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 ◽  
Molecular Techniques ◽  
Malaria Vectors ◽  
Chi Square ◽  
Mosquito Abundance ◽  
Southwestern Ethiopia ◽  
Four Seasons ◽  
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 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. 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, 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 malaria transmitting Anopheles species diversity and abundance. This 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 by including larval source management to reduce vector abundance in the irrigated areas.

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.

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 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.

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 ◽  
Molecular Techniques ◽  
Anopheline Mosquito ◽  
Anopheles Species ◽  
Gambiae Complex ◽  
Mosquito Abundance ◽  
Anopheles Mosquitoes ◽  
The Impact

Abstract BackgroundDespite extensive irrigation development in Ethiopia, limited studies assessed the impact of irrigation on malaria vector mosquito composition, abundance and seasonality. This study aimed to evaluate the impact of sugarcane irrigation on species composition, abundance and seasonality of malaria vectors.MethodsAdult Anopheles mosquitoes were collected using CDC light traps from three irrigated and three non-irrigated clusters in and around Arjo-Didessa sugarcane irrigation scheme in southwestern Ethiopia. Mosquitoes were surveyed in four seasons: two wet and two dry, in 2018 and 2019. Mosquito species composition, abundance and seasonality were compared between irrigated and non-irrigated clusters. Anopheles mosquitoes were sorted out to species using morphological keys and molecular techniques. Chi-square was used to test the relationships between Anopheles species occurrence, and environmental and seasonal parameters.ResultsOverall, 2,108 female Anopheles mosquitoes comprising of six species were collected. Of these, 92.7% (n=1,954) 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 comlex 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=1,837) was higher than the dry seasons (12.8%; n=271).ConclusionThe ongoing sugarcane irrigation activities in Arjo-Didessa created conditions suitable for malaria transmitting Anopheles species diversity and abundance. This could drive malaria transmission in Arjo-Didessa and its environs in both dry and wet seasons. Currently practiced malaria vector interventions need to be strengthened by including larval source management to reduce vector abundance in the irrigated areas.

scholarly journals Malaria vector species composition and relative abundance in Mutare and Mutasa districts, Zimbabwe

2015 ◽  
Vol 47 (3) ◽  
pp. 79 ◽  
Author(s):  
S. Sande ◽  
M. Zimba ◽  
P. Chinwada ◽  
H.T. Masendu ◽  
A. Makuwaza
Keyword(s):  
Species Composition ◽  
Relative Abundance ◽  
Malaria Vector ◽  
Sibling Species ◽  
Mosquito Species ◽  
Sensu Stricto ◽  
Malaria Vectors ◽  
Morphological Identification ◽  
Vector Species ◽  
Vector Behaviour

Regular entomological monitoring is important to determine changes in mosquito species composition and relative densities of malaria vectors in relation to vector control interventions. A study to gain insights into malaria vector species composition and relative abundance was undertaken in Mutare and Mutasa districts, Zimbabwe. Two methods; indoor resting catches and larval sampling were used to collect indoor resting adults and larvae from May 2013 to April 2014. Mosquitoes collected as adults and reared from larvae that were identified morphologically as potential malaria vectors were further processed to sibling species by polymerase chain reaction (PCR). Morphological identification of anopheline mosquitoes showed presence of two complexes: <em>An. funestus</em> and <em>An. gambiae</em>. The total number of female members of the <em>An. funestus</em> group and <em>An. gambiae</em> complex collected by both methods from the two sites was 840 and 31 respectively. Malaria vector species of both complexes were more abundant in Mutare than in Mutasa. The PCR-based assays showed the presence of four sibling species: <em>An. funestus</em> <em>sensu</em> <em>stricto</em> (90.8%, 267/294) and <em>An. leesoni</em> (5.1%, 15/294), of <em>An. funestus</em> group; <em>An. arabiensis</em> (41.9%, 13/31) and <em>An. quadriannulatus</em> (48.4%, 15/31) of the <em>An. gambiae</em> complex. About 4% and 5% of specimens of <em>An. gambiae</em> complex and A<em>n. funestus</em> group respectively did not amplify. Of the two identified malaria vector sibling species, An. funestus sensu stricto was more abundant (95.4%, 267/280) than <em>An. arabiensis</em> (4.6%, 13/280), suggesting the replacement to secondary vector of <em>An. arabiensis</em>, which was previously the predominant vector species. <em>An. funestus</em> <em>sensu</em> <em>stricto</em> and <em>An</em>. <em>arabiensis</em>, the most important vectors of human malaria were identified in this study, but their resting and biting habits as well as insecticide susceptibility are unclear. Further studies on vector behaviour are therefore recommended.

