Dynamics of immature stages of Anopheles arabiensis and other mosquito species (Diptera: Culicidae) in relation to rice cropping in a rice agro-ecosystem in Kenya

2006 ◽  
Vol 31 (2) ◽  
pp. 245-251 ◽  
Author(s):  
Joseph Mwangangi ◽  
Josephat Shililu ◽  
Ephantus Muturi ◽  
Weidong Gu ◽  
Charles Mbogo ◽  
...  
Keyword(s):  
Anopheles Arabiensis ◽  
Mosquito Species ◽  
Immature Stages

scholarly journals Pre-existing Microfilarial Infections of American Robins (Passeriformes: Turdidae) and Common Grackles (Passeriformes: Icteridae) Have Limited Impact on Enhancing Dissemination of West Nile Virus in Culex pipiens Mosquitoes (Diptera: Culicidae)

2020 ◽  
Author(s):  
Jefferson A Vaughan ◽  
Juanita Hinson ◽  
Elizabeth S Andrews ◽  
Michael J Turell
Keyword(s):  
West Nile Virus ◽  
Viral Infection ◽  
Culex Pipiens ◽  
Mosquito Species ◽  
Immature Stages ◽  
West Nile ◽  
Limited Impact ◽  
Nematode Parasites ◽  
American Robins ◽  
Specific Virus

Abstract Microfilariae (MF) are the immature stages of filarial nematode parasites and inhabit the blood and dermis of all classes of vertebrates, except fish. Concurrent ingestion of MF and arboviruses by mosquitoes can enhance mosquito transmission of virus compared to when virus is ingested alone. Shortly after being ingested, MF penetrate the mosquito’s midgut and may introduce virus into the mosquito’s hemocoel, creating a disseminated viral infection much sooner than normal. This phenomenon is known as microfilarial enhancement. Both American Robins and Common Grackles harbor MF—that is, Eufilaria sp. and Chandlerella quiscali von Linstow (Spirurida: Onchocercidae), respectively. We compared infection and dissemination rates in Culex pipiens L. mosquitoes that fed on birds with and without MF infections that had been infected with West Nile virus (WNV). At moderate viremias, about 107 plaque-forming units (pfu)/ml of blood, there were no differences in infection or dissemination rates among mosquitoes that ingested viremic blood from a bird with or without microfilaremia. At high viremias, >108.5 pfu/ml, mosquitoes feeding on a microfilaremic Grackle with concurrent viremia had significantly higher infection and dissemination rates than mosquitoes fed on viremic Grackles without microfilaremia. Microfilarial enhancement depends on the specific virus, MF, and mosquito species examined. How virus is introduced into the hemocoel by MF differs between the avian/WNV systems described here (i.e., leakage) and various arboviruses with MF of the human filarid, Brugia malayi (Brug) (Spirurida: Onchocercidae) (i.e., cotransport). Additional studies are needed to determine if other avian species and their MF are involved in the microfilarial enhancement of WNV in nature.

scholarly journals Anopheles gambiae and Anopheles arabiensis population densities and infectivity in Kopere village, Western Kenya

2012 ◽  
Vol 6 (08) ◽  
pp. 637-643 ◽  
Author(s):  
Andrew Ambogo Obala ◽  
Helen L Kutima ◽  
Henry D.N. Nyamogoba ◽  
Anne W Mwangi ◽  
Chrispinus J Simiyu ◽  
...  
Keyword(s):  
Anopheles Gambiae ◽  
Malaria Vector ◽  
Anopheles Arabiensis ◽  
Mosquito Species ◽  
Sensu Stricto ◽  
Malaria Vector Control ◽  
Insecticide Treated Nets ◽  
Western Kenya ◽  
Endemic Malaria ◽  
Vector Mosquito

Introduction: This study was conducted in a sugar belt region of western Kenya interfacing epidemic and endemic malaria transmission. We investigated Anopheles gambiae sensu stricto (ss) and Anopheles arabiensis species compositions and densities, human host choice, and infectivity. Methodology: Mosquitoes were captured using pyrethrum spray catch technique and first identified based on morphology; species were confirmed by PCR. Blood meal preference and sporozoite rates were determined by ELISA. Parity rates and entomological inoculation rates (EIR) were determined. Seasonal densities were compared against environmental temperatures, relative humidity and rainfall. Results: In total 2,426 An. gambiae were collected.  Out of 1,687 female blood-fed mosquitoes, 272 were randomly selected for entomological tests. An. gambiae ss and An. arabiensis comprised 75% (205/272) and 25% (68/272) of the selection, respectively. An. gambiae ss had higher preference for human blood (97%; n=263/272) compared with An. arabiensis, which mostly fed on bovines (88%; n=239/272).  The sporozoite and parity rates were 6% (16/272) and 66% (179/272) for An. gambiae ss and 2% (4/272) and 53% (144/272) for An. arabiensis respectively, while EIR was 0.78 infective bites/person/night.  Climate (ANOVA; F=14.2; DF=23) and temperature alone (r=0.626; t=3.75; p=0.001) were significantly correlated with vector densities. Conclusion: An. gambiae ss are the most efficient malaria vector mosquito species in Kopere village. Because An. gambiae ss largely rests and feeds indoors, use of indoor residual spray and insecticide-treated nets is likely the most suitable approach to malaria vector control in Kopere village and other parts of Kenya where this species is abundant. 

