Skip to main content
NCBI home page
Malaria Journal logoLink to Malaria Journal
. 2026 Aug 5;25:391. doi: 10.1186/s12936-026-06076-8

First report of co-occurrence of Anopheles gambiae and An. arabiensis (Diptera: Culicidae): comparative blood meal sources and infection rates in Ethiopia

Delenasaw Yewhalaw 1,4,✉, Arega Tsegaye 2,4,✉, Gudissa Assefa 3, Alamayo Ayala 4, Mesfin Endale 4, Kassahun Zeleke 4, Mebrat Keya 4, Bezuayehu Alemayehu 5, Teshome Degefa 1,4, Eba Alemayehu 2,4, Ephrem Abiy 6, Amha Worku 6, Gedeon Yohannes 6, Dereje Olana 7, Meshesha Balkew 6
PMCID: PMC13729413  PMID: 42972403

Abstract

Background

Entomological surveillance is critical for understanding the species composition, behavior, and transmission roles of malaria vectors to guide evidence-based control strategies. This study aimed to determine the species composition, blood meal sources, and infection rates of the Anopheles gambiae complex in three regions of Ethiopia.

Methods

Surveillance was conducted from July to November 2024 in six sites across three regions (Southwest, Gambella, and Oromia) of Ethiopia. Mosquitoes were collected using human landing catches, CDC light traps, and Prokopack aspirators. Specimens were identified morphologically, followed by species-specific PCR. Blood meal sources and Plasmodium infection rates were determined using PCR and Circumsporozoite Enzyme-linked Immunosorbent Assay (CSP-ELISA), respectively.

Results

Of 284 morphologically identified An. gambiae s.l., PCR identified 39.8% as An. gambiae, 26.7% as An. arabiensis, and 6% as An. amharicus (27.8% non-amplified). Anopheles gambiae was present in all sites, with the highest prevalence in Godere (96.2%) and South Bench (60%). In contrast, An. arabiensis predominated in Seka Chekorsa (67.9%). Blood meal analysis results showed that the human blood index (HBI), bovine blood index (BBI) and goat blood index (GBI) for An. gambiae was 41.8%, 18.2% and 14.5% respectively while HBI, OBI and GBI for An. arabiesnsis was 0%, 28% and 71.4%, respectively. An. gambiae infection rates for Plasmodium falciparum and P. vivax were 2.8% and 0.9%, respectively and no Plasmodium infection was detected for An. arabiensis.

Conclusion

This study provides the first report of An. gambiae in three regions of Ethiopia and its co-occurrence with the major malaria vector, An. arabiensis was also documented for the first time in Ethiopia. The high HBI and infection rates suggest that An. gambiae could contribute to local malaria transmission in Ethiopia. Hence, the national control/elimination program should prioritize indoor residual spraying (IRS) and insecticide-treated nets (ITNs) to target this indoor-resting species (An. gambiae) in these areas.

Keywords: Anopheles gambiae, An. arabiensis, Co-occurrence, Blood meal source, Sporozoite infection rate, Ethiopia

Background

Malaria remains a significant public health challenge in Ethiopia, a country characterized by diverse ecological zones and varying malaria transmission. Approximately 75% of the landmass considered malaria-endemic, placing about 69% of the population at risk [1]. Effective malaria control and elimination strategies are critically dependent on a comprehensive understanding of the local vector fauna, including their ecology, population dynamics, distribution, abundance, and behavior of local vector species.

The Anopheles gambiae complex in Africa comprises several morphologically similar yet behaviorally and ecologically distinct sibling species. Among them, An. gambiae and An. arabiensis are major malaria vector in sub-Saharan Africa [2]. Prior to this recognition, their close morphological similarity often resulted in their erroneous grouping, hindering a clear understanding of their unique ecological niches and vectorial roles [2, 3]. Moreover, the former An. gambiae sensu stricto (s.s), has since been reclassified into An. gambiae and An. coluzzii, based on differences supported by bionomics and molecular evidence.

The accurate identification of members of the An. gambiae complex to respective sibling species across sub-Saharan Africa was greatly advanced in the late twentieth century with the introduction of molecular diagnostic techniques [4–6]. Field investigations in several sub-Saharan African countries including Cameroon, The Gambia, Liberia, and Kenya, have documented distinct patterns in the distribution and ecological preferences of An. gambiae and An. arabiensis [7–9]. For instance, An. arabiensis typically dominates in more arid and savannah regions, while An. gambiae is more prevalent in humid, forested, and wetter environments [8, 10]. These crucial findings have substantially improved our understanding of the ecology and behavior of these major malaria vectors, thereby informing the design of ecologically tailored vector control strategies across sub-Saharan Africa [11, 12].

In Ethiopia, the primary malaria vector is An. arabiensis with wide distribution in most malarious areas of the country. Other species including An. pharoensis, An. funestus and An. nili, play secondary or localized roles in malaria transmission within the country. However, the presence, vectoral status and distribution of An. gambiae in Ethiopia remain unknown.

The poor understanding of the presence and distribution of An. gambiae in Ethiopia may be attributed to a combination of factors, including mis-identification and ecological dynamics. Morphological identification alone often fails to distinguish An. gambiae from its sibling species particularly An. arabiensis, the predominant and principal malaria vector in Ethiopia. This limitation underscores the need for molecular diagnostic techniques, which however, have not been applied consistently in past entomological surveys. Even in recent studies employing molecular tools, certain limitations persist. Molecular analysis primarily targeted the most dominant species, An. arabiensis, and to some extent An. amharicus leaving some samples unidentified. In some reports, a portion of samples failed to amplify, preventing detection and accurate species level identification within the complex. Ecological factors may also contribute: An. gambiae thrives in humid West African Forests and Savannah, while in Ethiopia, diverse habitats and environmental conditions may favor An. arabiensis, which exhibits greater ecological adaptability and behavioral plasticity. Additionally, the lack of targeted intensive routine surveillance and possible competitive displacement by An. arabiensis might have further obscured the detection and distribution of An. gambiae in Ethiopia.

