Invasion of the Dengue Vector Aedes albopictus in the Port City of Takoradi, Southwestern Ghana

Invasion of the Dengue Vector Aedes albopictus in the Port City of Takoradi, Southwestern Ghana | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Invasion of the Dengue Vector Aedes albopictus in the Port City of Takoradi, Southwestern Ghana Faustina Adobea Owusu, Christopher Mfum Owusu-Asenso, Anisa Abdulai, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7407322/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract In mid-2023, Aedes albopictus , a key dengue vector, was unexpectedly identified during Anopheles surveillance in Takoradi, southwestern Ghana. Ae. albopictus is not known to be breeding in Ghana until this encounter. By mid-2024, the Ghana Health Service reported several outbreaks of dengue for the first time, with confirmed cases in several regions, including Takoradi. This study investigated the bionomics and insecticide susceptibility of Ae. albopictus through larval and adult surveys near the initial detection sites, including the seaport. Among 2,666 Aedes larvae collected, car tyres were the most productive habitat (66.4%). Ae. aegypti (87.2%) were the most abundant vector, followed by Ae. albopictus (12.2%). Ae. albopictus was fully susceptible to pyrethroids and pirimiphos-methyl, while Ae. aegypti was resistant to pyrethroids. PBO synergist assays restored susceptibility in Ae. aegypti . kdr mutations were detected in both species: Ae. albopictus had low frequencies of F1534C (0.18), V410L (0.02), V1016I (0.00) whilst Ae. aegypti showed high F1534C (0.72), V1016I (0.50), and V410L (0.06). These findings provide essential baseline data for public health action and necessitate the urgent need for enhanced vector surveillance and resistance monitoring in Ghana. Health sciences/Diseases Biological sciences/Ecology Earth and environmental sciences/Ecology Biological sciences/Microbiology Biological sciences/Zoology Aedes albopictus Aedes aegypti Invasive species Insecticide resistance kdr mutations Ghana Figures Figure 1 Figure 2 Figure 3 Figure 4 Background Over the past few decades, Aedes albopictus , also known as the Asian tiger mosquito, has expanded its range from its native habitats in Southeast Asia to various regions across the world including Africa 1 , 2 , 3 . Its invasion has been attributed to human-mediated activities such as the international trade of tyres 4 and climate change 5 , 6 , which provide ideal breeding habitats and enabling the species to establish and thrive in diverse ecological settings. The vector's adaptability to different climatic conditions, its ecological plasticity and ability to outcompete native mosquito species has facilitated its establishment across the African continent 7 . Aedes albopictus is an efficient vector of dengue fever and has been implicated in the increased outbreak of dengue and other arboviral diseases in Africa 8 , 9 , 10 . In West Africa, where urbanization is accelerating, the rapid invasion and establishment of the dengue vector Ae. albopictus poses a significant risk of outbreak and sustained transmission of arboviral diseases, particularly in densely populated cities with limited vector control programs 9 . Recent reports suggest an alarming increase in dengue cases across the sub-Saharan region; Nigeria, Côte d'Ivoire, Burkina Faso and Togo 11 , 12 , 13 , 14 . Ghana shares its geographical borders with these countries, signifying the growing threat posed by the disease. In Ghana, after the initial discovery of a single Aedes albopictus at the University of Ghana Legon campus 15 , another study found Aedes albopictus larvae in Madina, Accra 16 . However, till date, there is paucity of data on the ecology and insecticide resistance profiles of the Aedes albopictus in Ghana and their potential role in arboviral disease transmission. Interestingly, in September 2023, an entomological surveillance focused on Anopheles mosquitoes in Takoradi in the Western Region of Ghana led to the unexpected finding of the highly invasive vector Aedes albopictus in significant numbers in Apowa, a peri-urban area about 10 km away from the Takoradi port. This incidental finding may indicate the invasion and establishment of the dengue vector in the region, raising concerns about its potential role in dengue transmission. A few months later, the Ghana Health Service reported several outbreaks of dengue in Ghana for the first time in July 2024 17 . Moreover, studies in West and Central Africa, including Côte d'Ivoire, Benin, Cameroon and the Central African Republic have reported insecticide resistance in Ae. albopictus populations 2 , 3 , 18 , 19 , signaling the potential for similar challenges in Ghana. Recognizing the increasing threat posed by Ae. albopictus , the World Health Organization has emphasized the need for integrated vector surveillance and control strategies to mitigate its spread 20 . In alignment with these recommendations, this study provides baseline data into the vector’s population dynamics and insecticide resistance in Takoradi, Ghana. Results Distribution and abundance of Aedes Larval Habitats. During the study period, a total of 450 larval habitats with 50 positive breeding habitats for Aedes mosquitoes were identified across the study areas. The positive breeding habitats surveyed comprised of five (5) distinct habitat types, all of which were man-made. The most abundant habitat type was car tyres (62.0%) followed by discarded containers (16.0%), drums (8.0%), buckets (8.0%), and jerry cans (6.0%), (Table 1 ). Relative to seasons, results obtained showed that more larval habitats were encountered in the rainy season (n = 33, 66%) as compared to the dry season (n = 17, 34%) (ꭓ 2 = 3.31, df = 4, P = 0.5). All positive Aedes breeding habitats (n = 50, 100.0%) encountered during the study period were located outdoors (Table 1 ). Table 1 Distribution and Abundance of Larval Habitats. Habitat type Count of habitat type Dry (%) Rainy (%) Total (%) Bucket 2 (50.0) 2 (50.0) 4 (100.0) Discarded container 3 (37.5) 5 (62.5) 8 (100.0) Drum 2 (50.0) 2 (50.0) 4 (100.0) Jerry can 2 (66.7) 1 (33.3) 3 (100.0) Car tyre 8 (25.8) 23 (74.2) 31 (100.0) Total 17 (34.0) 33 (66.0) 50 (100.0) Abundance of Aedes Larval in the Breeding Habitats A total of 2,666 Aede s mosquito larvae were collected from the surveyed breeding habitats. The most productive habitat was car tyres 66.4% (1,771) ( F = 1.06, df = 4, P = 0.50) (Table 2 ). A relatively high abundance of Aedes immatures were sampled during the rainy season, 65.8% (1,755), whereas 34.2% (911) were collected during the dry season ( t = 0.04, df = 48, P = 0.96). The highest larval abundance was recorded in Apowa across both seasons (n = 2,184, 81.9%) ( F = 2.36, df = 2, P = 0.50), (Table 2 ). Table 2 The seasonal distribution of Aedes larvae across the study sites. Container type Apowa Takoradi Port Dry (%) Rainy (%) Dry (%) Rainy (%) Drum 97 (10.6) 173 (13.6) 0 (0.0) 0 (0.0) Discarded container 145 (15.9) 144 (11.3) 0 (0.0) 103 21.4) Jerry can 70 (7.7) 72 (5.7) 0 (0.0) 0 (0.0) Car tyre 583 (64.0) 809 (63.6) 0 (0.0) 379 (78.6) Bucket 16 (1.8) 75 (5.9) 0 (0.0) 0 (0.0) Total 911 (100.0) 1,273 (100.0) 0 (0.0) 482 (100.0) Larval samples collected from the study areas, which emerged into adult Aedes mosquitoes were morphologically identified as Aedes aegypti (97.3%) and Aedes albopictus (2.3%), (Table 3 ). Aedes aegypti larvae were collected from both study areas, while Aedes albopictus larvae were specifically obtained from car tires in the Takoradi Port and its surrounding areas (Table 3 ). Table 3 Morphological Identification of Emerged Aedes Mosquitoes Study sites Ae. aegypti (%) Ae. albopictus (%) Total (%) Apowa 460 (100.0) 0 (0.0) 460 (100.0) Takoradi Port 250 (92.6) 20 (7.4) 270 (100.0) Total 710 (97.3) 20 (2.7) 730 (100.0) Adult Aedes mosquito distribution A total of 1,268 mosquitoes belonging to three different genera were sampled during the study; Aedes (n = 960, %), Culex (n = 288, %) and Anopheles (n = 3, %). Out of the total 960 adult Aedes mosquitoes sampled during the study, Aedes aegypti (n = 837; 87.2%) was the most predominant species by morphological identification, this was followed by Aedes albopictus (n = 117; 12.2%) and then Aedes chemulpoensis (n = 6; 0.6%). Site-specific species distribution showed that, a high abundance of Aedes mosquitoes were sampled in Apowa (n = 443; 46.1%) [ Aedes aegypti (n = 371; 83.7%), Aedes albopictus (n = 66; 14.9%), Aedes chemulpoensis (n = 6; 1.4%)] (Table 4 ). Table 4 Morphological Identification of Adult Aedes Abundance Study sites Ae. aegypti (%) Ae. albopictus (%) Ae. chemulpoensis (%) Total (%) Apowa 371 (83.7) 66 (14.9) 6 (1.4) 443 (100.0) Takoradi Port 352 (87.3) 51 (12.7) 0 (0.00) 403 (100.0) Anaji 114 (100.0) 0 (0.00) 0 (0.00) 114 (100) Total 837 (87.2) 117 (12.2) 6 (0.6) 960 (100) Significantly higher numbers of Aedes mosquitoes we sampled during the rainy season (n = 730; 76.0%) [Takoradi Port (n = 354; 48.5%), Apowa (n = 262; 35.9%), Anaji (n = 114; 15.6%)] (Fig. 2a) compared to the dry season n = 230; 24.0%) [Apowa (n = 181; 78.7%), Takoradi Port (n = 49; 21.3%), Anaji (n = 0; 0%)], ( t = -2.29, df = 275, P = 0.011). Significantly high abundance of Aedes mosquitoes were collected outdoors (n = 909; 94.7%) as compared to indoor collection 51 (5.3%), ( t = -5.31, df = 275, P < 0,001). Apowa recorded the highest indoor collections (n = 47; 92.6%), while most mosquitoes collected outdoor were from Takoradi Port (n = 399; 41.6%) (Fig. 2b). A high abundance (n = 923) of host-seeking Aedes mosquitoes (mosquitoes sampled using HLC + BG traps) were sampled over the entire sampling period, with a high abundance (n = 858) of actively biting (mosquitoes collected using HLC) Aedes mosquitoes ( F = 26.55, P < 0.001). (Fig. 3). Overall, a total of 37 resting mosquitoes were collected using PPK aspirators (Fig. 3). Insecticide Susceptibility and Synergist Assays Phenotypic resistance results showed that the Aedes albopictus mosquito population was susceptible to Deltamethrin (Mortality rate (MR) = 98.8%), Permethrin (MR = 100.0%), and Pirimiphos-methyl (100.0%). In comparison, the Aedes aegypti population showed resistance to pyrethroids (Permethrin (74.3%); Deltamethrin (MR = 75.0%)) and full susceptibility to Pirimiphos-methyl (MR = 100.0%) (ꭓ 2 = 230, df = 2, P = < 0.001) (Fig. 4a). However, preexposure of Aedes aegypti mosquito to PBO before the bioassay, restored full susceptibility of the mosquito population to pyrethroids (ꭓ 2 = 79, df = 1, P = < 0.001) (Fig. 4b). Genotypic Resistance of Aedes mosquitoes A sub-sample of 103 field-caught Aedes mosquitoes [ Ae. albopictus = 53; Ae. aegypti = 50] were randomly selected and subjected to allele-specific PCR to detect the presence of kdr mutations F1534C , V1016I and V410L . Low allelic frequencies of F1534C (F = 0.18) (ꭓ 2 = 16.09, P < 0.001), V410L (F = 0.02) (ꭓ 2 = 0.02, P = 0.89) and V1016I (F = 0.00) were detected in Ae . albopictus . However, high allelic frequency (F = 0.66) of F1534C (ꭓ 2 = 1.26, P = 0.26) and V1016I (F = 0.50) (ꭓ 2 = 50, P < 0.001) and a much lower allelic frequency (F = 0.06) of V410L (ꭓ 2 = 0.20, P = 0.65) mutations was observed in Ae. aegypti (Table 5 ). Table 5 Number of genotypes and frequencies of the V1016I , F1534C and V410L mutations in the voltage-gated sodium channel gene of adult Aedes aegypti and Aedes albopictus mosquitoes. N F1534C V410L V1016I Species CC FF FC F LL VV VL F II VV VI F Aedes albopictus 53 6 40 7 0.18 0 51 2 0.02 0 53 0 0.00 Aedes aegypti 50 20 4 26 0.66 0 44 6 0.06 0 0 50 0.50 Total 103 26 44 33 0 95 8 0 53 50 (CC, II, LL-Kdr; FF, VV-wild-type; FC, VI, VL-Heterozygote, F; Allelic frequency, N; number) Genotypic analysis of Aedes albopictus and Aedes aegypti mosquitoes from bioassays revealed relatively high frequencies of F1534C (Allelic frequency (F) = 0.75) and V1016I (F = 0.50) in deltamethrin-susceptible Ae. albopictus mosquitoes, while all three kdr mutations ( F1534C , V1016I , and V410L ) were present at relatively high frequencies in deltamethrin-resistant Ae. albopictus mosquitoes (Table 6 ). Similarly, a high frequency of F1534C (F = 0.70) was detected in deltamethrin-susceptible Ae. aegypti mosquitoes, with moderate to low frequencies of V1016I (F = 0.40) and V410L (F = 0.15) respectively. Deltamethrin-resistant Ae. aegypti haboured relatively high frequencies of F1534C (F = 0.68) and V1016I (F = 0.50), with low frequency of V410L (F = 0.25). For permethrin-susceptible Ae. albopictus , relatively high to low levels of V1016I (F = 0.50) and F1534C (F = 0.25) was observed respectively. No V410L mutation was detected. In contrast, Ae. aegypti mosquitoes exhibited higher frequencies of all three kdr mutations in permethrin-susceptible and resistant populations (Table 6 ). Table 6 Allelic frequencies of the V1016I, F1534C and V410L mutations