Larval habitat diversity and mosquito species distribution along the coast of Kenya

Background: Management of arboviruses relies heavily on vector control. Implementation and sustenance of effective control measures requires regular surveillance of mosquito occurrences, species abundance and distribution. The current study evaluated larval habitat diversity and productivity, mosquito species diversity and distribution in selected sites along the coast of Kenya. Methods: A cross-sectional survey of mosquito breeding habitats, species diversity and distribution was conducted in urban, peri-urban and forested ecological zones in Mombasa and Kilifi counties. Results: A total of 13,009 immature mosquitoes were collected from 17 diverse aquatic habitats along the coast of Kenya. Larval productivity differed significantly (F (16, 243) = 3.21, P < 0.0001) among the aquatic habitats, with tyre habitats recording the highest larval population. Culex pipiens (50.17%) and Aedes aegypti (38.73%) were the dominant mosquito species in urban areas, while Ae. vittatus (89%) was the dominant species in forested areas. In total, 4,735 adult mosquitoes belonging to 19 species were collected in Haller Park, Bamburi, Gede and Arabuko Sokoke forest. Urban areas supported higher densities of Ae. aegypti compared to peri-urban and forest areas, which, on the other hand, supported greater mosquito species diversity. Conclusions: High Ae. aegypti production in urban and peri-urban areas present a greater risk of arbovirus outbreaks. Targeting productive habitats of Aedes aegypti, such as discarded tyres, containers and poorly maintained drainage systems in urban areas and preventing human-vector contact in peri-urban and forested areas could have a significant impact on the prevalence of arboviruses along the coast of Kenya, forestalling the periodic outbreaks experienced in the region.

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Habitat characterization and insecticide susceptibility profiles of Aedes aegypti mosquitoes in Ifakara area, south-eastern Tanzania

10.21203/rs.2.18588/v1 ◽

2019 ◽

Author(s):

Najat F. Kahamba ◽

Alex J. Limwagu ◽

Salum A. Mapua ◽

Betwel J. Msugupakulya ◽

Dickson S. Msaky ◽

...

Keyword(s):

Aedes Aegypti ◽

Urban Areas ◽

Significant Risk ◽

Pathogen Transmission ◽

Effective Control ◽

Aquatic Habitats ◽

Insecticide Susceptibility ◽

South Eastern ◽

Tree Holes ◽

Dry And Rainy Seasons

Abstract Background: Aedes-borne diseases such as dengue and chikungunya constitute constant threats globally. In Tanzania, these diseases are transmitted by Aedes aegypti, which is widely distributed in urban areas, but whose ecology remains poorly-understood in small towns and rural settings. Methods: We surveyed aquatic habitats of Ae. aegypti mosquitoes in and around Ifakara, a fast-growing town in south-eastern Tanzania. The area was divided into 200m × 200m search grids and habitats containing immature Aedes were characterized. Field-collected Aedes were tested for susceptibility to common public health insecticides (deltamethrin, permethrin, bendiocarb and pyrimiphos methyl) in dry and rainy seasons.Results: Of 1,515 and 1,933 aquatic habitats examined in dry and rainy seasons respectively, 18.87% and 14.64% contained Aedes immatures (container index (CI): 286-283). In the 2,315 and 2,832 houses visited in dry and rainy seasons, 4.9% and 6.6% had at least one Aedes-positive habitat (house index (HI): 114-186). The main habitat types included: a) used vehicle tires and discarded containers, b) flower pots and clay pots, and c) holes made by residents on trunks of coconut trees to support climbing harvesters. Used tires had highest overall abundance of Aedes immatures, while coconut tree holes had highest densities per habitat. Ae. aegypti adults were susceptible to all tested insecticides in both seasons, except bendiocarb, against which resistance was observed in rainy season.Conclusion: This is the first study on ecology and insecticide susceptibility of Aedes in Ifakara area, and will provide a basis for future studies on its pathogen transmission activities and its control. The high infestation levels observed indicate significant risk of Aedes-borne diseases, requiring immediate action to prevent potential outbreaks in the area. While used tires, discarded containers and flower pots are key habitats for Aedes here, this study also identified coconut harvesting as an important risk factor, and the associated tree-holes as potential targets for Aedes control. Since Ae. aegypti mosquitoes in the area are still susceptible to most insecticides, effective control could combine environmental management, preferably involving communities, habitat removal and insecticide spraying.

