scholarly journals Time of Test Periods Influence the Behavioral Responses of Anopheles minimus and Anopheles dirus (Diptera: Culicidae) to DEET

Insects ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 867
Author(s):  
Rungarun Tisgratog ◽  
Chutipong Sukkanon ◽  
Victor Arief Sugiharto ◽  
Michael J. Bangs ◽  
Theeraphap Chareonviriyaphap
Keyword(s):  
Mosquito Species ◽  
Behavioral Responses ◽  
Test System ◽  
Malaria Vectors ◽  
Anopheles Dirus ◽  
Anopheles Species ◽  
Anopheles Minimus ◽  
Significant Difference ◽  
Escape Responses ◽  
The Impact

Information on factors influencing the behavioral responses of mosquitoes to repellents is lacking and poorly understood, especially in the Anopheles species, night-biting mosquitoes. Our goal was to investigate the impact of different time periods on circadian activity and behavioral responses of two malaria vectors, Anopheles minimus and An. dirus, to 5% DEET using an excito-repellency test system. Each mosquito species was exposed to the repellent during the daytime (06.00–18.00) and nighttime (18.00–06.00), and time of observation was further divided into four 3-h intervals. Significant escape responses were observed between daytime and nighttime for An. minimus in both noncontact and contact tests. An. dirus showed statistical differences in contact irritancy escape response, whereas no significant difference was found in noncontact repellency tests. Both mosquito species showed more significantly higher escape responses when exposed to DEET during the afternoon and late in the night. This finding indicates that the time of testing may affect the behavioral responses of mosquitoes to repellents, especially in An. minimus and An. dirus. A better understanding of nocturnally active mosquito behavioral responses spanning from dusk to dawn would assist in optimizing product development, screening, and effective evaluation.

scholarly journals The impact of transfluthrin on the spatial repellency of the primary malaria mosquito vectors in Vietnam: Anopheles dirus and Anopheles minimus

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Nicholas J. Martin ◽  
Vu S. Nam ◽  
Andrew A. Lover ◽  
Tran V. Phong ◽  
Tran C. Tu ◽  
...  
Keyword(s):  
Vector Control ◽  
Large Scale ◽  
Limit Of Detection ◽  
Malaria Vectors ◽  
Adult Mosquito ◽  
Anopheles Dirus ◽  
Anopheles Minimus ◽  
Control Programmes ◽  
The Impact ◽  
Spatial Repellency

Abstract Background The complexity of mosquito-borne diseases poses a major challenge to global health efforts to mitigate their impact on people residing in sub-tropical and tropical regions, to travellers and deployed military personnel. To supplement drug- and vaccine-based disease control programmes, other strategies are urgently needed, including the direct control of disease vectors. Modern vector control research generally focuses on identifying novel active ingredients and/or innovative methods to reduce human-mosquito interactions. These efforts include the evaluation of spatial repellents, which are compounds capable of altering mosquito feeding behaviour without direct contact with the chemical source. Methods This project examined the impact of airborne transfluthrin from impregnated textile materials on two important malaria vectors, Anopheles dirus and Anopheles minimus. Repellency was measured by movement within taxis cages within a semi-field environment at the National Institute of Hygiene and Epidemiology in Hanoi, Vietnam. Knockdown and mortality were measured in adult mosquito bioassay cages. Metered-volume air samples were collected at a sub-set of points in the mosquito exposure trial. Results Significant differences in knockdown/mortality were observed along a gradient from the exposure source with higher rates of knockdown/mortality at 2 m and 4 m when compared with the furthest distance (16 m). Knockdown/mortality was also greater at floor level and 1.5 m when compared to 3 m above the floor. Repellency was not significantly different except when comparing 2 m and 16 m taxis cages. Importantly, the two species reacted differently to transfluthrin, with An. minimus being more susceptible to knockdown and mortality. The measured concentrations of airborne transfluthrin ranged from below the limit of detection to 1.32 ng/L, however there were a limited number of evaluable samples complicating interpretation of these results. Conclusions This study, measuring repellency, knockdown and mortality in two malaria vectors in Vietnam demonstrates that both species are sensitive to airborne transfluthrin. The differences in magnitude of response between the two species requires further study before use in large-scale vector control programmes to delineate how spatial repellency would impact the development of insecticide resistance and the disruption of biting behaviour.