in the voltage-gated sodium channel gene of Aedes aegypti and Aedes albopictus mosquitoes from WHO Bioassays. Insecticide Species Resistant genes (F) Phenotype N F1534C V410L V1016I Deltamethrin Ae. albopictus S 30 0.75 0.03 0.50 R 1 0.50 0.50 0.50 Ae. aegypti S 30 0.70 0.15 0.40 R 30 0.68 0.25 0.50 Permethrin Ae. albopictus S 30 0.25 0.00 0.50 R 0 0 0 0 Ae. aegypti S 30 0.82 0.73 0.50 R 30 0.87 0.60 0.50 (S; Susceptible, R; Resistant, N; number, F; Allelic frequency) Discussion Due to its highly invasive nature and capability of transmitting several globally important arboviruses such as Dengue, Chikungunya, Yellow fever and Zika, the invasion of Aedes albopictus in Ghana poses a significant public health threat. This study showed the detection of a significant number of Ae. albopictus in Takoradi, and its environs implying an invasion event that may be ongoing. The invasive vector however, showed susceptibility to insecticides that could be used for its control. This study provides baseline data crucial for public health action on invasive Ae. Albopictus that could be crucially involved in the transmission of arboviral disease in Ghana. The detection of the highly invasive species, Aedes albopictus in significant numbers in Takoradi, in the port, its environs and outside of the city represents a critical entomological finding with substantial implications for arboviral disease transmission in Ghana. Ports are well-documented entry points for invasive mosquito species 21 . The global movement of goods, via maritime transport, has been linked to the transcontinental spread of Ae. albopictus through used car tyres 22 . It was shown in the current study that this invasive vector is breeding more in car tires. This invasive species could spread to other parts of Ghana through transport routes that are linked to the port. Given the species’ known vector competence for dengue, chikungunya, yellow fever, and Zika viruses 23 , its establishment in Ghana poses a significant public health concern. The emergence of Aedes albopictus across multiple study sites in Ghana coincided with reports of confirmed dengue outbreaks in several places in the country, including Southwestern Ghana by the Ghana Health Service 17 . While our current data do not establish a transmission link, the temporal overlap between the emergence of this invasive species and the surge in dengue cases raises critical questions. There is a big gap to ascertain potential involvement of Ae. albopictus in ongoing dengue transmission outbreaks. Understanding the role and extent to which this species contributes to dengue transmission is essential. While Ae. aegypti remains the dominant urban vector, the introduction of Ae. albopictus , a competent dengue vector, could alter transmission dynamics. Its behavioral plasticity, ecological shift of the previously sylvatic vector into urban areas, and ability to exploit diverse breeding habitats enhance its adaptability and survival in diverse environments, potentially increasing its role in arboviral transmission dynamics. These traits not only allow Ae. albopictus to thrive under varying ecological pressures but also position it to potentially displace native Ae. aegypti populations. A similar trend has been reported in the Republic of Congo, where Ae. albopictus has overtaken Ae. aegypti as the dominant urban vector 24 , 25 , 26 , 27 . Such displacement, coupled with the co-circulation of multiple Aedes species, may intensify arboviral transmission risks and complicate control strategies in endemic settings The WHO bioassays revealed full susceptibility of Ae. albopictus to pyrethroids and organophosphates. The susceptibility of these vectors may imply that insecticide-based control strategies could still yield high operational efficacy against this emerging vector, particularly in areas where it is newly established. This observation may suggest a critical advantage for effective vector control before the development and spread of resistance and establishment and expansion of Ae. albopictus populations. This finding was consistent with another study from Benin 18 . The low phenotypic resistance observed may be attributable to the species’ relatively minimal prior exposure to insecticides and recent urban establishment. Contrary to the finding reported for Ae. albopictus , Ae. aegypti populations were resistant to pyrethroids, with full susceptibility restored after pre-exposure to PBO, suggesting metabolic resistance mechanisms may be involved. This is consistent with prior reports in Ghana, where pre-expose of pyrethroid resistant Aedes aegypti to PBO, restored susceptibility 28 . Conclusion This study is the first to provides a baseline assessment of the invasion of Ae. albopictus and its insecticide resistance status in Ghana, and highlights the significant risk posed by this vector in arboviral disease transmission. Enhanced entomological and molecular surveillance is needed at major ports of entry and high-risk urban centers in Ghana to ascertain their involvement in the ongoing dengue transmission in Ghana, as well as the extent of the invasion. Materials and Methods Study sites This study was conducted in three (3) localities Southwestern part of Ghana; Apowa (4°53’0” N, 1°49’0” W), Anaji (4°54'16'' N, 2°6'51” W), and the Takoradi Port and surrounding areas (4°54'00'' N, 1°44'00'' W) to investigate the distribution, behavior, and insecticide resistance profiles of Aedes albopictus . Apowa where Ae. albopictus was first found accidentally in significant numbers became a focal site, while Anaji and the Takoradi port and its surrounding areas were selected to assess potential spread and introduction points of this invasive species (Fig. 1). The sea port at Takoradi receives all sorts of shipment including cars, car tyres, car spare parts, from all over the world. This may pose a substantial risk of introducing and establishing the Ae. albopictus and other invasive species into the port and its surrounding areas, which may increase the potential for arboviral transmission. The extensive transportation networks linking Takoradi to other regions of Ghana could facilitate the rapid spread of Ae. albopictus and its associated pathogens. The accidental detection of Ae. albopictus was in Apowa, and was selected as a study site following the citing of a significant abundance of Ae. albopictus within this area. Apowa, a peri-urban area in the Ahanta West Municipal