However, An. gambiae is predominantly anthropophilic and endophilic [13], characteristics that make it a highly efficient malaria vector and often targeted by indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) [14, 15]. The host-seeking behavior of Anopheles mosquitoes, specifically their blood meal sources, directly influences the intensity of human-vector contact and, consequently, the intensity of malaria transmission [9, 16]. Mosquitoes that primarily feed on humans (anthropophagic) pose a higher risk of transmitting malaria than those that predominantly feed on animals (zoophagic) [17, 18]. Understanding these blood-feeding patterns provides crucial insights into the entomological inoculation rate (EIR) and the potential for host diversion, where the presence of readily available and abundant animal hosts may reduce mosquito feeding on humans [19, 20]. Although mixed blood meals are generally rare in populations of An. gambiae, their occurrence indicate opportunistic feeding behaviors and offers valuable information about the species ecological adaptability [21].

Regional variations in vector species composition and feeding behaviors are well-documented in malaria-endemic areas [22, 23]. Environmental factors, such as rainfall patterns, vegetation, land use and land cover, and the availability of human and animal hosts, interventions significantly influence the abundance and distribution of different Anopheles species [24, 25]. For instance, areas with dense human populations and limited livestock might favor anthropophilic species, while pastoral or agricultural areas might favor a higher prevalence of zoophilic vectors [26, 27]. Furthermore, changes in climate and land use can alter vector habitats and impact vector species distributions over time, posing ongoing challenges for malaria control efforts [28, 29].

In countries like Ethiopia, with high ecological heterogeneity, region-specific intensive entomological surveillance is essential for the accurate identification of vector species, assessment of their biting habits, and monitoring insecticide resistance [30, 31]. Such localized entomological data is indispensable for tailored vector control strategies that maximize impact and advance malaria control and elimination targets [32]. In African settings where An. gambiae dominates, interventions like IRS and LLINs are proven highly effective due to its endophilic and anthropophagic behavior [33, 34]. However, in areas where An. arabiensis or other exophilic/zoophilic or anthropozoophilic vectors are highly prevalent, supplementary interventions such as larval source management (LSM), outdoor space spraying, or targeted use of repellents may be necessary to interrupt transmission effectively [35–37]. Therefore, continuous and intensive entomological surveillance should be implemented in Ethiopia [38, 39]. As part of routine entomological surveillance. In 2024, mosquito collections were carried out in six sites across three regions (Southwest Ethiopia, Gambella and Oromia) of Ethiopia and data on the species composition of members of the Anopheles gambiae complex, blood meal sources and sporozoite rates were presented.

Methods

Study area

Mosquito sampling was conducted in South Bench district (Southwest region), Godere and Gambella Zuria districts (Gambella region), Seka Chekorsa, Shebe Sombo and Darimu districts (Oromia region) (Fig. 1). Six Kebeles (the smallest administrative units) were selected from districts, and these were Kite from South Bench, Akash from Godere, Abol from Gambella Zuria and Bore, Kishe and Jarso from Seka Chekorsa, Shebe Sombo and Darimu, respectively. These areas are characterized by different malaria endemicity, with Gambella experiencing high perennial transmission and commonly characterized by population migration, presence of refugeees, irrigated agriculture, and environmental changes due to gold mining all of which affect the malaria transmission dynamics in that region. Notably, gold mining in the Gambella region has been associated with high malaria prevalence among migrants. In Southwest region the sites are characterized by seasonal moderate malaria transmission while in n Oromia, the study sites are located in Jimma zone (Seka Chekorsa and Shebe Sombo) and Ilubabor zone (Darimu), with seasonal low malaria transmission influenced by rainfall and altitude variation. These diverse ecological settings necessitate region-specific entomological surveillance to capture local vector species, ecology, biting and resting behaviors, and insecticide resistance patterns, to generate evidence to inform specific malaria control strategies for specific types of eco-epidemiological settings.

Fig. 1.

Fig. 1

Open in a new tab

Map showing the distribution of Anopheles gambiae in southwestern and western Ethiopia

Mosquito sampling and identification

Mosquito collections were conducted using three methods: human landing catch (HLC), CDC light traps and Prokopack aspirators. Mosquitoes were collected indoor and outdoor monthly using HLC in two randomly selected houses and compounds in Kite, Akash, Bore and Kishe, while indoor mosquito collection was carried out using CDC light traps in Abol and Jarso. Prokopack aspirators were used for Indoor and outdoor resting mosquito collection in all sites. Human volunteers recruited from the community were trained to collect mosquitoes inside houses and outdoors inside compounds 5-8 m from the selected house from 18:00 to 06:00 h. CDC light traps were hung mainly in bedrooms near sleeping individuals protected with insecticide-treated nets, about 1.5 m above the floor. CDC light traps were set to operate from 18:00 to 06:00 h. Mosquitoes collected using different methods were transported to the field laboratory for further processing. Live specimens from all collection methods were killed with chloroform, then sorted by sex and identified to species using standard morphological keys [23]. The abdominal status of adult female mosquitoes was recorded as unfed, freshly fed, half-gravid and gravid. Samples were subsequently preserved individually in labeled Eppendorf tubes over silica gel for further biochemical and molecular processing.