scholarly journals Field Efficacy Evaluation of some Ethnomedicinal Plants Smoke Repellency Against Anopheles arabiensis and Aedes Aaegypt

2020 ◽  
Author(s):  
Abenezer Wendimu ◽  
Wondimagegnehu Tekalign
Keyword(s):  
Anopheles Arabiensis ◽  
Mosquito Species ◽  
Latin Square ◽  
Malaria Vectors ◽  
Bed Nets ◽  
Efficacy Evaluation ◽  
Mixed Powder ◽  
Plant Powders ◽  
And Control ◽  
Methods Of Application

Abstract Background: Plant products can either be used as an insecticide to kill larvae or adult mosquitoes or as defensive repellents against mosquito bites; depending on the type of activity they have. A present study was carried out to determine the repellence of smoke prepared from burning the plants in a traditional way in order to reduce human-mosquito. Methods: The candidate plant species (Azadirachta indica, Eucalyptus camaldulensis, and Ocimum forskolin) leave was grounded and mixed together in an equal amount. The mixed plant powders were checked by the thermal expulsion and burning on the traditional stoves in the field against two important malaria vectors (Anopheles arabiensis and Aedesaegypt). A four-by-four Latin-square design was used to randomly assign treatment and control experimental huts over different nights. In the treatment and control huts, the percentage repellence of the candidate plants mixed powder smoke on mosquito was determined from mosquito catches. Results: On direct burning of the plants' powder, the highest percentage repellency for An. arabiensis (94.7%, P<0.001) and Aedesaegypt (88.4%, P<0.001) recorded. On thermal expulsion also the highest against An. arabiensis (89%, P<0.001) and against Aedesaegypt (92%, P<0.001) were recorded. The plants' mixed powder tested by both methods of application offered significant protection (>85%) against two important mosquito species and thus has the potential to be used at least as an alternative way to control mosquito infestation in an easy manner in economic level.Conclusion: The two methods of application may offer cost-efficient alternatives as additional household protection and as a helpful addition to bed nets, especially for the early part of the evening before bedtime.

scholarly journals 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

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Koshila Ranasinghe ◽  
Nayana Gunathilaka ◽  
Deepika Amarasinghe ◽  
Lahiru Udayanga
Keyword(s):  
Species Richness ◽  
Sri Lanka ◽  
Disease Transmission ◽  
Mosquito Species ◽  
Breeding Habitat ◽  
Health Staff ◽  
Relative Distribution ◽  
Immature Stages ◽  
Interspecific Association ◽  
Potential Health

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.

scholarly journals Mosquito Species Composition And Insecticide Resistance Status of Anopheles Arabiensis In Itang Special Woreda, Gambella, Southwestern Ethiopia

2021 ◽  
Author(s):  
Tebiban Chanyalew ◽  
Gadisa Natea ◽  
Desalegn Amenu ◽  
Delenasaw Yewhalaw ◽  
Eba Alemayehu Simma
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Arabiensis ◽  
Mosquito Species ◽  
Light Trap ◽  
Test Procedure ◽  
Indoor Residual Spraying ◽  
World Health ◽  
Site Mutation ◽  
Southwestern Ethiopia ◽  
Pirimiphos Methyl