District is situated about 10 km away from the Takoradi port and 6 km from Anaji. Anaji is a residential suburb situated within the Sekondi‑Takoradi metropolitan area. Anaji lies approximately 4 km west of central Takoradi, the regional capital. Anaji is about 8 km north-west to the Takoradi port. The site was selected to ascertain the spread of the dengue vector away from the port and Apowa. Vector sampling in Anaji was done only in the rainy season due to logistics reason. From each of these sites with the exception of Anaji, both larval and adult collections were conducted during the rainy and dry seasons from September 2023 to February 2024. However, only the surrounding areas of the Takoradi port was sampled during the dry season, since the team was not able to acquire clearance to enter the port premises. After receiving clearance and collaborations with the Takoradi Port Health, the area within and around the port were sampled during the rainy season. With an average annual temperature of 26.5°C and a mean yearly rainfall of 787 mm, the selected study areas which are located in the coastal savannah region of Southwestern Ghana, has a tropical savannah weather pattern. The region has a bimodal rainfall pattern, with the long rainy season occurring from April to June and the minor one from October to November. This study was approved by the Ethics and Protocol Review Committee of the College of Health Sciences, University of Ghana (protocol identification number: CHS-Et/M.9-P4.3/2023–2024). All methods were carried out in accordance with relevant guidelines and regulations, including the ethical principles outlined in the Declaration of Helsinki for medical research. Meetings were held at each study site with chiefs, community leaders, and residents to introduce the research. Permission to conduct the study at the various sites was obtained from community leaders. Verbal informed consent was obtained from community leaders and residents for mosquito sampling activities. Mosquito sampling and characterization of Aedes breeding habitats Extensive larval surveys were conducted from September 2023 to February 2024 in these study sites to locate water-holding containers (e.g., tyres, jerry cans, drums) in and around human habitations and inspected for Aedes immatures. The habitat type, its location within a household (whether indoor or outdoor) was recorded. All potential Aedes breeding containers were examined for the presence of Aedes immature and recorded in each site. Using pipettes and ladles, immature stages (field generation, Fo) were collected from containers positive for Aedes mosquitoes including vehicle tyres, drums, jerry cans, tanks, buckets and abandoned containers. For each sampling site, Aedes immatures were pooled in plastic larval bowls and transferred to the insectary at the Department of Medical Microbiology, University of Ghana. Larvae obtained were fed with TetraMin Baby fish food (Tetra Werke, Melle, Germany) throughout their development. Upon emergence into adults, they were morphologically identified using standard taxonomic keys 29 . Once identified as Ae. aegypti or Ae. albopictus , mosquitoes of the same species and from the same locality were pooled into separate individual cages. Due to their low abundance, Ae. albopictus mosquitoes were reared to their first filial generation (F 1 ) for adult bioassays. At the insectary, mosquito populations were maintained under controlled environmental conditions (relative humidity: 80 ± 10%, temperature: 27 ± 2°C) and females were fed on rabbits to complete their gonotrophic cycle. The geographic coordinates of all sampling sites were documented with a geographical position system (GPSMAP® 60CSx). Adult Aedes mosquito collections To determine the spatial distribution and vector behaviour of adult Aedes mosquitoes, sampling was conducted indoors and outdoors of houses at each site using three sampling techniques; the BG-Sentinel 2 traps (BG trap) (Biogents AG, Weissenburgstr 22, 93055 Regensburg, Germany), Human landing catches (HLC) and Prokopack Aspirators (PPK) (John W. Hock Company, Gainesville, U.S.A.). At each study site, from the hours of 4:00 pm to 7:00 pm, the BG traps were positioned indoors (in bedrooms and living rooms) and outdoors (on open verandas, or under sheds/ trees where people gather, approximately 5 meters from the home). The traps were baited with CO 2 , which was a mixture made by adding 17.5 g of yeast (Angel Yeast (Egypt) Co. Ltd.) and 250 g of sugar to 1 liter of water 30 . For the HLC sampling technique, trained volunteers acted as both baits and catchers. Four trained volunteers (two stationed indoors and two others outdoors) collected host-seeking Aedes mosquitoes daily between the hours 4:00pm to 7:00pm. Prokopack aspiration was employed to mechanically aspirate indoor and outdoor resting Aedes mosquitoes. The Aedes mosquitoes collected were stored in clearly labelled paper cups after which they were transported to the insectary for identification and molecular analysis. Collected Aedes mosquitoes were knocked down with chloroform and preserved in well-labelled Eppendorf tubes containing silica gel. On each sampling day, previously sampled homes were not visited again to sample mosquitoes. For each sampling technique, houses were randomly selected at each site and GPS coordinates were recorded for all collection points. Morphological identification of Aedes mosquito species The different Aedes mosquito species that were sampled were identified morphologically using the identification keys of Huang et al 29 . The mosquito samples were further categorized based on sex. Aedes albopictus and Ae. aegypti were differentiated from other found Aedes mosquitoes by the following morphological characteristics; Ae. albopictus : its distinctive black and white striped pattern on the body and legs. The thorax (mid-section) has a prominent silver-white line down the middle; Ae. aegypti : distinctive black and white markings on their bodies, especially the lyre-shaped pattern on their thorax and white bands on their legs. Insecticide Susceptibility and Synergist Assays WHO tube bioassays were conducted to assess the phenotypic resistance of F 1 Aedes albopictus and Fo Aedes aegypti to 0.05% deltamethrin, 0.75% permethrin, and 0.25% pirimiphos-methyl, following WHO guidelines 31 . Mosquitoes (3–5 days old, non-blood-fed) were exposed for 60 minutes, with knockdown recorded every 10 