scholarly journals Malaria vector species composition and entomological indices following indoor residual spraying in regions bordering Lake Victoria, Tanzania

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Charles Kakilla ◽  
Alphaxard Manjurano ◽  
Karen Nelwin ◽  
Jackline Martin ◽  
Fabian Mashauri ◽  
...  
Keyword(s):  
Species Composition ◽  
Vector Control ◽  
Malaria Vector ◽  
Lake Victoria ◽  
Indoor Residual Spraying ◽  
Transmission Risk ◽  
Malaria Vectors ◽  
Vector Species ◽  
Sporozoite Rate ◽  
Pirimiphos Methyl

Abstract Background Vector control through long-lasting insecticidal nets (LLINs) and focal indoor residual spraying (IRS) is a major component of the Tanzania national malaria control strategy. In mainland Tanzania, IRS has been conducted annually around Lake Victoria basin since 2007. Due to pyrethroid resistance in malaria vectors, use of pyrethroids for IRS was phased out and from 2014 to 2017 pirimiphos-methyl (Actellic® 300CS) was sprayed in regions of Kagera, Geita, Mwanza, and Mara. Entomological surveillance was conducted in 10 sprayed and 4 unsprayed sites to determine the impact of IRS on entomological indices related to malaria transmission risk. Methods WHO cone bioassays were conducted monthly on interior house walls to determine residual efficacy of pirimiphos-methyl CS. Indoor CDC light traps with or without bottle rotator were hung next to protected sleepers indoors and also set outdoors (unbaited) as a proxy measure for indoor and outdoor biting rate and time of biting. Prokopack aspirators were used indoors to capture resting malaria vectors. A sub-sample of Anopheles was tested by PCR to determine species identity and ELISA for sporozoite rate. Results Annual IRS with Actellic® 300CS from 2015 to 2017 was effective on sprayed walls for a mean of 7 months in cone bioassay. PCR of 2016 and 2017 samples showed vector populations were predominantly Anopheles arabiensis (58.1%, n = 4,403 IRS sites, 58%, n = 2,441 unsprayed sites). There was a greater proportion of Anopheles funestus sensu stricto in unsprayed sites (20.4%, n = 858) than in sprayed sites (7.9%, n = 595) and fewer Anopheles parensis (2%, n = 85 unsprayed, 7.8%, n = 591 sprayed). Biting peaks of Anopheles gambiae sensu lato (s.l.) followed periods of rainfall occurring between October and April, but were generally lower in sprayed sites than unsprayed. In most sprayed sites, An. gambiae s.l. indoor densities increased between January and February, i.e., 10–12 months after IRS. The predominant species An. arabiensis had a sporozoite rate in 2017 of 2.0% (95% CI 1.4–2.9) in unsprayed sites compared to 0.8% (95% CI 0.5–1.3) in sprayed sites (p = 0.003). Sporozoite rates were also lower for An. funestus collected in sprayed sites. Conclusion This study contributes to the understanding of malaria vector species composition, behaviour and transmission risk following IRS around Lake Victoria and can be used to guide malaria vector control strategies in Tanzania.

scholarly journals Evaluation of mosquito electrocuting traps as a safe alternative to the human landing catch for measuring human exposure to malaria vectors in Burkina Faso