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

2020 ◽  
Author(s):  
Assalif Demissew Shifera ◽  
Dawit Hawaria ◽  
Solomon Kibret ◽  
Abebe Animut ◽  
Arega Tsegaye ◽  
...  
Keyword(s):  
Species Composition ◽  
Malaria Vector ◽  
Mosquito Species ◽  
Malaria Vectors ◽  
Anopheline Mosquito ◽  
Chi Square ◽  
Anopheles Species ◽  
Mosquito Abundance ◽  
Anopheles Mosquitoes ◽  
The Impact

Abstract Background: Although irrigation activities are increasing in Ethiopia, limited studies evaluated their impact on malaria vector mosquito composition, abundance and seasonality. This study aimed at evaluating the impact of sugarcane irrigation on species composition, abundance and seasonality of malaria vectors. Methods : Adult 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. Mosquito collections were conducted 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 identified to species using morphological keys and An. gambiae s.l to sibling species using PCR. Chi-square was used to analyze the association between Anopheles species occurrence and environmental and seasonal parameters. Results: Overall, 2,108 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. An. gambiae s.l was the most abundant (67.3%) followed by An. coustani complex (25.3 %) and An. pharoensis (5.7%). PCR based identification revealed that 74.7% (n=168) of the An. gambiae s.l were An. arabiensis and 22.7% (n=51) An. amharicus . Density of An. gambiae s.l. (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). Conclusion : The ongoing sugarcane irrigation activities in Arjo-Didessa created conditions suitable for increased malaria transmitting Anopheles species diversity and abundance. This in turn could drive malaria transmission in Arjo-Didessa and its environs in both dry and wet seasons. Thus, currently practiced malaria vector interventions need to be strengthened and consider larval source management to reduce vector abundance in the irrigated areas. Key Words: Malaria, Irrigation, Anopheles mosquitoes, vector density, An. amharicus , Ethiopia

scholarly journals Anopheles Bionomics in a Malaria Endemic Area of Southern Thailand

2021 ◽  
Author(s):  
Narenrit Wamaket ◽  
Oranicha Khamprapa ◽  
Sittinont Chainarin ◽  
Panisa Thamsawet ◽  
Ubolrat Ninsaeng ◽  
...  
Keyword(s):  
Molecular Identification ◽  
Malaria Vectors ◽  
Power Calculation ◽  
Chi Square ◽  
Anopheles Dirus ◽  
Significant Difference ◽  
Southern Thailand ◽  
Human Landing ◽  
Greater Mekong Subregion ◽  
The Impact

Abstract Background: Ivermectin mass drug administration (MDA) could accelerate malaria elimination in the Greater Mekong Subregion. This study was performed to characterize the bionomics of Anopheles in Surat Thani province, Thailand.Methods: Mosquitoes were collected via human landing collections, February - October of 2019. Anopheles were morphologically identified to species. Primary Anopheles malaria vectors were dissected to assess parity status and a subset evaluated for molecular identification and Plasmodium detection.Results: A total of 17,348 mosquitoes were collected. Of 5,777 Anopheles mosquitoes, 15 species were identified morphologically. The most abundant Anopheles were Anopheles minimus s.l. (87.87%, n = 5,035), Anopheles dirus s.l. (7.05%, n = 407), and Anopheles barbirostris s.l. (2.86%, n = 165). Molecular identification confirmed that of An. minimus s.l., 99.80% were An. minimus s.s. (n=484) and 0.2% An. aconitus (n = 1), of An. dirus s.l., 100% were An. baimaii (n = 348), and of An. maculatus s.l., 93.62% were An. maculatus s.s. (n = 44) and 6.38% An. sawadwongporni (n = 3). No Anopheles were Plasmodium positive (n = 879). An average of 11.46 Anopheles were captured per collector per night. There were differences between species in hour of collection (Kruskal-Wallis = 80.89, P < 0.0001, n = 5,666), with more An. barbirostris s.l. and An. maculatus s.l. caught earlier compared to An. minimus s.l. (P = 0.0001, P < 0.0001, respectively) and An. dirus s.l. (P = 0.0082, P < 0.001, respectively). The proportion of parous An. minimus s.l. captured by hour increased throughout the night (Wald Chi-square = 17.31, P=0.000, odds ratio = 1.0535 [1.0279 – 1.0796] 95% CI (n = 3,400). Overall, An. minimus s.l. parity was 67.68% (2,375/3,509) with an intra cluster correlation of 0.0378. A power calculation determined that an An. minimus s.l. parity reduction treatment effect size = 34%, with four clusters per treatment arm, a minimum of 300 mosquitoes dissected per cluster at an α= 0.05 will provide 82% power to detect a significant difference following ivermectin MDA. Conclusions: The study area in Surat Thani province is an ideal location to evaluate the impact of ivermectin MDA on An. minimus parity.

scholarly journals Impact of Sugarcane Irrigation on Malaria Vector Anopheles Mosquito Fauna, Abundance and Seasonality in Arjo-Didessa, Ethiopia

