistry, sediment and detritus, aquatic and streamside vegetation, and the percent cover of landforms in the surrounding landscape. At all scales, larval abundance, richness, and diversity correlated with the amount of detritus. At a small scale, adult indices correlated with the amount of sunlight and streamside vegetation. Zygopteran community composition was nested at a large scale; richness and diversity did not correlate with changes in the landscape but increased downstream. Anisopteran composition was also nested, but richness correlated with the percent cover of field, wetland, and open water in the habitat and was unrelated to downstream site position. Landscape transformation affected anisopterans more than zygopterans by opening habitats that facilitate these generalist heliotherms.

Aedes albopictus Populations and Larval Habitat Characteristics across the Landscape: Significant Differences Exist between Urban and Rural Land Use Types.

Simple SummaryMore than 50% of the global population now resides in cities. In addition to large human populations, some cities support large populations of vectors, such as mosquitoes. Consequently, we have seen a resurgence in urban outbreaks of mosquito borne diseases, e.g., West Nile and dengue fever, in the last 60 years. The Asian Tiger mosquito, Aedes albopictus, is an ecologically flexible species that has colonized every continent, except Antarctica, in recent decades. In this paper, we tested the prediction that A. albopictus is more abundant in human-dominated, urban, and suburban areas compared to rural areas in a temperate US city. We collected data on mosquito abundance and other aspects of the environment important for mosquitoes and that also may vary by land use type. As predicted, we found higher densities of A. albopictus in urban and suburban areas compared to rural ones. We also found few other mosquito species, higher average temperatures, lower nitrogen levels in aquatic larval habitats, and faster water evaporation in some sample weeks. We conclude that this species is thriving in human-dominated areas in this metropolitan region, and its success may be partially due to the environmental characteristic of this habitat type.One of the most profound recent global changes has been the proliferation of urban metropolitan areas. A consequence of urbanization is a reduction in abundance, or diversity, of wildlife. One exception, is the proliferation of vectors of disease; recent years have seen the emergence and resurgence of diseases vectored by species closely associated with humans. Aedes albopictus, a mosquito with a near global range and broad ecological niche, has been described as an urban, suburban, or rural vector, or a forest edge species depending on local conditions. We tested the hypothesis that abundance and phenological patterns of this species vary among different land use types in a temperate city because of the variation in the biotic and abiotic conditions characteristic of those habitat types. A. albopictus populations in urban and suburban areas were an order of magnitude larger than in rural areas and were detected several weeks earlier in the season. Additionally, we found fewer overall mosquito species, higher temperatures, lower nitrogen, higher pH, and faster water evaporation in larval habitats in urban vs. rural areas. By understanding the ecological differences that facilitate a species in one habitat and not another, we can potentially exploit those differences for targeted control.

Larval habitats and species diversity of mosquitoes (Diptera: Culicidae) in West Azerbaijan Province, Northwestern Iran

BackgroundThe characteristics of a larval habitat is an important factor which affects the breeding pattern and population growth of mosquitoes Information about the larval habitat characteristics and pupal productivity can be utilized for the surveillance of the level of population growth, species diversity, and preferred breeding sites of mosquitoes, which are important aspects of integrated vector control. In the present study, mosquito larvae were collected from 22 natural habitats in five counties of the West Azerbaijan Province in the Northwest of Iran during May–November 2018. Physicochemical characteristics of the habitats were investigated. These included alkalinity, chloride (Cl) content, water temperature (°C), turbidity (NTU), Total Dissolved Solids (TDS) (ppm), Electrical Conductivity (EC) (μS/cm), and acidity (pH). The index of affinity between the collected species was calculated using Fager & McGowan test.ResultsA total of 2715 specimens were collected and identified. Seven different species belonging to four genera were identified in our study sites. The species included, Culex pipiens Linnaeus 1758, Culex theileri Theobald 1903, Culex mimeticus Noé 1899, Culex modestus Ficalbi 1947, Culiseta longiareolata Macquart 1838, Anopheles maculipennis Meigen 1818complex, and Aedes caspius Pallas 1771. There was a significant difference in chloride content and water temperature preferences among the different species (P < 0.05). Also, there was no significant difference in pH, Alkalinity, Turbidity, TDS, and EC preferences among the different species (P > 0.05). The affinity between the pair of species Cx. mimeticus/Cs. longiareolata was 0.526. There was no affinity between other pairs of species or the affinity was very weak.ConclusionsThe physicochemical and biological characteristics of mosquito larval habitats play an important role in zoning of areas suitable for breeding and distribution. Surveillance of these characteristics can provide valuable information for entomological monitoring of mosquito vectors and for designing targeted control programs. Also, further studies should be undertaken in a wider geographical area, taking into account the complex characteristics of the physicochemical and ecological factors of the study area and their interaction with various mosquito species.