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Antoine Sanou ◽  
W. Moussa Guelbéogo ◽  
Luca Nelli ◽  
K. Hyacinth Toé ◽  
Soumanaba Zongo ◽  
...  
Keyword(s):  
Species Composition ◽  
Burkina Faso ◽  
Malaria Vector ◽  
Human Exposure ◽  
Infected Mosquito ◽  
Malaria Vectors ◽  
Human Landing Catch ◽  
Mosquito Vector ◽  
Human Landing ◽  
Biting Behaviour

Abstract Background Measuring human exposure to mosquito bites is a crucial component of vector-borne disease surveillance. For malaria vectors, the human landing catch (HLC) remains the gold standard for direct estimation of exposure. This method, however, is controversial since participants risk exposure to potentially infected mosquito bites. Recently an exposure-free mosquito electrocuting trap (MET) was developed to provide a safer alternative to the HLC. Early prototypes of the MET performed well in Tanzania but have yet to be tested in West Africa, where malaria vector species composition, ecology and behaviour are different. The performance of the MET relative to HLC for characterizing mosquito vector population dynamics and biting behaviour in Burkina Faso was evaluated. Methods A longitudinal study was initiated within 12 villages in Burkina Faso in October 2016. Host-seeking mosquitoes were sampled monthly using HLC and MET collections over 14 months. Collections were made at 4 households on each night, with METs deployed inside and outside at 2 houses, and HLC inside and outside at another two. Malaria vector abundance, species composition, sporozoite rate and location of biting (indoor versus outdoor) were recorded. Results In total, 41,800 mosquitoes were collected over 324 sampling nights, with the major malaria vector being Anopheles gambiae sensu lato (s.l.) complex. Overall the MET caught fewer An. gambiae s.l. than the HLC (mean predicted number of 0.78 versus 1.82 indoors, and 1.05 versus 2.04 outdoors). However, MET collections gave a consistent representation of seasonal dynamics in vector populations, species composition, biting behaviour (location and time) and malaria infection rates relative to HLC. As the relative performance of the MET was somewhat higher in outdoor versus indoor settings, this trapping method slightly underestimated the proportion of bites preventable by LLINs compared to the HLC (MET = 82.08%; HLC = 87.19%). Conclusions The MET collected proportionately fewer mosquitoes than the HLC. However, estimates of An. gambiae s.l. density in METs were highly correlated with HLC. Thus, although less sensitive, the MET is a safer alternative than the HLC. Its use is recommended particularly for sampling vectors in outdoor environments where it is most sensitive.

scholarly journals Cytochrome P450 metabolic resistance (CYP6P9a) to pyrethroids imposes a fitness cost in the major African malaria vector Anopheles funestus

Heredity ◽  
2020 ◽  
Vol 124 (5) ◽  
pp. 621-632 ◽  
Author(s):  
Magellan Tchouakui ◽  
Jacob Riveron Miranda ◽  
Leon M. J. Mugenzi ◽  
Doumani Djonabaye ◽  
Murielle J. Wondji ◽  
...  
Keyword(s):  
Malaria Vector ◽  
Management Strategy ◽  
Management Strategies ◽  
Resistance Management ◽  
Anopheles Funestus ◽  
Fitness Cost ◽  
Malaria Vectors ◽  
Hybrid Strain ◽  
Metabolic Resistance ◽  
The Impact