2020 ◽  
Author(s):  
Assalif Demissew Shifera ◽  
Dawit Hawaria ◽  
Solomon Kibret ◽  
Abebe Animut ◽  
Arega Tsegaye ◽  
...  
Keyword(s):  
Species Composition ◽  
Malaria Vector ◽  
Mosquito Species ◽  
Malaria Vectors ◽  
Anopheline Mosquito ◽  
Chi Square ◽  
Anopheles Species ◽  
Mosquito Abundance ◽  
Anopheles Mosquitoes ◽  
The Impact

Abstract Background: Although irrigation activities are increasing in Ethiopia, limited studies evaluated their impact on malaria vector mosquito composition, abundance and seasonality. This study aimed at evaluating the impact of sugarcane irrigation on species composition, abundance and seasonality of malaria vectors. Methods: Adult 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. Mosquito collections were conducted 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 identified to species using morphological keys and An. gambiae s.l to sibling species using PCR. Chi-square was used to analyze the association between Anopheles species occurrence and environmental and seasonal parameters. Results: Overall, 2,108 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. An. gambiae s.l was the most abundant (67.3%) followed by An. coustani complex (25.3 %) and An. pharoensis (5.7%). PCR based identification revealed that 74.7% (n=168) of the An. gambiae s.l were An. arabiensis and 22.7% (n=51) An. amharicus. Density of An. gambiae s.l. (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). Conclusion: The ongoing sugarcane irrigation activities in Arjo-Didessa created conditions suitable for increased malaria transmitting Anopheles species diversity and abundance. This in turn could drive malaria transmission in Arjo-Didessa and its environs in both dry and wet seasons. Thus, currently practiced malaria vector interventions need to be strengthened and consider larval source management to reduce vector abundance in the irrigated areas.

BEHAVIORAL RESPONSES TO DDT AND PYRETHROIDS BETWEEN ANOPHELES MINIMUS SPECIES A AND C, MALARIA VECTORS IN THAILAND

2005 ◽  
Vol 73 (2) ◽  
pp. 343-349 ◽  
Author(s):  
JINNAPA POTIKASIKORN ◽  
THEERAPHAP CHAREONVIRIYAPHAP ◽  
MICHAEL J. BANGS ◽  
ATCHARIYA PRABARIPAI
Keyword(s):  
Behavioral Responses ◽  
Malaria Vectors ◽  
Anopheles Minimus

scholarly journals Rapid ageing and species identification of natural mosquitoes for malaria surveillance

2020 ◽  
Author(s):  
Doreen J. Siria ◽  
Roger Sanou ◽  
Joshua Mitton ◽  
Emmanuel P. Mwanga ◽  
Abdoulaye Niang ◽  
...  
Keyword(s):  
Mosquito Species ◽  
Natural Populations ◽  
Cost Effective ◽  
Malaria Vectors ◽  
Sampling Effort ◽  
Malaria Surveillance ◽  
Vector Borne Diseases ◽  
Vector Borne ◽  
Species Specific ◽  
The Impact

AbstractThe malaria parasite, which is transmitted by several Anopheles mosquito species, requires more time to reach its human-transmissible stage than the average lifespan of a mosquito. Monitoring the species-specific age structure of mosquito populations is critical to evaluating the impact of vector control interventions on malaria risk. We developed a rapid, cost-effective surveillance method based on deep learning of mid-infrared spectra of mosquitoes’ cuticle that simultaneously identifies the species and the age of three main malaria vectors, in natural populations. Using over 40,000 ecologically and genetically diverse females, we could speciate and age grade An. gambiae, An. arabiensis, and An. coluzzii with up to 95% accuracy. Further, our model learned the age of new populations with minimal sampling effort and detected the impact of control interventions on simulated mosquito populations, measured as a shift in their age structures. We anticipate our method to be applied to other arthropod vector-borne diseases.

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

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Assalif Demissew ◽  
Dawit Hawaria ◽  
Solomon Kibret ◽  
Abebe Animut ◽  
Arega Tsegaye ◽  
...  
Keyword(s):  
Species Composition ◽  
Malaria Vector ◽  
Mosquito Species ◽  
Molecular Techniques ◽  
Malaria Vectors ◽  
Anopheline Mosquito ◽  
Chi Square ◽  
Mosquito Abundance ◽  
Southwestern Ethiopia ◽  
The Impact

Abstract Background Despite 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. Methods Adult 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. Results Overall, 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). Conclusion The 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.