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Urbanization creates diverse aquatic habitats for immature mosquitoes in urban areas

Scientific Reports ◽

10.1038/s41598-019-51787-5 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 8

Author(s):

André B. B. Wilke ◽

Catherine Chase ◽

Chalmers Vasquez ◽

Augusto Carvajal ◽

Johana Medina ◽

...

Keyword(s):

Aedes Aegypti ◽

Urban Areas ◽

Mosquito Control ◽

Mosquito Species ◽

Dade County ◽

Mosquito Vector ◽

Environmental Resources ◽

Aquatic Habitats ◽

Vector Species ◽

Different Types

Abstract Global increases in temperatures and urbanization are impacting the epidemiology of mosquito-borne diseases. Urbanization processes create suitable habitats for vector mosquitoes in which there are a reduced number of predators, and human hosts are widely available. We hypothesize that mosquito vector species, especially Aedes aegypti, are locally concentrated primarily in those specific habitats at the neighborhood levels that provide suitable conditions and environmental resources needed for mosquito survival. Determining how mosquito vector species composition and abundance depend on environmental resources across habitats addresses where different types of vector control need to be applied. Therefore, our goal was to analyze and identify the most productive aquatic habitats for mosquitoes in Miami-Dade County, Florida. Immature mosquito surveys were conducted throughout Miami-Dade County from April 2018 to June 2019, totaling 2,488 inspections. Mosquitoes were collected in 76 different types of aquatic habitats scattered throughout 141 neighborhoods located in the urbanized areas of Miami-Dade County. A total of 44,599 immature mosquitoes were collected and Ae. aegypti was the most common and abundant species, comprising 43% of all specimens collected. Aedes aegypti was primarily found in buckets, bromeliads, and flower pots, concentrated in specific neighborhoods. Our results showed that aquatic habitats created by anthropogenic land-use modifications (e.g., ornamental bromeliads, buckets, etc.) were positively correlated with the abundance of Ae. aegypti. This study serves to identify how vector mosquitoes utilize the resources available in urban environments and to determine the exact role of these specific urban features in supporting populations of vector mosquito species. Ultimately, the identification of modifiable urban features will allow the development of targeted mosquito control strategies optimized to preventatively control vector mosquitoes in urban areas.

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Development of a Sanitation Safety Plan for improving the sanitation system in peri-urban areas of Iringa, Tanzania

Journal of Water Sanitation and Hygiene for Development ◽

10.2166/washdev.2017.256 ◽

2017 ◽

Vol 7 (2) ◽

pp. 340-348 ◽

Cited By ~ 3

Author(s):

M. Domini ◽

G. Langergraber ◽

L. Rondi ◽

S. Sorlini ◽

S. Maswaga

Keyword(s):

Urban Areas ◽

Cost Effective ◽

Control Measures ◽

Effective Control ◽

Safety Plan ◽

First Results ◽

Assessment Matrix ◽

Planning Methodology ◽

The Given

The Sanitation Safety Planning methodology is implemented within a cooperation project in Iringa, Tanzania. The study presents the methodology and its adaptation and use for the given context, in order to assess risks and to support stakeholders in improving the current sanitation system and validate the design of an improved one. First results of the application of the methodology, obtained in one of the four peri-urban wards of Iringa, demonstrated its efficacy and utility in prioritising risks and identifying cost-effective control measures. Risks were assessed by the use of a semi-quantitative approach, and a simplified risk assessment matrix was developed for the case study. A sensitivity analysis was carried out in order to evaluate criteria for prioritising control measures to be selected for the development of an achievable improvement plan.