Seasonal abundance and larval habitats characterization of mosquito species in Lagos State, Nigeria

The knowledge of the ecology and abundance of mosquito is important in determining the potential risk of exposure to mosquito-borne diseases and the appropriate control measure to effectively reduce the mosquito population. A survey was carried out in four Local Government Areas (LGAs) of Lagos State, Nigeria for one year to determine the abundance, diversity, and larval habitat characteristics of mosquito. Larvae were collected using WHO standard methods, the physiochemical characteristics of the habitats were recorded, the larvae were reared to adults and identified using morphological identification keys and molecular assays. Adult mosquitoes were also collected outdoor using a trap with octanol attractant. Five species belonging to 3 genera were collected and identified as Anopheles gambiae complex, Anopheles funestus complex, Culex quinquefasciatus, Aedes aegypti, and Aedes albopictus. Cx quinquefasciatus (37.7%) is the most abundant followed by Ae aegypti (31.3%) and An. gambiae s.l. (26.9%) while Ae. albopictus (1.9%) is the least abundant. The larval abundance within the different species showed a high level of statistical significance (P<0.001). Simpson's index was found to range from 0.6751 to 0.6926 for all the sampled locations while the Shannon index ranges from 1.187 to 1.242 and Evenness ranges from 0.6566 to 0.7134. The average physiochemical parameter of the water bodies harboring the mosquito larvae includes pH ranging from 7.2 ± 0.1 to 7.7 ± 0.2, Conductivity ranging from 0.35±0.2 to 0.83±0.46, temperature ranging from 28.7 ± 0.65 to 31.3 ± 0.71, and TDS ranging from 330±158.4 to 571.5 ± 320. An increase in the global temperature as a result of climate change could have an effect on temperature and other physiochemical parameters of mosquito larval habitats, thereby altering the duration of their metamorphosis, subsequently an upsurge in adult mosquito abundance leading potential outbreak of mosquito-borne diseases.

Vertical Distribution, Biodiversity, and Some Selective Aspects of the Physicochemical Characteristics of the Larval Habitats of Mosquitoes (Diptera: Culicidae) in Chaharmahal and Bakhtiari Province, Iran

Background and aims: Mosquitoes (Diptera: Culicidae) are still a focus of research because of their role in the transmission of diseases and annoying biting behavior. Source reduction is an effective measure to control mosquito populations, which is based on good knowledge of larval habitats. This study was conducted to obtain that basic knowledge in Chaharmahal and Bakhtiari province. Methods: This study was carried out in 2011 and 2012. Geographical coordinates, altitude, pH, temperature, and the dissolved oxygen level of larval habitats were recorded by relevant devices, followed by documenting physical attributes by direct observation. In addition, the indices of biodiversity were calculated to analyze the vertical biodiversity of species. Finally, the affinity index was calculated to elucidate species co-occurrence. Results: Eighteen species were recovered from 92 larval habitats. Low- (≤ 1400 m), mid- (1401–2000 m), and high- (≥ 2001 m) altitudes lodged 7, 17, and 14 species, respectively. Further, the indices of the species richness and biodiversity for these altitudinal categories were 0.93, 1.94, and 1.58, as well as 1.54, 2.13, and 1.96, respectively. Larval habitats were mostly natural, temporary, with standing but clear water, muddy substrate, sunlit, and with vegetation. Other physicochemical characteristics and affinity of species were described and discussed as well. Conclusion: To the best of our knowledge, this is the first report of vertical distribution and biodiversity of mosquito larvae in Iran. The relative uniformity of physicochemical characteristics of larval habitats was attributed to prevailing water resources in the studied area and sampling design. The oviposition site selection of gravid mosquitoes is still an unresolved problem which needs further investigations.