Abstract Introduction: Anopheles arabiensis, member species of the Anopheles gambiae complex, is the primary vector of malaria widely distributed in Ethiopia. Anopheles funestus, An. pharoensis and An. nili are secondary vectors occurring with limited distribution in the country. Indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) are pillars for the interventions against malaria control and elimination efforts in Ethiopia. However, the emergence and widespread of insecticide resistance in the major malaria vector, An. arabiensis, might compromise the efforts of the country. The aim of this study was to investigate composition of mosquito species and insecticide resistance status of An. arabiensis in Itang special woreda (district), Gambella, southwestern Ethiopia.Materials and methods: Adult mosquitoes were sampled from September 2020 to Feburary 2021 using Centers for Disease Control and Prevention (CDC) light trap and Pyrethrum Spray Catch (PSC). Moreover, mosquito larvae were also collected from different breeding sites and reared to adults to assess susceptibility status of populations of An. gambiae s.l. in the study area. Susceptibility tests were conducted on two to three days old non blood fed female An. gambiae s.l using insecticide impregnated papers with deltamethrin (0.05%), alpha-cypermethrin (0.05%), propoxur (0.1%), pirimiphos-methyl (0.25%) and bendiocarb (0.1%) following World Health Organization (WHO) standard susceptibility test procedure. Molecular diagnostics were done for the identification of member species of An. gambiae s.l and detection of knockdown resistance (kdr) allele using species specific polymerase chain reaction (PCR) and allele specific PCR. Results: In total, 468 adult mosquitoes were collected from different houses. Culex mosquitoes were the most dominant (80.4%) followed by Anopheles mosquitoes. Three species of Anopheles mosquitoes (An. coustani, An. pharoensis, and An. gambiae (s.l.)) were identified, of which An. coustani was the dominant (8.1%) species. WHO bioassay tests revealed that the populations of An. gambiae s.l in the study area are resistant against alpha-cypermethrin and deltamethrin whereas, susceptible to bendiocarb, pirimiphos-methyl and propoxur. Out of the total 86 An. gambiae s.l specimens assayed, 79 (92%) successfully amplified and identified as An. arabiensis. West African Kdr (L1014F) mutation was detected with high Kdr allele frequency ranging from 67-88%.Conclusion: The detection of target site mutation, kdr L1014F allele, coupled with the phenotypic resistance against alpha-cypermethrin and deltamethrin call for continuous resistance monitoring.

scholarly journals Impact of Aerial Humidity on Seasonal Malaria: An Ecological Study in Zambia

2021 ◽  
Author(s):  
Carolina Duque ◽  
Mukuma Lubinda ◽  
Japhet Matoba ◽  
Caison Sing'anga ◽  
Jennifer Stevenson ◽  
...  
Keyword(s):  
Malaria Case ◽  
Anopheles Arabiensis ◽  
Mosquito Species ◽  
Personal Data ◽  
Incidence Rates ◽  
Malaria Vectors ◽  
Local Health ◽  
Health Centres ◽  
Dry Seasons ◽  
Rural Zambia

Abstract Background:. Seasonal outbreaks of malaria in many parts of Africa are generally associated with rainfall; in dry seasons malaria declines but does not always cease. We postulated that aerial moisture associated with transpiration of peri-domestic trees may provide conditions to sustain pockets of mosquitoes. This study was designed to investigate this probability. Methods: Using miniature loggers designed to record moisture and temperature, set in trees and vegetation around nine selected homesteads in rural Zambia, we have shown that local tree and plant transpiration affecting the home could support the mosquito where it rests during hot dry seasons. We assessed the conditions which supported resting mosquitoes by recording the malaria case incidence rate measured at nearby health centres and clinics during the dry months. The loggers were placed in trees near the homestead with permission from the householder. No personal data were collected.Results: Data were recorded daily for three contiguous dry seasons, 2017, 2018 and 2019. The results throw a light on conditions that impact the survival of malaria vectors in arid seasons particularly in African situations and suggests how Anopheles arabiensis and other species may survive the dry seasons. Periods of nocturnal aerial moisture correlated with increase in malaria case incidence rates recorded in the local health centres. Discussion: Data were recorded daily for three contiguous dry seasons, 2017, 2018 and 2019. The results throw a light on conditions that impact the survival of malaria vectors in arid seasons particularly in African situations and suggests how Anopheles arabiensis and other species may survive the dry seasons. Periods of nocturnal aerial moisture correlated with increase in malaria case incidence rates recorded in the local health centres. The data also support the idea that mosquito species exist sporadically in widespread population demes of vector species and this likely helps repopulate habitats when the rains return.

scholarly journals Revisiting Alkali Metals As a Tool to Characterize Patterns of Mosquito Dispersal and Oviposition

Insects ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 220
Author(s):  
Matteo Marcantonio ◽  
Olivia C. Winokur ◽  
Christopher M. Barker
Keyword(s):  
Stable Isotopes ◽  
Conservation Biology ◽  
Alkali Metals ◽  
Mosquito Species ◽  
Immature Stages ◽  
Species Dispersal ◽  
Adult Females ◽  
Low Concentrations ◽  
Advanced Knowledge ◽  
Scientific Fields