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Spatial Distribution of Aedes aegypti Oviposition Temporal Patterns and Their Relationship with Environment and Dengue Incidence

Insects ◽

10.3390/insects12100919 ◽

2021 ◽

Vol 12 (10) ◽

pp. 919

Author(s):

Verónica Andreo ◽

Ximena Porcasi ◽

Claudio Guzman ◽

Laura Lopez ◽

Carlos M. Scavuzzo

Keyword(s):

Time Series ◽

Spatial Distribution ◽

Aedes Aegypti ◽

Urban Areas ◽

Mosquito Species ◽

Activity Patterns ◽

Positive Association ◽

Temporal Patterns ◽

Transmission Risk ◽

Machine Learning Classification

Aedes aegypti, the mosquito species transmitting dengue, zika, chikungunya and yellow fever viruses, is fully adapted to thrive in urban areas. The temporal activity of this mosquito, however, varies within urban areas which might imply different transmission risk. In this work, we hypothesize that temporal differences in mosquito activity patterns are determined by local environmental conditions. Hence, we explore the existence of groups of temporal patterns in weekly time series of Ae. aegypti ovitraps records (2017–2019) by means of time series clustering. Next, with the aim of predicting risk in places with no mosquito field data, we use machine learning classification tools to assess the association of temporal patterns with environmental variables derived from satellite imagery and predict temporal patterns over the city area to finally test the relationship with dengue incidence. We found three groups of temporal patterns that showed association with land cover diversity, variability in vegetation and humidity and, heterogeneity measured by texture indices estimated over buffer areas surrounding ovitraps. Dengue incidence on a neighborhood basis showed a weak but positive association with the percentage of pixels belonging to only one of the temporal patterns detected. The understanding of the spatial distribution of temporal patterns and their environmental determinants might then become highly relevant to guide the allocation of prevention and potential interventions. Further investigation is still needed though to incorporate other determinants not considered here.

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Quiescence in Aedes aegypti: Interpopulation Differences Contribute to Population Dynamics and Vectorial Capacity

Insects ◽

10.3390/insects9030111 ◽

2018 ◽

Vol 9 (3) ◽

pp. 111 ◽

Cited By ~ 4

Author(s):

Luciana Oliva ◽

Roseli La Corte ◽

Marcelo Santana ◽

Cleide Albuquerque

Keyword(s):

Population Dynamics ◽

Embryonic Development ◽

Aedes Aegypti ◽

Development Time ◽

Mosquito Species ◽

Vectorial Capacity ◽

Control Measures ◽

Adult Size ◽

Egg Viability ◽

Male Predominance

The strategy of Aedes aegypti to prolong embryonic viability by quiescence has severe implications for geographic expansion and maintenance of mosquito populations in areas under control measures. We evaluated the effects of quiescence on biological parameters directly or indirectly associated with population dynamics and vectorial capacity in populations of this mosquito species from two Brazilian municipalities characterized as dengue, chikungunya, and Zika transmission areas. Egg viability, initial hatching time, post-embryonic development time, adult emergence rate, sexual proportion, adult size, fecundity, and fertility were analyzed using eggs stored for 10, 40, 70, 100, 130, and 160 d. Quiescence time reduced overall egg viability and post-embryonic development time in both municipalities but was more costly in Aracaju (100 d, 8 d) than in Recife (130 d, 7.5 d). Emergence rates increased in Recife when the eggs were older, but not in Aracaju. Significant deviations in sexual proportion, with male predominance, were observed in both populations. Initial hatch, fecundity, fertility, and adult size did not significantly influence egg quiescence time. These results indicate intrinsic and differential characteristics for each A. aegypti population, suggesting a differential cost of quiescence for population dynamics parameters that can indirectly affect vectorial capacity and control measures.