Molecular identification of An. gambiae complex

Morphologically identified Anopheles gambiae s.l adult mosquitoes collected by HLC, CDC light traps and Prokopack aspirators were randomly selected and identified to species using a species-specific polymerase chain reaction (PCR) assay. In brief, genomic DNA was extracted using a DNA extraction kit (Qiagen, Sigma Aldrich, USA) from whole mosquitoes. PCR amplification was carried out following established protocol [4]. PCR was performed using a Bio-Rad iCycler® with Promega® Taq DNA polymerase and its recommended 1 × buffer. Each 25 µl reaction mix contained 1 U of Taq polymerase, 0.3 mM MgCl₂, 0.08 mM dNTPs, and primers.

All primers were at 1 µM, except for QD-3T, which was used at 2 µM. For An. gambiae species identification, the thermocycling protocol began with an initial denaturation at 95 °C for 5 min. This was followed by 30 cycles of denaturation at 95 °C for 30 s, annealing at 58 °C for 30 s, and extension at 72 °C for 30 s. A final extension step was performed at 72 °C for 5 min using species-specific primers for An. arabiensis (AR: 5′-GTGTTAAGTGT CCTTCTCCGTC-3′); An. amharicus, formerly An. quadriannulatus B (QD:5′-GCATGTC CACCAACGTAAATCC-3′); An. gambiae (GA: 5′-GCTTACTGGTTTGGTCGGCATGT-3′); An. coluzzii (IMP-M1: 5′-TAG CCA GCT CTT GTC CAC TAG TTT T-3′); and a universal primer (UN: 5′-GCTGCGAGTTGT AGAGATGCG-3′). Then the amplicon was loaded on a 2% agarose gel stained with ethidium bromide and run for gel electrophoresis. Anopheles arabiensis from Sekoru insectary colony and An. amharicus from previously collected and confirmed by PCR [40] were used as positive controls.

Detection of blood meal sources

For blood meal analysis, DNA was extracted from fed and half-gravid female Anopheles mosquito abdomens. DNA was extracted from mosquito abdomens using a modified salt extraction method [41]. In brief, the abdomens were homogenized in 100 µL of an extraction buffer containing 0.1 M NaCl, 0.2 M sucrose, 0.1 M Tris–HCl, 0.05 M EDTA at pH 9.1, and 0.5% sodium dodecyl sulfate (SDS). The homogenates were then incubated at 65 °C for 1 h to facilitate cell lysis. To precipitate the SDS, 15 µL of cold 8 M potassium acetate was added to each sample, followed by incubation on ice for 45 min. After incubation, samples were centrifuged at high speed for 10 min to pellet cellular debris. DNA in the resulting supernatant was precipitated by adding 250 µL of 100% ethanol and incubating at room temperature for 5 min. The DNA was then pelleted by centrifugation for 15 min. Finally, the supernatant was discarded, and the dry DNA pellets were resuspended in a solution of 10 µL of 0.1 × SSC (15 mM NaCl, 1.5 mM sodium citrate) supplemented with 40 µL of double-distilled water.

The multiplex PCR was carried out following established protocol [42]. PCR was performed using a Bio-Rad iCycler® with Promega® Taq DNA polymerase and its recommended 1 × buffer. Each 25 µl reaction consisted of 10 mM Tris, pH 8.3, 50 mM KCl, 1.5 mM MgCl2, 0.01% gelatin, 1.0 mM dNTPs, and 0.5 units of Taq polymerase. All primers were at 1 µM, the thermocycling protocol began with an initial denaturation of 5 min at 95 °C was followed by 35 cycles at 95 °C for 1 min, 58 °C for 1 min, and 72 °C for 1 min. The final extension step was at 72 °C for 7 min. using species-specific primers for Human 741F 5′-GGCTTACTTCT CTTCATTCTCTCCT-3′, Cow121F 5′-CATCGGCACAAATTTAGTCG-3′, Goat894F 5′-CCTAATCTTAGTACTTGTACCCTTCCTC-3′, Dog368F 5′-GGAATTGTACTATTATTCGC AACCAT-3′ and a universal primer (UN: 5′-GTTGTCCTCCAATTCATGTTA-3′). Then the amplicon was loaded on a 2% agarose gel stained with ethidium bromide and run for gel electrophoresis.

Determination of mosquito infection rates

The circumsporozoite protein enzyme-linked immunosorbent assay (CSP-ELISA) was used to detect Plasmodium sporozoite infections in the heads and thoraces of mosquitoes [43]. Homogenates from the head and thorax of each mosquito were prepared and tested using the CSP ELISA kit (ATCC, Manassas, VA, USA) to detect P. falciparum, P. vivax-210 and P. vivax-247 infection.

Data analysis

For the identification of An. gambiae s.l. sibling species, the proportion of mosquitoes belonging to each sibling species was calculated, to determine their relative prevalence. Blood meal source analysis, conducted through molecular detection of host DNA for both mosquito species. The mosquito infection rate was estimated as the proportion of mosquitoes positive for P. falciparum and P. vivax CSP over the total number tested, directly measuring the potential risk of malaria transmission. Collectively, these integrated analyses provide a comprehensive understanding of the relative prevalence, feeding pattern and vectorial role of An. gambiae and An. arabiensis in the study area.