Abstract Metabolic resistance threatens the sustainability of pyrethroid-based malaria control interventions. Elucidating the fitness cost and potential reversal of metabolic resistance is crucial to design suitable resistance management strategies. Here, we deciphered the fitness cost associated with the CYP6P9a (P450-mediated metabolic resistance) in the major African malaria vector Anopheles funestus. Reciprocal crosses were performed between a pyrethroid susceptible (FANG) and resistant (FUMOZ-R) laboratory strains and the hybrid strains showed intermediate resistance. Genotyping the CYP6P9a-R resistance allele in oviposited females revealed that CYP6P9a negatively impacts the fecundity as homozygote susceptible mosquitoes (CYP6P9a-SS) lay more eggs than heterozygote (OR = 2.04: P = 0.01) and homozygote resistant mosquitoes. CYP6P9a also imposes a significant fitness cost on the larval development as homozygote resistant larvae (CYP6P9a-RR) developed significantly slower than heterozygote and homozygote susceptible mosquitoes (χ2 = 11.2; P = 0.0008). This fitness cost was further supported by the late pupation of homozygote resistant than susceptible mosquitoes (OR = 2.50; P < 0.01). However, CYP6P9a does not impact the longevity as no difference was observed in the life span of mosquitoes with different genotypes (χ2 = 1.6; P = 0.9). In this hybrid strain, a significant decrease of the resistant CYP6P9a-RR genotype was observed after ten generations (χ2 = 6.6; P = 0.01) suggesting a reversal of P450-based resistance in the absence of selection. This study shows that the P450-mediated metabolic resistance imposes a high fitness cost in malaria vectors supporting that a resistance management strategy based on rotation could help mitigate the impact of such resistance.

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 Host-seeking behavior and hourly biting rhythm of vectors in malaria endemic district of Arba Minch area, Southwest Ethiopia

2020 ◽  
Author(s):  
Melkam Abiye Zeru ◽  
Simon Shibru ◽  
Fekadu Massebo
Keyword(s):  
Malaria Vector ◽  
Negative Binomial ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Southwest Ethiopia ◽  
Anopheles Mosquitoes ◽  
Host Seeking ◽  
Human Landing ◽  
Seeking Behavior ◽  
The Impact

Abstract Background The early and outdoor biting behaviors of malaria vectors are among the key challenges in malaria control. Hence, understanding the host-seeking behavior and the peak biting time of malaria vectors is important in malaria vector control programs. This study assessed the host-seeking behavior and hourly biting activity of malaria mosquitoes in Chano Mille village in Arba Minch district, southwest Ethiopia. Methods The first trial was done by keeping cattle together with human that collects the entered mosquitoes in tent, while the other was done by keeping cattle outside a 1 m distance from human collector inside a tent. In both trials, mosquito collation was done inside tents baited by cattle and human using human landing catches (HLC) techniques. Four human volunteers’ were recruited and trained to collect mosquitoes in the four tents from 18:00-24:00 for three months. Two tents were selected randomly for human alone and two for cattle baited collections in the first night and then rotated to minimize the variation due to location of tents and collectors skill. The tent trial was done close to the shore of the Lake Abaya to minimize the interference of other animals on mosquito movement. The peak biting hour of malaria vectors was assessed within a Chano village from 18:00-6:00. Mosquito collation was done both indoor and outdoor by HLC. Morphological speciation of Anopheles mosquitoes was done. The sporozoite infectivity status of Anopheles pharoensis was examined using enzyme-linked immuno-sorbent assay technique. The data was analyzed using a Generalized Estimating Equations with a negative binomial distribution. Results An. pharoensis, An. gambiae complex and An. tenebrosus were the three species documented during the trial. Keeping cattle together with human collector inside the tent attracted 42% ( P < 0.001) more An. pharoensis compared to human alone tent. Also, keeping cattle outside near to a tent with human at 1 m distance, attracted the entering An. pharoensis into the tent inside with human by 46% ( P = 0.002) than human in a tent with no cattle outside the same tent. The impact was not significant for An. gambiae complex and An. tenebrosus. Anopheles pharoensis and An. gambiae complex showed early night biting activity with peak biting from 19.00-20:00 which was significant for both An. gambiae complex ( P < 0.001) and An. pharoensis ( P = 0.015). Anopheles gambiae complex was mainly biting humans outdoor in the village. Conclusions Finally, keeping cattle within and close to human dwellings could increase malaria vectors bite exposure particularly to the zoophilic malaria vector An. pharoensis and, hence deployment of cattle far from human residence could be recommended to reduce the human exposure. The outdoor and early hours biting behavior of the An. gambiae complex could be a threat for success of current indoor based interventions and hence, tools could be designed to reduce this threat.

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