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Tree hole mosquito species composition and relative abundances differ between urban and adjacent forest habitats in northwestern Argentina

Bulletin of Entomological Research ◽

10.1017/s0007485317000700 ◽

2017 ◽

Vol 108 (2) ◽

pp. 203-212 ◽

Cited By ~ 9

Author(s):

C. Mangudo ◽

J.P. Aparicio ◽

G.C. Rossi ◽

R.M. Gleiser

Keyword(s):

Urban Areas ◽

Mosquito Species ◽

Urban Environments ◽

Negative Effects ◽

Larval Habitats ◽

Species Association ◽

Tree Hole ◽

Dengue Outbreaks ◽

Forested Areas ◽

Tree Holes

AbstractWater-holding tree holes are main larval habitats for many pathogen vectors, especially mosquitoes (Diptera: Culicidae). Along 3 years, the diversity and composition of mosquito species in tree holes of two neighbouring but completely different environments, a city and its adjacent forest, were compared using generalized linear mixed models, PERMANOVA, SIMPER and species association indexes. The city area (Northwest Argentina) is highly relevant epidemiologically due to the presence of Aedes aegypti L. (main dengue vector) and occurrence of dengue outbreaks; the Yungas rainforests are highly biologically diverse. In total seven mosquito species were recorded, in descending order of abundance: Ae. aegypti, Haemagogus spegazzinii Brèthes, Sabethes purpureus (Theobald), Toxorhynchites guadeloupensis Dyar and Knab, Aedes terrens Walker, Haemagogus leucocelaenus Dyar & Shannon and Sabethes petrocchiae (Shannon and Del Ponte). The seven mosquito species were recorded in both city sites and forested areas; however, their mosquito communities significantly diverged because of marked differences in the frequency and relative abundance of some species: Tx. guadeloupensis and Ae. aegypti were significantly more abundant in forest and urban areas, respectively. Positive significant associations were detected between Ae. aegypti, Hg. spegazzinii and Hg. leucocelaenus. The combined presence of Ae. aegypti, Haemagogus and Sabethes in the area also highlight a potential risk of yellow fever epidemics. Overall results show an impoverished tree hole mosquito fauna in urban environments, reflecting negative effects of urbanization on mosquito diversity.

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Larval habitat diversity and Anopheles mosquito species distribution in different ecological zones in Ghana

Parasites & Vectors ◽

10.1186/s13071-021-04701-w ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Isaac A. Hinne ◽

Simon K. Attah ◽

Benedicta A. Mensah ◽

Akua O. Forson ◽

Yaw A. Afrane

Keyword(s):

Lymphatic Filariasis ◽

Anthropogenic Activities ◽

Mosquito Species ◽

Larval Density ◽

Larval Habitat ◽

Effective Control ◽

Anopheles Coluzzii ◽

Ecological Zones ◽

Breeding Habitats ◽

Savannah Zone

Abstract Background Understanding the ecology of larval malaria and lymphatic filariasis mosquitoes in a changing environment is important in developing effective control tools or programmes. This study characterized the breeding habitats of Anopheles mosquitoes in rural communities in different ecological zones in Ghana during the dry and rainy seasons. Methods The spatio-temporal distribution, species composition, and abundance of larval Anopheles mosquitoes in breeding habitats were studied in five locations in three ecological zones of Ghana. These were Anyakpor (coastal savannah area), Duase (forest area), and Libga, Pagaza, and Kpalsogu (Sahel savannah area). Larvae were collected using standard dippers and were raised in the insectary for identification. Results Out of a total of 7984 mosquito larvae collected, 2152 (27.26%) were anophelines and were more abundant in the rainy season (70.82%) than in the dry season (29.18%). The anophelines comprised 2128 (98.88%) An. gambiae s.l., 16 (0.74%) An. rufipes, and 8 (0.37%) An. pharoensis. In the coastal savannah and forest zones, dug-out wells were the most productive habitat during the dry (1.59 larvae/dip and 1.47 larvae/dip) and rainy seasons (11.28 larvae/dip and 2.05 larvae/dip). Swamps and furrows were the most productive habitats in the Sahel savannah zone during the dry (0.25 larvae/dip) and rainy (2.14 larvae/dip) seasons, respectively. Anopheles coluzzii was the most abundant sibling species in all the ecological zones. Anopheles melas and An. arabiensis were encountered only in the coastal savannah and the Sahel savannah areas, respectively. Larval habitat types influenced the presence of larvae as well as larval density (p < 0.001). The land-use type affected the presence of Anopheles larvae (p = 0.001), while vegetation cover influenced larval density (p < 0.05). Conclusion The most productive habitats were dug-out wells in the coastal savannah and forest zones, and furrows from irrigated canals in the Sahel savannah zone. Anopheles coluzzii was the predominant vector species in all the ecological zones. The abundance of Anopheles breeding habitats and larvae were influenced by anthropogenic activities. Encouraging people whose activities create the larval habitats to become involved in larval source management such as habitat manipulation to stop mosquito breeding will be important for malaria and lymphatic filariasis control.