Results

Species composition

A total of 284 mosquitoes morphologically identified as An. gambiae s.l were further analyzed using species-specific PCR. These analyses revealed the presence of three sibling species, which belonged to An. gambiae, An. arabiensis and An. Amharicus (Table 1). Both An. gambiae and An. arabiensis were detected across all six sampling sites such as South Bench, Godere, Gambella Zuria, Seka Chekorsa, Shebe Sombo and Darimu, while An. amharicus was restricted to the South Bench and Darimu sites. Overall, Anopheles gambiae, An. arabiensis and An. amharicus comprised 38.9%, 26.7% and 6%, of the specimens, respectively while 27.5% the mosquito DNA samples failed to be amplified.

Table 1.

Species composition of populations of An. gambiae s.l identified by species-specific PCR from Southwest, Gambella and Oromia regions of Ethiopia (July–November 2024)

Region District (Kebele) # An. gambiae s.l tested Species identified
An. gambiae
n (%)		 An. arabiensis
n (%)		 An. amharicus
n (%)		 Non-amplified specimen
n (%)
Southwest South Bench (Kite) 53 51 (96.2) 1 (1.9) 1 (1.9) 0
Gambella Godere (Akash) 55 33 (60) 0 (0.0) 0 (0.0) 22 (40%)
Gambella Zuria (Abol) 36 10 (27.8) 9 (25) 0 (0.0) 17 (47.2)
Oromia Seka Chekorsa (Bore) 53 3 (5.7) 36 (67.9) 0 (0.0) 14 (26.4%)
Shebe Sombo (Kishe) 39 8 (20.5) 14 (35.9) 0 (0.0) 17 (43.6)
Darimu (Jarso) 48 8 (16.6) 16 (33.3) 16(33.3) 8 (16.7%)
Overall (%) 284 113 (39.8) 76 (26.7) 17(6%) 78 (27.5)
Open in a new tab

In Southwest and Gambella regions, particularly in South Bench and Godere districts, An. gambiae was predominant, constituting 96.2% and 60%, respectively. However, there was a lower proportion of An. arabiensis (26.7%) and An. amharicus (6%) in this study sites. In contrast, in Oromia region An. arabiensis was the predominant species representing 86.8%. Of all the collected specimens, An. gambiae, occurred at higher frequencies (ranging from 16.6 and 96.2%) (Fig. 2).

Fig. 2.

Fig. 2

Open in a new tab

Results of gel electrophoresis: Lanes 1, 11, 20: 100 bp ladder; Lane 2: Negative control; Lane 3: Positive control of An. gambiae (KISMU strain); Lanes 4–10: An. gambiae from the study sites; Lanes 12,13: An. arabiensis; Lanes 14–16: An. amharicus; Lanes 17–19: No DNA samples (empty wheels)

Blood meal sources

Overall, human blood was the most frequent blood meal source for An. gambiae, with a human blood index (HBI) of 41.8% followed by a bovine blood index (BBI) 18.2%, and a goat blood meal index (GBI) 14.5%. Mixed blood meals were very rare, and no human-animal mixed meals were detected. It's worth noting that a significant proportion of assayed mosquitoes (23.6%) were unamplified. Populations of An. gambiae from the Southwest region had HBI of 56.6%. On the other hand, An. arabiensis had a GBI of 71.4% and HBI of 0% (Table 2).

Table 2.

Blood meal sources of populations of An. gambiae and An. arabiensis mosquitoes detected using blood meal PCR for Southwest, Gambella and Oromia regions, Ethiopia (2024)

Region District (Kebele) # An. gambiae assayed Blood meal sources # An. arabiensis assayed Blood meal sources
+ ve Human
n (%)		 + ve Bovine
n (%)		 + ve Goat
n (%)		 + ve Dog n (%) Mixed Unamplified
n (%)		 + ve Human n (%) + ve Bovine
n (%)		 + ve Goat
n (%)		 + ve Dog
n(%)		 Mixed for
B&G
n (%)		 B&G
n (%)
Southwest South Bench (Kite) 30 17 (56.6) 3 (10.0) 5 (16.7) 0 (0.0) 0 (0.0) 5 (16.7) 1 0 (0.0) 1 (100) 0 (0.0) 0 (0.0) 0 (0.0)
Gambella Godere (Akash) 25 6 (24.0) 7 (28.0) 3 (12.0) 0 (0.0) 1 (4.0) 8(32.0) 0 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)
Oromia Seka Chekorsa (Bore) 0 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 6 0 (0.0) 1 (16.7) 5 (83.3) 0 (0.0) 0 (0.0)
Overall 55 23 (41.8) 10 (18.2) 8 (14.5) 0 (0.0) 1 (1.8) 13 (23.6) 7 0(0.0) 2 (28.6) 5 (71.4) 0 (0.0) 0 (0.0)
Open in a new tab

+ ve = Positive blood meal sources

Mosquito infection rates

A total of 109 An. gambiae and 73 An. arabiensis specimens collected from the six study sites were tested to detect circumsporozoite infections. In populations of An. gambiae from South Bench and Godere, infection rates with P.vivax and P.falciparum were 2.0% and 9.1%, respectively. The overall P. vivax and P. falciparum infection rates of populations of An. gambiae were 2.8% and 0.9%, respectively. However, none of An. arabiensis was positive for any of the Plasmodium species (Table 3).

Table 3.