minutes and mortality assessed after 24 hours. While the impregnated test papers used were designed for Anopheles mosquitoes, they remain widely used for Aedes susceptibility testing 32 . To evaluate the role of cytochrome P450 monooxygenases in resistance, PBO synergist assays were performed. Mosquitoes were pre-exposed to 4% PBO papers for 1 hour before being transferred to permethrin (0.75%) or deltamethrin (0.05%) for another hour. Knockdown was recorded during exposure, and mortality was assessed at 24 hours. These assays were conducted following WHO standards 31 . Resistant (alive) and susceptible (dead) Aedes mosquitoes were stored in silica gel for further morphological identification and molecular analysis. Genotyping of kdr mutations in Aedes albopictus and Aedes aegypti populations. A sub-sample of 103 adult Aedes mosquitoes and 181 phenotyped pyrethroid-resistant and susceptible Aedes mosquitoes were genotyped for kdr mutations, F1534C , V1016I and V410L . Total DNA was extracted from whole mosquitoes using the DNeasy Tissue Kit (Qiagen, In USA). Genotyping of the kdr mutations was done using allele-specific PCR according to the protocols of Linss et al. 33 and Villanueva-Segura et al . 34 . Data Management and Analysis Descriptive analysis was done to visualize WHO susceptibility data, resistant allele frequencies, and mosquito species composition from the selected sites using graphs and tables. WHO insecticide susceptibility levels were classified using the WHO criteria 35 , 36 . Allele frequencies of resistance gene markers in the vector populations at each site were calculated using Hardy-Weinberg equilibrium (HWE), with the formula F (allele frequency) = (2nRR + nRS) / 2N. Inferential statistics were applied to compare distributions across sites, seasons, and collection methods. Student’s t-tests were used to compare mean mosquito abundances between groups (e.g., dry vs. rainy season; indoor vs. outdoor), while Chi-square (ꭓ²) tests were applied to assess differences in species composition and insecticide susceptibility outcomes. Statistical significance was set at P ≤ 0.05. All statistical analyses were done in R 4.2.2 via RStudio (2022.12.0 + 353) and STATA/IC 14.1. Declarations Competing Interests The authors declared no conflict of interest. Ethics declarations This study was approved by the Ethics and Protocol Review Committee of the College of Health Sciences, University of Ghana (protocol identification number: CHS-Et/M.9-P4.3/2023–2024). All methods were carried out in accordance with relevant guidelines and regulations, including the ethical principles outlined in the Declaration of Helsinki for medical research. Meetings were held at each study site with chiefs, community leaders, and residents to introduce the research. Permission to conduct the study at the various sites was obtained from community leaders. Verbal informed consent was obtained from community leaders and residents for mosquito sampling activities. Consent to publish Not applicable Funding This study was supported by grants from the National Institute of Health (NIH grant nos. R03 A1186018 and D43 TW 011513). Author Contribution F.A.O., C.M.O.-A., A.O.F, I.A.B. and Y.A.A. were responsible for the study design, supervised the data collection, and contributed to the writing of the manuscript. F.A.O., C.M.O.-A. were responsible for data collection. F.A.O, C.M.O.-A, A.A and I.K.S. performed the laboratory work. C.M.O.-A and F.A.O. performed the data visualization and analysis. C.M.O.-A and F.A.O. were responsible for morphological identification of Aedes species. F.A.O., C.M.O.-and A., A.A. drafted the manuscript. All the authors read and approved the final manuscript. Acknowledgement We are grateful to the community members and field assistants for their support during sample collection and for granting permission to conduct the study within their localities. We also acknowledge the Port Health authorities at the Takoradi seaport for providing the necessary permits to carry out sampling within the port area. Data Availability The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request. References Weetman, D. et al. Aedes Mosquitoes and Aedes-Borne Arboviruses in Africa: Current and Future Threats. Int J. Environ. Res. Public. Health 15 (2018). Kamgang, B., Yougang, A. P., Tchoupo, M., Riveron, J. M. & Wondji, C. Temporal distribution and insecticide resistance profile of two major arbovirus vectors Aedes aegypti and Aedes albopictus in Yaoundé, the capital city of Cameroon. Parasit. Vectors . 10 , 469 (2017). Montgomery, M. et al. Spatial distribution of insecticide resistant populations of Aedes aegypti and Ae. albopictus and first detection of V410L mutation in Ae. aegypti from Cameroon. Infect. Dis. Poverty . 11 , 90 (2022). Ngoagouni, C., Kamgang, B., Nakouné, E., Paupy, C. & Kazanji, M. Invasion of Aedes albopictus (Diptera: Culicidae) into central Africa: what consequences for emerging diseases? Parasites Vectors . 8 , 191 (2015). Farooq, Z. et al. Impact of climate and Aedes albopictus establishment on dengue and chikungunya outbreaks in Europe: a time-to-event analysis. Lancet Planet. Health . 9 , e374–e383 (2025). Liu, H. et al. Climate change and Aedes albopictus risks in China: current impact and future projection. Infect. Dis. Poverty . 12 , 26 (2023). Baltar, J. M. C. et al. Gut Bacterial Diversity of Field and Laboratory-Reared Aedes albopictus Populations of Rio de Janeiro, Brazil. Viruses 15 (2023). Rezza, G. Aedes albopictus and the reemergence of Dengue. BMC Public. Health . 12 , 72 (2012). Longbottom, J. et al. Aedes albopictus invasion across Africa: the time is now for cross-country collaboration and control. Lancet Global Health . 11 , e623–e628 (2023). Waldock, J. et al. The role of environmental variables on Aedes albopictus biology and chikungunya epidemiology. Pathog Glob Health . 107 , 224–241 (2013). Mwanyika, G. O. et al. Dengue Virus Infection and Associated Risk Factors in Africa: A Systematic Review and Meta-Analysis. Viruses 13 (2021). Agboli, E. et al. Arbovirus Epidemiology: The Mystery of Unnoticed Epidemics in Ghana, West Africa. Microorganisms 10 (2022). Im, J. et al. The epidemiology of dengue outbreaks in 2016 and 2017 in Ouagadougou, Burkina Faso. Heliyon 6 , e04389 (2020). Amarasinghe, A., Kuritsk, J. N., Letson, G. W. & Margolis, H. S. Dengue virus infection in Africa. Emerg. Infect. Dis. 17 , 1349–1354 (2011). Suzuki, T. et al. Risk of transmission of viral haemorrhagic fevers and the insecticide susceptibilitystatus of aedes aegypti (linnaeus) in some sites in Accra, Ghana. Ghana. Med. J. 50 , 136–141 (2016). Akyea-Bobi, N. E. et al. Entomological risk assessment for transmission of arboviral diseases by Aedes mosquitoes in a domestic and forest site in Accra, Ghana. PLoS One . 