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Trend of mosquito (Diptera: Culicidae) monthly distribution in Sanandaj County of Iran

Biodiversitas Journal of Biological Diversity ◽

10.13057/biodiv/d221101 ◽

2021 ◽

Vol 22 (11) ◽

Author(s):

Bahadin Salavati ◽

AMIR HOSSEIN ZAHIRNIA ◽

Hassan Nasirian ◽

SHAHYAD AZARI-HAMIDIAN

Keyword(s):

Urban Areas ◽

Mosquito Control ◽

Mosquito Species ◽

Control Measures ◽

Adult Mosquito ◽

Rural And Urban Areas ◽

Rural And Urban ◽

Significant Difference ◽

Monthly Distribution ◽

Mosquito Breeding

Abstract. Salavati B, Zahirnia AH, Nasirian H, Hamidian SA. 2021. Trend of mosquito (Diptera: Culicidae) monthly distribution in Sanandaj County of Iran. Biodiversitas 22: 4705-4715. Mosquitoes are the most significant arthropods of medical importance due to their burden of transmitting pathogens and parasites. The present study was designed to investigate the distribution of mosquitos (Diptera: Culicidae) in Sanandaj County in 2018. Sanandaj County was divided into four areas in rural and urban areas, including north, south, east, and west. Four rural and urban areas were randomly selected from four geographical directions. A sampling of larval and adult mosquitoes was performed using standard methods. The dipping technique was used to collect the mosquito larvae. A sampling of adult mosquitoes was performed during feeding on humans and animal baits and resting in the natural indoors, outdoors, and artificial areas. Light traps were also used to collect adult mosquitoes. The larval and adult specimens were identified using the morphology-based key. In total, nine mosquito species, including Anopheles maculipennis s.l., Anopheles superpictus s.l., Culiseta longiareolata, Culiseta subochrea, Culex hortensis, Culex mimeticus, Culex modestus, Culex pipiens, and Culex theileri were inhabited in Sanandaj County. The larval and adult mosquito species trend remains constant for at least 6 months of a year, from May to October. One-way ANOVA didn't reveal a significant difference between mosquito breeding places' habitats and water types, mosquito localities and life stages, monthly mosquito distribution, and adult mosquito resting places. The frequency trends of larval and adult mosquito species remain constant at least for 6 months of a year. It needs to be ready for timely mosquito control measures.

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Key socio-economic and environmental factors in the reappearance of the Aedes aegypti mosquito in the Atacama (North Chile) Desert areas and mitigation risk measures.