Sporozoite infection rates of populations of An. gambiae and An. arabiensis from Southwest, Gambella and Oromia regions, Ethiopia (July–November 2024)

Region District (Kebele) # An. gambiae
assayed		 An. gambiae infection rates # An. arabiensis
assayed 		An. arabiensis infection rates
Pf
n (%)		 Pv210
n (%)		 Pv247
n (%)		 Pf
n (%)		 Pv 210
n (%)		 Pv247
n (%)
Southwest South Bench (Kite) 51 0 0 1 (2.0) 1 0 0 0
Gambella Godere (Akash) 53 3 (9.1) 0 0 0 0 0 0
Gambela Zuria (Abol) 10 0 0 0 9 0 0 0
Oromia Seka Chekorsa (Bore) 2 0 0 0 31 0 0 0
Shebe Sombo (Kishe) 9 0 0 0 19 0 0 0
Darimu (Jarso) 4 0 0 0 13 0 0 0
Overall 109 3 (2.8)) 0 1 (0.9) 73 0 0 0
Open in a new tab

Discussion

We report here the first occurrence of An. gambiae and its co-occurrence with An. arabiensis in three regions of Ethiopia. The high abundance of An. gambiae in Godere district of Gambella Region, aligns with observations from similar ecosystems in western Kenya and South Sudan, where this species thrives in humid, forested environments with perennial water bodies [23, 44, 45]. Such habitats provide ideal breeding sites for An. gambiae, which prefers stable, shaded pools. In contrast, the high abundance of An. arabiensis in Oromia is consistent with findings from other Ethiopian highland areas and central Tanzania, where this species adapts to drier, agricultural landscapes with temporary small water bodies ranging from hoof prints to irrigation canals [27, 46]. These disparities underscore how microclimatic and ecological factors, such as rainfall patterns and land use, drive species-specific adaptations.

The co-occurrence of An. gambiae and An. arabiensis in the study sites reflects localized ecological heterogeneity that allows for niche partitioning, a phenomenon similarly observed in the diverse ecosystems in Burkina Faso’s [47]. This sympatry poses challenges for malaria control because the two species exhibit contrasting ecology and behavior: An. gambiae is primarily endophilic and anthropophilic, making it susceptible to indoor interventions like IRS and ITNs, while An. arabiensis demonstrates more of exophilic and anthropozoophilic tendencies, which can reduce the effectiveness of these indoor-based control measures [48].

Globally, these findings align with patterns observed in West Africa, where An. gambiae dominates rainforests but declines in arid Sahelian regions, which favors An. arabiensis [49]. For effective malaria control, regional or sub-national tailored strategies are critical. In Southwest and Gambella regions of Ethiopia, IRS and ITNs should remain priorities, as demonstrated in Kenya’s high-transmission zones [50]. In Oromia region, integrating larval source management—such as larviciding irrigation channels with community-led environmental modifications could disrupt An. arabiensis breeding, mirroring successes in Eritrea [51]. Future research should address gaps in insecticide resistance profiling, particularly given that An. gambiae and An. arabiensis often exhibit distinct resistance mechanisms [52], and investigate genomic adaptations that confer resilience to climatic or anthropogenic changes.

The blood meal analysis of Anopheles mosquitoes across different regions in Ethiopia reveals critical insights into vector feeding patterns and its implications for malaria transmission dynamics. The high HBI of 41.1% observed overall, and particularly the strong anthropophilic tendency of An. gambiae in Gambella, corroborates previous findings that An. gambiae preferentially feeds on humans, thereby maintaining intense malaria transmission in such endemic areas [2, 53]. The predominance of human blood meals in Gambella, alongside the confirmed presence of An. gambiae a highly efficient malaria vector, reinforces its role as the primary driver of malaria transmission in this region [38]. The detection of bovine and ovine blood meals, albeit at lower frequencies, indicates some degree of opportunistic feeding, consistent with the known plasticity of An. gambiae in host selection depending on host availability [54]. The rare occurrence of mixed blood meals from bovine and goat in Akash, further highlights occasional opportunistic feeding on multiple hosts, a behavior documented in other African settings [9].

In contrast, An. arabiensis from Oromia region exhibits a markedly different feeding profile. The absence of human blood meals and the high bovine and dog blood meals suggest significant host diversion, which may reduce direct human-vector contact and consequently lower malaria transmission intensity in these areas [55]. This aligns with studies from other parts of Ethiopia and East Africa, where An. arabiensis exhibits plasticity in its feeding behavior, often preferring animals when readily available, thus complicating vector control efforts that rely heavely on indoor interventions [56]. The limited feeding behavior data from Oromia region, especially the absence of blood meal from several sites, suggest a significant gap, underscoring the need for more comprehensive entomological surveillance to better characterize vector–host interactions and design tailored control strategies accordingly.

The mosquito infection rates from this study provide compelling evidence that An. gambiae may have a potential role in malaria transmission in the Southwest and Gambella regions of Ethiopia. This finding aligns with An. gambiae as the most efficient and anthropophilic malaria vector in sub-Saharan Africa, particularly in humid lowland environments [2, 45]. Despite several studies from different areas of Ethiopia documented various levels of Plasmodium infection rates in An. arabiensis [57–59], the absence of sporozoite-positive in the sampled An. arabiensis in this study might be because of the small number of samples collected during the mosquito surveillance.

The higher abundance of An. gambiae among fed mosquitoes in Gambella, coupled with its confirmed sporozoite positivity and high HBI, underscores its potential role in malaria transmission in this region. This is consistent with previous studies demonstrating strong anthropophilic behavior and high vectorial capacity of this species. Conversely An. arabiensis in Oromia region showed ecological adaptation to drier and more heterogeneous environments, and it exhibited more anthropozoophilic and exophilic behaviors [56, 58, 60]. This behavioral plasticity likely reduces its vectorial efficiency as compared to An. gambiae.