18 , e0295390 (2023). Appiah, G. A., Babason, J. J., Dziworshie, A. Y., Abankwa, A. & Bonney, J. H. K. Is Ghana Prepared for Another Arboviral Outbreak? Evaluating the 2024 Dengue Fever Outbreak in the Context of Past Yellow Fever, Influenza, and COVID-19 Outbreaks. Trop. Med. Infect. Disease . 10 , 196 (2025). Konkon, A. K. et al. Insecticide resistance status of Aedes aegypti and Aedes albopictus mosquitoes in southern Benin, West Africa. Trop. Med. Health . 51 , 22 (2023). Kamgang, B. et al. Insecticide susceptibility of Aedes aegypti and Aedes albopictus in Central Africa. Parasit. Vectors . 4 , 79 (2011). WHO. Global vector control response 2017–2030. World Health Organisation (2017). Jeon, S. et al. Mosquito Surveillance at Airports and Seaports to Prevent and Control Emerging Mosquito-borne Diseases in Korea, 2023. Public. Health Wkly. Rep. 18 , 447–464 (2025). Tatem, A. J., Hay, S. I. & Rogers, D. J. Global traffic and disease vector dispersal. Proc. Natl. Acad. Sci. U S A . 103 , 6242–6247 (2006). Longbottom, J. et al. Aedes albopictus invasion across Africa: the time is now for cross-country collaboration and control. Lancet Global Health . 11 , e623–e628 (2023). Kamgang, B. et al. Geographical distribution of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) and genetic diversity of invading population of Ae. albopictus in the Republic of the Congo. Wellcome Open. Res. 3 , 79 (2018). Tedjou, A. N., Kamgang, B., Yougang, A. P., Njiokou, F. & Wondji, C. S. Update on the geographical distribution and prevalence of Aedes aegypti and Aedes albopictus (Diptera: Culicidae), two major arbovirus vectors in Cameroon. PLoS Negl. Trop. Dis. 13 , e0007137 (2019). Kamgang, B. et al. Temporal patterns of abundance of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) and mitochondrial DNA analysis of Ae. albopictus in the Central African Republic. PLoS Negl. Trop. Dis. 7 , e2590 (2013). Simard, F., Nchoutpouen, E., Toto, J. C. & Fontenille, D. Geographic distribution and breeding site preference of Aedes albopictus and Aedes aegypti (Diptera: culicidae) in Cameroon, Central Africa. J. Med. Entomol. 42 , 726–731 (2005). Abdulai, A. et al. Insecticide resistance status of Aedes aegypti in southern and northern Ghana. Parasites Vectors . 16 , 135 (2023). Huang, Y. M. The subgenus Stegomyia of Aedes in the Afrotropical Region with keys to the species (Diptera: Culicidae). Zootaxa 700 , 1–120 (2004). Smallegange, R. C. et al. Sugar-fermenting yeast as an organic source of carbon dioxide to attract the malaria mosquito Anopheles gambiae. Malar. J. 9 , 292 (2010). WHO. Standard operating procedure for testing insecticide susceptibility of adult mosquitoes in WHO tube tests. World Health Organisation , 16 (2022). Moyes, C. L. et al. Contemporary status of insecticide resistance in the major Aedes vectors of arboviruses infecting humans. PLoS Negl. Trop. Dis. 11 , e0005625 (2017). Linss, J. G. B. et al. Distribution and dissemination of the Val1016Ile and Phe1534Cys Kdr mutations in Aedes aegypti Brazilian natural populations. Parasites Vectors . 7 , 25 (2014). Villanueva-Segura, O. K. et al. Distribution and Frequency of the kdr Mutation V410L in Natural Populations of Aedes aegypti (L.) (Diptera: Culicidae) From Eastern and Southern Mexico. J. Med. Entomol. 57 , 218–223 (2020). WHO. Standard operating procedure for testing insecticide susceptibility of adult mosquitoes in WHO tube tests. World Health Organization , 16 (2022a). WHO. Standard operating procedure for testing insecticide susceptibility of adult mosquitoes in WHO bottle bioassays. World Health Organization , 21 (2022b). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7407322","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":512616171,"identity":"2c80c14c-8dc5-4ec6-bba0-6fc7767a101a","order_by":0,"name":"Faustina Adobea Owusu","email":"","orcid":"","institution":"University of Ghana","correspondingAuthor":false,"prefix":"","firstName":"Faustina","middleName":"Adobea","lastName":"Owusu","suffix":""},{"id":512616172,"identity":"1ba2f770-c5e6-4994-98cf-d5b070fd6ad3","order_by":1,"name":"Christopher Mfum Owusu-Asenso","email":"","orcid":"","institution":"University of Ghana","correspondingAuthor":false,"prefix":"","firstName":"Christopher","middleName":"Mfum","lastName":"Owusu-Asenso","suffix":""},{"id":512616173,"identity":"ea1cd35b-8cc8-46a4-94f1-b9cda1624b87","order_by":2,"name":"Anisa Abdulai","email":"","orcid":"","institution":"University of Ghana","correspondingAuthor":false,"prefix":"","firstName":"Anisa","middleName":"","lastName":"Abdulai","suffix":""},{"id":512616174,"identity":"98733411-0280-4106-945d-422c30bfbe2a","order_by":3,"name":"Isaac Kwame Sraku","email":"","orcid":"","institution":"University of Ghana","correspondingAuthor":false,"prefix":"","firstName":"Isaac","middleName":"Kwame","lastName":"Sraku","suffix":""},{"id":512616175,"identity":"a2180a7a-591e-4924-875c-acc1d38c4451","order_by":4,"name":"Akua Obeng Forson","email":"","orcid":"","institution":"University of Ghana School of Biomedical and Allied Health Sciences, University of Ghana","correspondingAuthor":false,"prefix":"","firstName":"Akua","middleName":"Obeng","lastName":"Forson","suffix":""},{"id":512616176,"identity":"617e3eb6-1813-4a76-a9e3-4820639eacf0","order_by":5,"name":"Isaac Anim-Baidoo","email":"","orcid":"","institution":"University of Ghana School of Biomedical and Allied Health Sciences, University of Ghana","correspondingAuthor":false,"prefix":"","firstName":"Isaac","middleName":"","lastName":"Anim-Baidoo","suffix":""},{"id":512616177,"identity":"e14be599-3d86-4f26-9142-fcd41cbf11ed","order_by":6,"name":"Yaw Asare Afrane","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAz0lEQVRIiWNgGAWjYFACxgcgUg7M5gFiA8JamMFqjEnXkthAtBaD44fZPvzcYZO+4fwCxgdv2xjsthPUciaZeWbvmbTcDTceMBvObWNI3tlASMuB/MMMvG2HgVoOsEnzArUYHCCk5fxjZsa/bf/TDW4cYP9NnJYbyczMvG0HEgzON7ABGQx2BLVI3njMzCzblmw48wZjs+SccxIJBLXwnU9mZnzbZifPd/7wwQ9vymzsCWpRgCuQAEcNhMQL5OEq+CGa7QnpGAWjYBSMgpEHAFKMRN4qcRbQAAAAAElFTkSuQmCC","orcid":"","institution":"University of Ghana Medical