10.5194/egusphere-egu2020-10413 ◽

2020 ◽

Author(s):

Mauricio Gonzalez-Pacheco ◽

Marcos Francos ◽

Angelo Olivares ◽

Xavier Úbeda

Keyword(s):

Aedes Aegypti ◽

Urban Areas ◽

Health Management ◽

Risk Measures ◽

Atacama Desert ◽

Control Measures ◽

Mitigation Measures ◽

Residential Areas ◽

Dengue Disease ◽

Extreme North

The Aedes aegypti mosquito is the main urban vector that transmits Dengue disease worldwide. In the last 25 years it has had a significant increase at a global level, reaching areas where it was eradicated, such as the reappearance in the extreme north of Chile, an area covered by the Atacama Desert. This mosquito is closely related to human settlements, which present risks that lie in the capacity of transmission of diseases caused by arboviruses by Aedes aegypti such as: Zika, Chikungunya, Yellow Fever and Dengue. The last one is the most important viral disease transmitted by mosquitoes in humans with more than 50 million estimated cases annually in over 100 countries. The aim of this study is to analyze the urban and environmental variables that determine the reappearance of the vector and to propose mitigation measures to reduce the risks of contagion. This study is located in the city of Arica (18&#176;28'28.6'' S 70&#176;17'52.5'' W) in the extreme north of the Atacama Desert, which has extraordinary habitability conditions characterized by rivers that are reactivated by summer rains in the Andes and valleys with agro-ecological productivity. The Pan American Health Organization determined the end of the presence of the mosquito in 1961 and its reappearance from 2016 in continental Chile. About the methods, the Health Authority established action limits based on the risks presented by these areas in terms of health interest and location, through inspections that allowed the identification of the vulnerability of each area. This was done by means of inspections that made it possible to identify the vulnerability of the sites. The discovery sites were geolocated according to the phenomenology of the species, considering the radius of flight among other phenological characteristics. The results allowed the identification of critical areas for the establishment of focus. The residential typologies of the sites were classified as industrial zones and suburbs in the urban limits with space-time coincidences. During 2016, 56 cases were found in urban and peri-urban areas between May and June. In 2018 there were findings between March-April with 14 cases in industrial and residential areas, while in 2019 there were findings between January-May and December with a total of 27 positive cases in peri-urban areas. In conclusion, there is evidence of a shift in findings from residential areas of paired housing (2016) to industrial areas (2018) and to suburbs in 2019. There is evidence of a deseasonalization in the findings of the mosquito, being a problem that must be controlled throughout the year. Therefore, there is an urgent need to find work methodologies that can anticipate the detection of mosquitoes in sites that present a high risk, in order to take decisions on health management and apply control measures to regulate the accumulation of water. Environmental Education is proposed as a method to promote citizen awareness to face the risks associated with the vector together with government, academic and community coordination, cooperation and collaboration.

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Tree holes as larval habitats for Aedes aegypti in urban, suburban and forest habitats in a dengue affected area

Bulletin of Entomological Research ◽

10.1017/s0007485315000590 ◽

2015 ◽

Vol 105 (6) ◽

pp. 679-684 ◽

Cited By ~ 14

Author(s):

C. Mangudo ◽

J.P. Aparicio ◽

R.M. Gleiser

Keyword(s):

Aedes Aegypti ◽

Sampling Period ◽

Larval Habitat ◽

Human Environment ◽

Larval Habitats ◽

Tree Hole ◽

Forested Areas ◽

Tree Holes ◽

Dengue Control ◽

The City

AbstractAedes aegypti (L.) (Diptera: Culicidae), the main vector of dengue and urban yellow fever in the world, is highly adapted to the human environment. Artificial containers are the most common larval habitat for the species, but it may develop in tree holes and other phytotelmata. This study assessed whether tree holes in San Ramón de la Nueva Orán, a city located in subtropical montane moist forest where dengue outbreaks occur, are relevant as larval habitat for Ae. aegypti and if the species may be found in natural areas far from human habitations. Water holding tree holes were sampled during 3 years once a month along the rainy season using a siphon bottle, in urban and suburban sites within the city and in adjacent forested areas. Larvae and pupae were collected and the presence and volume of water in each tree hole were recorded. Finding Ae. aegypti in forested areas was an isolated event; however, the species was frequently collected from tree holes throughout the city and along the sampling period. Moreover, larvae were collected in considerably high numbers, stressing the importance of taking into account these natural cavities as potential reinfestation foci within dengue control framework.

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