In conclusion, malaria control in Ethiopia requires tailored, local-specific strategies due to differences in ecology, behavior and Plasmodium infection rates among different Anopheles mosquito vectors. In Gambella, where An. gambiae predominates, targeted IRS and enhancing coverage of ITNs is likely to reduce transmission. In contrast, An. arabiensis from Oromia region which preferred to feed on animals and rest outdoor calls for integrated vector management approaches that address these behavioral traits. Moreover, additional data on insecticide resistance status of An. gambiae in these study regions and its occurrence, ecology, behavior and infection rates in other parts of Ethiopia should be studied to implement tailored local-specific vector control intervention strategies against this vector species in Ethiopia.

Acknowledgements

The authors express thanks to all the study participants for their cooperation and dedication of time during the data collection and study period.

Author contributions

MB, DD and DY conceived and designed the study. AT MB, DD and DY are involved in the writeup of the manuscript. AA, MA, KZ, MK analysed mosquito specimens, BA, GY, AW and EA involved in supervision and data collection. DY, MB, AT, GA, EA, TD, DD critically reviewed the manuscript. All authors read and approved the manuscript.

Funding

The work was financially supported by USAID/President’s Malaria Initiative (PMI).

Data availability

The data supporting the findings of this study are available on request from the corresponding author.

Declarations

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

Footnotes

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Contributor Information

Delenasaw Yewhalaw, Email: yewhalawd@gmail.com.

Arega Tsegaye, Email: 2003arega@gmail.com.