Behavioral Responses of Malaria Vectors, Anopheles minimus Complex, to Three Classes of Agrochemicals in Thailand

2007 ◽  
Vol 44 (6) ◽  
pp. 1032-1039 ◽  
Author(s):  
Jinrapa Pothikasikorn ◽  
Hans Overgaard ◽  
Chitapa Ketavan ◽  
Surapon Visetson ◽  
Michael J. Bangs ◽  
...  
Keyword(s):  
Behavioral Responses ◽  
Malaria Vectors ◽  
Anopheles Minimus

scholarly journals Molecular Characterization and Genotype Distribution of Thioester-containing Protein 1 Gene, A Key Regulator of Malaria Transmission in An. Gambiae Mosquitoes in Western Kenya

2021 ◽  
Author(s):  
Shirley A. Onyango ◽  
Kevin O. Ochwedo ◽  
Maxwell G. Machani ◽  
Collince J. Omondi ◽  
Isaiah Debrah ◽  
...  
Keyword(s):  
Population Structure ◽  
Anopheles Gambiae ◽  
Malaria Transmission ◽  
Mosquito Species ◽  
Malaria Vectors ◽  
Fixation Index ◽  
Genotype Distribution ◽  
Low Frequencies ◽  
Western Kenya ◽  
Significant Difference

Abstract BackgroundEvolutionary pressures lead to the selection of efficient malaria vectors either resistant or susceptible to Plasmodiumparasites.These forcesmay elevate the introduction of new species genotypes that adapt to new breeding habitats which could have serious implications on malaria transmission.Thioester-containing protein 1 (TEP1) of Anopheles gambiaeplays an important role in innate immune defenses against parasites. This study aims to characterize the distribution pattern of TEP1 polymorphisms determining vector competence and subsequently malaria transmission in western Kenya. MethodsAnopheles gambiaeadult and larvae were collected using pyrethrum spray catches (PSC) and plastic dippers respectivelyfrom Homa Bay, Kakamega, Bungoma, and Kisumu countiesbetween 2017 and 2020.Collected adults and larvae reared to the adult stage were morphologically identified and then identified to sibling species by PCR.TEP1 alleles were determined using restriction fragment length polymorphisms-polymerase chain reaction (RFLP-PCR) and to validate the TEP1 genotyping results, a representative sample of alleles was sequenced.ResultsTwo TEP1 alleles (TEP1*S1 and TEP1*R2)and three corresponding genotypes (*S1/S1, *R2/S1, and *R2/R2)were identified. TEP1*S1 and TEP1*R2 with their corresponding genotypes, homozygous *S1/S1 and heterozygous *R2/S1 were widely distributed across all sites with allele frequencies of approximately 80% and 20%, respectively bothin An. gambiaeand An. arabiensis. There was no significant difference detected among the population and between the two mosquito species in TEP1 allele frequency and genotype frequency. The overall low levels in population structure (FST= 0.019) across all sites corresponded to an effective migration index (Nm= 12.571) and lowNei’s genetic distance values (<0.500) among the subpopulation.The comparative fixation index values revealed minimal genetic differentiation between speciesand high levels of gene flow among populations.ConclusionThere is a low genetic diversity and population structure in western Kenya. TEP1* R2 and TEP1*S1 were the most common alleles in both species which may have been maintained through generations in time, However, the TEP1*R2 allele was in low frequencies and may be used to estimatemalaria prevalence. Continued surveillance of the distribution of TEP1 is essential for monitoring the population dynamics of local vectors and their implications on malaria transmission and hence designing targeted vector interventions.

Molecular Identification of Anopheles minimus sensu lato and Anopheles dirus sensu lato (Diptera: Culicidae) from Kampong Spoe Province, Cambodia

Zootaxa ◽  
2005 ◽  
Vol 1028 (1) ◽  
pp. 37 ◽  
Author(s):  
YAJUN MA ◽  
SOK VANNE ◽  
SHIZHU LI ◽  
PIN YANG
Keyword(s):  
Internal Transcribed Spacer ◽  
Malaria Vectors ◽  
Sequence Variant ◽  
Sequence Variants ◽  
Anopheles Dirus ◽  
Anopheles Minimus ◽  
The Third ◽  
Species Complexes ◽  
Second Internal Transcribed Spacer ◽  
First Time

Anopheles dirus and An. minimus are primary malaria vectors in Cambodia. Both are species complexes and can be confused on the basis of adult morphology. The second internal transcribed spacer (ITS2) and the third domain (D3) in 28S of ribosomal DNA (rDNA) of An. minimus sensu lato and An. dirus s. l. were sequenced and analyzed. Three species (An. minimus A, An. sawadwongporni, and An. pampanai) and three sequence variants (MYJ-1, MYJ-2 and MYJ-3) were identified in An. minimus s. l. Two species (An. dirus A, An. pampanai) and one sequence variant (MYJ-1) were identified in An. dirus s. l. Anopheles sawadwongporni is recorded for the first time in Cambodia.

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