School","correspondingAuthor":true,"prefix":"","firstName":"Yaw","middleName":"Asare","lastName":"Afrane","suffix":""}],"badges":[],"createdAt":"2025-08-19 10:08:18","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7407322/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7407322/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":91078057,"identity":"62ccfee8-cbfe-4cdb-b509-2f2e713d17e3","added_by":"auto","created_at":"2025-09-11 11:17:32","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":816248,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMap of Western Region of Ghana, showing the study sites\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-7407322/v1/5221a1e71c822c844ee94d01.png"},{"id":91078054,"identity":"f603eab8-7ad0-44ea-92a1-5b60235742b8","added_by":"auto","created_at":"2025-09-11 11:17:32","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":42187,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003e\u003cstrong\u003eAedes\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e abundance per study site; a: seasonal abundance of Adult \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eAedes\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e Mosquitoes; b: resting location (indoor/outdoor)\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-7407322/v1/102105a7254dc480aebde34a.png"},{"id":91078056,"identity":"34d4dff2-1843-432c-a4d1-c80387aa73d1","added_by":"auto","created_at":"2025-09-11 11:17:32","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":33305,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSeasonal \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eAedes\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e Abundance per Trap type (BG-Biogents sentinel trap; HLC-Human Landing Catches; PPK-Prokopack aspiration)\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Fig3.png","url":"https://assets-eu.researchsquare.com/files/rs-7407322/v1/2d85d8be827eb95a00a8d1bb.png"},{"id":91078055,"identity":"6df872da-cc8e-4080-9308-c225c1c16ee7","added_by":"auto","created_at":"2025-09-11 11:17:32","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":67547,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePhenotypic Resistance profile of \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eAedes\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003eto Insecticides; a: WHO susceptibility bioassay for \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eAe. aegypti\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e and \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eAe. albopictus\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e; b: PBO synergist assay on \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eAe. aegypti\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-7407322/v1/c28280bfae55826da33afd0f.png"},{"id":106384767,"identity":"99b0954c-6bf1-4041-ac07-ed3902a41587","added_by":"auto","created_at":"2026-04-08 05:56:42","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2471237,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7407322/v1/a6369110-aac0-48f0-813a-a3698687a05a.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Invasion of the Dengue Vector Aedes albopictus in the Port City of Takoradi, Southwestern Ghana","fulltext":[{"header":"Background","content":"\u003cp\u003eOver the past few decades, \u003cem\u003eAedes albopictus\u003c/em\u003e, also known as the Asian tiger mosquito, has expanded its range from its native habitats in Southeast Asia to various regions across the world including Africa \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. Its invasion has been attributed to human-mediated activities such as the international trade of tyres \u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e and climate change \u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e, which provide ideal breeding habitats and enabling the species to establish and thrive in diverse ecological settings. The vector's adaptability to different climatic conditions, its ecological plasticity and ability to outcompete native mosquito species has facilitated its establishment across the African continent \u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003e\u003cem\u003eAedes albopictus\u003c/em\u003e is an efficient vector of dengue fever and has been implicated in the increased outbreak of dengue and other arboviral diseases in Africa \u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. In West Africa, where urbanization is accelerating, the rapid invasion and establishment of the dengue vector \u003cem\u003eAe. albopictus\u003c/em\u003e poses a significant risk of outbreak and sustained transmission of arboviral diseases, particularly in densely populated cities with limited vector control programs \u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. Recent reports suggest an alarming increase in dengue cases across the sub-Saharan region; Nigeria, C\u0026ocirc;te d'Ivoire, Burkina Faso and Togo \u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e. Ghana shares its geographical borders with these countries, signifying the growing threat posed by the disease. In Ghana, after the initial discovery of a single \u003cem\u003eAedes albopictus\u003c/em\u003e at the University of Ghana Legon campus \u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e, another study found \u003cem\u003eAedes albopictus\u003c/em\u003e larvae in Madina, Accra \u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e. However, till date, there is paucity of data on the ecology and insecticide resistance profiles of the \u003cem\u003eAedes albopictus\u003c/em\u003e in Ghana and their potential role in arboviral disease transmission.\u003c/p\u003e\u003cp\u003eInterestingly, in September 2023, an entomological surveillance focused on \u003cem\u003eAnopheles\u003c/em\u003e mosquitoes in Takoradi in the Western Region of Ghana led to the unexpected finding of the highly invasive vector \u003cem\u003eAedes albopictus\u003c/em\u003e in significant numbers in Apowa, a peri-urban area about 10 km away from the Takoradi port. This incidental finding may indicate the invasion and establishment of the dengue vector in the region, raising concerns about its potential role in dengue transmission. A few months later, the Ghana Health Service reported several outbreaks of dengue in Ghana for the first time in July 2024 \u003csup\u003e17\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eMoreover, studies in West and Central Africa, including C\u0026ocirc;te d'Ivoire, Benin, Cameroon and the Central African Republic have reported insecticide resistance in \u003cem\u003eAe. albopictus\u003c/em\u003e populations \u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e, signaling the potential for similar challenges in Ghana.