References

  • 1.World Health Organization (WHO). (2024). Malaria Country Profile – Ethiopia, 2024. World Health Organization. https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON542. Accessed 25 Aug 2025.
  • 2.Gillies MT, De Meillon B. The Anophelinae of Africa south of the Sahara (Ethiopian zoogeographical region).
  • 3.Coluzzi M, Sabatini A, Petrarca V, Di Deco MA. Chromosomal differentiation and adaptation to human environments in the Anopheles gambiae complex. Trans R Soc Trop Med Hyg. 1979;73(5):483–97. [DOI] [PubMed] [Google Scholar]
  • 4.Wilkins EE, Howell PI, Benedict MQ. IMP PCR primers detect single nucleotide polymorphisms for Anopheles gambiae species identification, Mopti and Savanna rDNA types, and resistance to dieldrin in Anopheles arabiensis. Malar J. 2006;5(1):125. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 5.Favia G, Della Torre A, Bagayoko M, Lanfrancotti A, Sagnon NF, Touré YT, et al. Molecular identification of sympatric chromosomal forms of Anopheles gambiae and further evidence of their reproductive isolation. Insect Mol Biol. 1997;6(4):377–83. [DOI] [PubMed] [Google Scholar]
  • 6.Scott JA, Brogdon WG, Collins FH. Identification of single specimens of the Anopheles gambiae complex by the polymerase chain reaction. Am J Trop Med Hyg. 1993;49(4):520–9. [DOI] [PubMed] [Google Scholar]
  • 7.Caputo B, Nwakanma D, Jawara M, Adiamoh M, Dia I, Konate L, et al. Anopheles gambiae complex along the Gambia river, with particular reference to the molecular forms of An. gambiae ss. Malar J. 2008;7(1):182. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 8.Toure YT, Petrarca V, Traore SF, Coulibaly A, Maiga HM, Sankare O, et al. The distribution and inversion polymorphism of chromosomally recognized taxa of the Anopheles gambiae complex in Mali, West Africa. Parassitologia. 1998;40(4):477–511. [PubMed] [Google Scholar]
  • 9.Githeko AK, Adungo NI, Karanja DM, Hawley WA, Vulule JM, Seroney IK, et al. Some observations on the biting behavior of Anopheles gambiae ss, Anopheles arabiensis, and Anopheles funestus and their implications for malaria control. Exp Parasitol. 1996;82(3):306–15. [DOI] [PubMed] [Google Scholar]
  • 10.Koenraadt CJ, Githeko AK, Takken W. The effects of rainfall and evapotranspiration on the temporal dynamics of Anopheles gambiae ss and Anopheles arabiensis in a Kenyan village. Acta Trop. 2004;90(2):141–53. [DOI] [PubMed] [Google Scholar]
  • 11.Sinka ME, Bangs MJ, Manguin S, Coetzee M, Mbogo CM, Hemingway J, et al. The dominant Anopheles vectors of human malaria in Africa, Europe and the Middle East: occurrence data, distribution maps and bionomic précis. Parasit Vectors. 2010;3(1):117. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 12.Govere J, Braack LE, Durrheim DN, Hunt RH, Coetzee M. Repellent effects on Anopheles arabiensis biting humans in Kruger Park, South Africa. Med Vet Entomol. 2001;15(3):287–92. [DOI] [PubMed] [Google Scholar]
  • 13.Porciani A, Diop M, Moiroux N, Kadoke-Lambi T, Cohuet A, Chandre F, et al. Influence of pyrethroid-treated bed net on host seeking behavior of Anopheles gambiae s. s. carrying the kdr allele. PLoS ONE. 2017;12(7):e0164518. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 14.Durnez L, Coosemans M. Residual transmission of malaria: an old issue for new approaches. In: Anopheles mosquitoes: new insights into malaria vectors/Manguin, Sylvie. 2013: 671–704.
  • 15.Limwagu AJ, Msugupakulya BJ, Ngowo HS, Mwalugelo YA, Kilalangongono MS, Samli FA, et al. The bionomics of Anopheles arabiensis and Anopheles funestus inside local houses and their implications for vector control strategies in areas with high coverage of insecticide-treated nets in South-eastern Tanzania. PLoS ONE. 2024;19(12):e0295482. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 16.Service MW: Medical Entomology for Students: Cambridge University Press; 2008: 306. ISBN 978-0-521-70928-6.
  • 17.Mlacha YP, Chaki PP, Muhili A, Massue DJ, Tanner M, Majambere S, et al. Reduced human-biting preferences of the African malaria vectors Anopheles arabiensis and Anopheles gambiae in an urban context: controlled, competitive host-preference experiments in Tanzania. Malar J. 2020;19(1):418. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 18.Killeen GF, Kihonda J, Lyimo E, Oketch FR, Kotas ME, Mathenge E, et al. Quantifying behavioural interactions between humans and mosquitoes: evaluating the protective efficacy of insecticidal nets against malaria transmission in rural Tanzania. BMC Infect Dis. 2006;6(1):161. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 19.Tirados I, Costantini C, Gibson G, Torr SJ. Blood‐feeding behaviour of the malarial mosquito Anopheles arabiensis: implications for vector control. Med Vet Entomol. 2006;20(4):425–37. [DOI] [PubMed] [Google Scholar]
  • 20.Churcher TS, Lissenden N, Griffin JT, Worrall E, Ranson H. The impact of pyrethroid resistance on the efficacy and effectiveness of bednets for malaria control in Africa. Elife. 2016;5:e16090. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 21.Santos CS, Pie MR, da Rocha TC, Navarro-Silva MA. Molecular identification of blood meals in mosquitoes (Diptera, Culicidae) in urban and forested habitats in southern Brazil. PLoS ONE. 2019;14(2):e0212517. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 22.Muturi EJ, Mwangangi J, Shililu J, Jacob BG, Mbogo C, Githure J, et al. Environmental factors associated with the distribution of Anopheles arabiensis and Culex quinquefasciatus in a rice agro-ecosystem in Mwea, Kenya. J Vector Ecol. 2008;33(1):56–63. [DOI] [PubMed] [Google Scholar]
  • 23.Coetzee M, Craig M, Le Sueur D. Distribution of African malaria mosquitoes belonging to the Anopheles gambiae complex. Parasitol Today. 2000;16(2):74–7. [DOI] [PubMed] [Google Scholar]
  • 24.Lapointe DA, HE, & OP. Environmental factors influencing mosquito abundance and distribution. J Med Entomol. 2017;54(5):1157–1172.
  • 25.Endo N, Eltahir EA. Environmental determinants of malaria transmission in African villages. Malar J. 2016;15(1):578. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 26.Ashine T, Kochora A, Shibru H, Bekele A, Assefa M, Gidisa B, et al. Plasticity of blood feeding behavior of Anopheles mosquitoes in Ethiopia: a systematic review. Parasit Vectors. 2024;17(1):408. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 27.Killeen GF, Smith TA, Ferguson HM, Mshinda H, Abdulla S, Lengeler C, et al. Preventing childhood malaria in Africa by protecting adults from mosquitoes with insecticide-treated nets. PLoS Med. 2007;4(7):e229. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 28.Nazareth T, Seixas G, Sousa CA. Climate change and mosquito-borne diseases. In: Climate change and health: improving resilience and reducing risks. Cham: Springer International Publishing; 2016. p. 187–99. [Google Scholar]
  • 29.Keiser J, Utzinger J, De Castro MC, Smith TA, Tanner M, Singer BH. Urbanization in sub-Saharan Africa and implication for malaria control. American Journal of Tropical Medicine and Hygiene. Supplement to Volume 71 (2). [PubMed]