Mark-recapture methods constitute a set of classical ecological tools that are used to collect information on species dispersal and population size. These methods have advanced knowledge in disparate scientific fields, from conservation biology to pest control. Gathering information on the dispersal of mosquito species, such as Aedes aegypti, has become critical since the recognition of their role as vectors of pathogens. Here, we evaluate a method to mark mosquitoes that exploits the rare alkali metals rubidium (Rb) and caesium (Cs), which have been used previously to mark adult insects through feeding. We revised this method by adding Rb and Cs directly to water in which the immature stages of Ae. aegypti were allowed to develop. We then assessed the effect of Rb- and Cs-enriched water on fitness, survival and bioaccumulation in both adult females and their eggs. Results indicated that Cs had adverse effects on Ae. aegypti, even at low concentrations, whereas Rb at low concentrations had no measured effects on exposed individuals and accumulated at detectable levels in adult females. The method described here relies on passive uptake of Rb during immature stages, which has the benefit of avoiding handling or manipulation of the dispersive adults, which enables purer measurement of movement. Moreover, we demonstrated that Rb was transferred efficiently from the marked females to their eggs. To our knowledge, Rb is the only marker used for mosquitoes that has been shown to transfer vertically from females to eggs. The application of Rb rather than more traditional markers may therefore increase the quality (no impact on released individuals) and quantity (both adults and eggs are marked) of data collected during MR studies. The method we propose here can be used in combination with other markers, such as stable isotopes, in order to maximize the information collected during MR experiments.

scholarly journals Chromosome-level genome assemblies of the malaria vectors Anopheles coluzzii and Anopheles arabiensis

GigaScience ◽  
2021 ◽  
Vol 10 (3) ◽  
Author(s):  
Anton Zamyatin ◽  
Pavel Avdeyev ◽  
Jiangtao Liang ◽  
Atashi Sharma ◽  
Chujia Chen ◽  
...  
Keyword(s):  
Anopheles Arabiensis ◽  
De Novo ◽  
Mosquito Species ◽  
Sub Saharan Africa ◽  
Malaria Vectors ◽  
Anopheles Coluzzii ◽  
Reference Quality ◽  
Sub Saharan ◽  
Genome Assemblies ◽  
Chromosome Level

Abstract Background Anopheles coluzzii and Anopheles arabiensis belong to the Anopheles gambiae complex and are among the major malaria vectors in sub-Saharan Africa. However, chromosome-level reference genome assemblies are still lacking for these medically important mosquito species. Findings In this study, we produced de novo chromosome-level genome assemblies for A. coluzzii and A. arabiensis using the long-read Oxford Nanopore sequencing technology and the Hi-C scaffolding approach. We obtained 273.4 and 256.8 Mb of the total assemblies for A. coluzzii and A. arabiensis, respectively. Each assembly consists of 3 chromosome-scale scaffolds (X, 2, 3), complete mitochondrion, and unordered contigs identified as autosomal pericentromeric DNA, X pericentromeric DNA, and Y sequences. Comparison of these assemblies with the existing assemblies for these species demonstrated that we obtained improved reference-quality genomes. The new assemblies allowed us to identify genomic coordinates for the breakpoint regions of fixed and polymorphic chromosomal inversions in A. coluzzii and A. arabiensis. Conclusion The new chromosome-level assemblies will facilitate functional and population genomic studies in A. coluzzii and A. arabiensis. The presented assembly pipeline will accelerate progress toward creating high-quality genome references for other disease vectors.

scholarly journals Rift Valley fever virus (family Bunyaviridae, genus Phlebovirus). Isolations from Diptera collected during an inter-epizootic period in Kenya

1985 ◽  
Vol 95 (1) ◽  
pp. 197-209 ◽  
Author(s):  
K. J. Linthicum ◽  
F. G. Davies ◽  
A. Kairo ◽  
C. L. Bailey
Keyword(s):  
Adult Male ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Mosquito Species ◽  
Transovarial Transmission ◽  
Immature Stages ◽  
Valley Fever ◽  
Virus Family ◽  
Male And Female

SUMMARYA total of 134876 Diptera collected in Kenya during a 3-year period were tested in 3383 pools for Rift Valley fever (RVF) virus. Nineteen pools of unengorged mosquitoes were found positive for RVF. All isolations were made from specimens collected at or near the naturally or artificially flooded grassland depressions that serve as the developmental sites for the immature stages of many mosquito species. The isolation of virus from adult male and female A. lineatopennis which had been reared from field-collected larvae and pupae suggests that transovarial transmission of the virus occurs in this species.

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