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.

Larval habitat characteristics and predicting the distribution of Culex tritaeniorhynchus using maximum entropy (MaxEnt) modelin Golestan Province (north of Iran).

Culex tritaeniorhynchus is a widely distributed and medically important mosquito species (Diptera: Culicidae). The aim of this study was to determine characteristics of larval habitats and predict the distribution of Cx. Tritaeniorhynchus using maximum entropy (MaxEnt) model in Golestan Province (north of Iran). Overall, 53 villages and cities from the 14 counties in the Golestan Province were studied. Suitable habitats for sampling of mosquitoes were determined in the selected villages. Larval sampling was carried out 10 times using a standardized dipper (350 ml). Captured larvae in each dipper were counted and kept in special containers. Larvae were put in lactophenol and were then mounted on microscope slides prepared according to the de Faure's formula. All villages where Cx. tritaeniorhynchus was isolated from were considered as the species presence points, and their coordinates were extracted from the GIS. The obtained data were entered into the model in Microsoft Excel 2003. Layers required for the study were obtained from the World Clim global climate database at a spatial resolution of 1 km2. The MaxEnt software (version 3.3.3) was used to predict the most suitable ecological niches of Cx. tritaeniorhynchus. Out of the 5168 specimens collected from 53 villages and cities, 1097 specimens (21%) were identified as Cx. tritaeniorhynchus. The central and western areas of the province are environmental suitability areas for distribution of this species compared to the other areas. Area under curve (AUC) value for Cx. tritaeniorhynchus was 0.888. Environmental variables with highest gain in the model were precipitation of coldest quarter (bio19), maximum temperature of warmest month (bio5) and slope. Precipitation and temperature are important determinants of Cx. tritaeniorhynchus distribution in Golestan Province.

Habitat associations of Culicoides species (Diptera: Ceratopogonidae) abundant on a commercial cervid farm in Florida, USA

BackgroundBiting midges in the genus Culicoides (Diptera: Ceratopogonidae) transmit bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) to ruminants, thus exerting a significant economic impact on animal agriculture worldwide. However, very little is known about the larval habitat characteristics of Culicoides species associated with BTV/EHDV transmission, particularly in southeastern USA, limiting the establishment of effective midge control strategies. In this study, we examined the habitat associations of Culicoides species abundant on a commercial cervid farm in Florida, USA and quantified several environmental variables of their habitat to identify the key variables associated with midge abundance.MethodsMud/substrate samples from three potential larval habitats on the farm (edges of streams, puddles and seepages) were brought to the laboratory and incubated for adult emergence, and the percentage organic matter, macronutrients, micronutrients, pH, electrical conductivity, moisture and microbial concentrations of the substrate were quantified.ResultsStrong habitat associations were observed for Culicoides haematopotus (Malloch) (stream edge), Culicoides stellifer (Coquillett) (puddles) and Culicoides loisae (Jamnback) (stream edge), the most commonly emerging midge species from the samples. Suspected vector species of BTV/EHDV on the property, C. stellifer and Culicoides venustus (Hoffman), emerged mainly from habitats with moderate-high levels of pollution (edges of puddles and seepages) as indicated by the relatively higher concentrations/levels of organic matter, nutrients and other environmental variables in these samples. The emergence of C. insignis was too low to form any meaningful conclusions. For each Culicoides species, only weak positive or negative associations were detected between midge abundance and the various environmental variables quantified.ConclusionsHabitat associations of Culicoides species abundant on a local cervid/animal farm vary, most likely as a function of certain biotic/abiotic characteristics of the habitat. Further studies across a larger spatial and temporal scale will be needed to experimentally evaluate/identify the key factors more strongly associated with the abundance of target Culicoides species. This information, in the long term, can be potentially exploited to render local habitats unsuitable for midge oviposition/larval development.