  • 30.World Health Organization (WHO). Malaria entomology and vector control: learner’s guide. WHO Press; 2013. [Google Scholar]
  • 31.Centers for Disease Control and Prevention (CDC). (2010). Entomological Surveillance. https://www.cdc.gov/malaria/malaria_worldwide/reduction/vector_control_overview.html. Accessed 23 Aug 2025.
  • 32.World Health Organization (WHO). Handbook for integrated vector management. WHO Press; 2017. [Google Scholar]
  • 33.Lengeler C. Insecticide‐treated bed nets and curtains for preventing malaria. Cochrane Database Syst Rev. 2004(2). [DOI] [PubMed]
  • 34.World Health Organization (WHO). WHO recommended insecticides for indoor residual spraying against malaria vectors. WHO Press; 2006. [Google Scholar]
  • 35.Fillinger U, Lindsay SW. Larval source management for malaria control in Africa: myths and reality. Malar J. 2011;10(1):353. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 36.Mutuku FM, King CH, Mungai P, Mbogo C, Mwangangi J, Muchiri EM, et al. Impact of insecticide-treated bed nets on malaria transmission indices on the south coast of Kenya. Malar J. 2011;10(1):356. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 37.Moore SJ, Hill N, Ruiz C, Cameron MM. Field evaluation of traditionally used plant-based insect repellents and fumigants against the malaria vector Anopheles darlingi in Riberalta, Bolivian Amazon. J Med Entomol. 2007;44(4):624–30. [DOI] [PubMed] [Google Scholar]
  • 38.Taye B, Lelisa K, Emana D, Asale A, Yewhalaw D. Seasonal dynamics, longevity, and biting activity of anopheline mosquitoes in southwestern Ethiopia. J Insect Sci. 2016;16(1):6. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 39.Adugna T, Getu E, Yewhalaw D. Species diversity and distribution of Anopheles mosquitoes in Bure district, Northwestern Ethiopia. Heliyon. 2020. 10.1016/j.heliyon.2020.e05063. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 40.Demissew A, Hawaria D, Kibret S, Animut A, Tsegaye A, Lee MC, et al. Impact of sugarcane irrigation on malaria vector Anopheles mosquito fauna, abundance and seasonality in Arjo-Didessa, Ethiopia. Malar J. 2020;19(1):344. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 41.Norris DE, Shurtleff AC, Touré YT, Lanzaro GC. Microsatellite DNA polymorphism and heterozygosity among field and laboratory populations of Anopheles gambiae ss (Diptera: Culicidae). J Med Entomol. 2001;38(2):336–40. [DOI] [PubMed] [Google Scholar]
  • 42.Kent RJ, Norris DE. Identification of mammalian blood meals in mosquitoes by a multiplexed polymerase chain reaction targeting cytochrome B. Am J Trop Med Hyg. 2005;73(2):336. [PMC free article] [PubMed] [Google Scholar]
  • 43.Wirtz RA, Burkot TR, Graves PM, Andre RG. Field evaluation of enzyme-linked immunosorbent assays for Plasmodium falciparum and Plasmodium vivax sporozoites in mosquitoes (Diptera: Culicidae) from Papua New Guinea. J Med Entomol. 1987;24(4):433–7. [DOI] [PubMed] [Google Scholar]
  • 44.Mbogo CM, Mwangangi JM, Nzovu J, Gu W, Yan G, Gunter JT, et al. Spatial and temporal heterogeneity of Anopheles mosquitoes and Plasmodium falciparum transmission along the Kenyan coast. Am J Trop Med Hyg. 2003;68(6):734–42. [PubMed] [Google Scholar]
  • 45.Coetzee M. Key to the females of Afrotropical Anopheles mosquitoes (Diptera: Culicidae). Malar J. 2020;19(1):70. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 46.Kibret S, Lautze J, McCartney M, Nhamo L, Yan G. Malaria around large dams in Africa: effect of environmental and transmission endemicity factors. Malar J. 2019;18(1):303. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 47.Dabiré KR, Diabaté A, Namountougou M, Toe KH, Ouari A, Kengne P, et al. Distribution of pyrethroid and DDT resistance and the L1014F kdr mutation in Anopheles gambiae sl from Burkina Faso (West Africa). Trans R Soc Trop Med Hyg. 2009;103(11):1113–20. [DOI] [PubMed] [Google Scholar]
  • 48.Ngonghala CN, Wairimu J, Adamski J, Desai H. Impact of adaptive mosquito behavior and insecticide-treated nets on malaria prevalence. J Biol Syst. 2020;28(02):515–42. [Google Scholar]
  • 49.Lehmann T, Licht M, Elissa N, Maega BT, Chimumbwa JM, Watsenga FT, et al. Population structure of Anopheles gambiae in Africa. J Hered. 2003;94(2):133–47. [DOI] [PubMed] [Google Scholar]
  • 50.Ototo EN, Mbugi JP, Wanjala CL, Zhou G, Githeko AK, Yan G. Surveillance of malaria vector population density and biting behaviour in western Kenya. Malar J. 2015;14(1):244. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 51.Ng’ang’a PN, Shililu J, Jayasinghe G, Kimani V, Kabutha C, Kabuage L, et al. Malaria vector control practices in an irrigated rice agro-ecosystem in central Kenya and implications for malaria control. Malar J. 2008;7(1):146. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 52.Moyes CL, Vontas J, Martins AJ, Ng LC, Koou SY, Dusfour I, et al. Contemporary status of insecticide resistance in the major Aedes vectors of arboviruses infecting humans. PLoS Negl Trop Dis. 2017;11(7):e0005625. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 53.Wangangi JM, Mbogo CM, Orindi BO, Muturi EJ, Midega JT, Nzovu J, et al. Shifts in malaria vector species composition and transmission dynamics along the Kenyan coast over the past 20 years. Malaria J. 2013;12(1):13. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 54.Takken W, Verhulst NO. Host preferences of blood-feeding mosquitoes. Annu Rev Entomol. 2013;58(1):433–53. [DOI] [PubMed] [Google Scholar]
  • 55.Midega JT, Mbogo CM, Mwambi H, Wilson MD, Ojwang G, Mwangangi JM, et al. Estimating dispersal and survival of Anopheles gambiae and Anopheles funestus along the Kenyan coast by using mark–release–recapture methods. J Med Entomol. 2007;44(6):923–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 56.Lwetoijera DW, Harris C, Kiware SS, Dongus S, Devine GJ, McCall PJ, et al. Increasing role of Anopheles funestus and Anopheles arabiensis in malaria transmission in the Kilombero Valley, Tanzania. Malar J. 2014;13(1):331. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 57.Massebo F, Balkew M, Gebre-Michael T, Lindtjørn B. Blood meal origins and insecticide susceptibility of Anopheles arabiensis from Chano in South-West Ethiopia. Parasit Vectors. 2013;6(1):44. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 58.Eligo N, Wegayehu T, Pareyn M, Tamiru G, Lindtjørn B, Massebo F. Anopheles arabiensis continues to be the primary vector of Plasmodium falciparum after decades of malaria control in southwestern Ethiopia. Malar J. 2024;23(1):14. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 59.Taye A, Hadis M, Adugna N, Tilahun D, Wirtz RA. Biting behavior and Plasmodium infection rates of Anopheles arabiensis from Sille, Ethiopia. Acta Trop. 2006;97(1):50–4. [DOI] [PubMed] [Google Scholar]
  • 60.Kenea O, Balkew M, Tekie H, Gebre-Michael T, Deressa W, Loha E, et al. Human-biting activities of Anopheles species in south-central Ethiopia. Parasit Vectors. 2016;9(1):527. [DOI] [PMC free article] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

The data supporting the findings of this study are available on request from the corresponding author.

Articles from Malaria Journal are provided here courtesy of BMC

RESOURCES