\u003c/p\u003e\u003cp\u003eRecognizing the increasing threat posed by \u003cem\u003eAe. albopictus\u003c/em\u003e, the World Health Organization has emphasized the need for integrated vector surveillance and control strategies to mitigate its spread \u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. In alignment with these recommendations, this study provides baseline data into the vector\u0026rsquo;s population dynamics and insecticide resistance in Takoradi, Ghana.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eDistribution and abundance of\u003c/strong\u003e \u003cstrong\u003eAedes\u003c/strong\u003e \u003cstrong\u003eLarval Habitats.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDuring the study period, a total of 450 larval habitats with 50 positive breeding habitats for \u003cem\u003eAedes\u003c/em\u003e mosquitoes were identified across the study areas. The positive breeding habitats surveyed comprised of five (5) distinct habitat types, all of which were man-made. The most abundant habitat type was car tyres (62.0%) followed by discarded containers (16.0%), drums (8.0%), buckets (8.0%), and jerry cans (6.0%), (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). Relative to seasons, results obtained showed that more larval habitats were encountered in the rainy season (n\u0026thinsp;=\u0026thinsp;33, 66%) as compared to the dry season (n\u0026thinsp;=\u0026thinsp;17, 34%) (ꭓ\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e = 3.31, \u003cem\u003edf\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.5). All positive \u003cem\u003eAedes\u003c/em\u003e breeding habitats (n\u0026thinsp;=\u0026thinsp;50, 100.0%) encountered during the study period were located outdoors (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eDistribution and Abundance of Larval Habitats.\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eHabitat type\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"2\" align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n\u003cth colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eCount of habitat type\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eDry (%)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eRainy (%)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eTotal (%)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eBucket\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2 (50.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e2 (50.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4 (100.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eDiscarded container\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e3 (37.5)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e5 (62.5)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e8 (100.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eDrum\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2 (50.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e2 (50.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4 (100.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eJerry can\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2 (66.7)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e1 (33.3)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e3 (100.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eCar tyre\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e8 (25.8)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e23 (74.2)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e31 (100.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eTotal\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003e17 (34.0)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003e33 (66.0)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003e50 (100.0)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cstrong\u003eAbundance of\u003c/strong\u003e \u003cstrong\u003eAedes\u003c/strong\u003e \u003cstrong\u003eLarval in the Breeding Habitats\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA total of 2,666 \u003cem\u003eAede\u003c/em\u003es mosquito larvae were collected from the surveyed breeding habitats. The most productive habitat was car tyres 66.4% (1,771) (\u003cem\u003eF\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.06, \u003cem\u003edf\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.50) (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). A relatively high abundance of \u003cem\u003eAedes\u003c/em\u003e immatures were sampled during the rainy season, 65.8% (1,755), whereas 34.2% (911) were collected during the dry season (\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.04, \u003cem\u003edf\u003c/em\u003e\u0026thinsp;=\u0026thinsp;48, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.96). The highest larval abundance was recorded in Apowa across both seasons (n\u0026thinsp;=\u0026thinsp;2,184, 81.9%) (\u003cem\u003eF\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2.36, \u003cem\u003edf\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.50), (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003ctable id=\"Tab2\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eThe seasonal distribution of \u003cem\u003eAedes\u003c/em\u003e larvae across the study sites.\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eContainer type\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eApowa\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eTakoradi Port\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eDry (%)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eRainy (%)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eDry (%)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eRainy (%)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eDrum\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e97 (10.6)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e173 (13.6)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0 (0.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0 (0.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eDiscarded container\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e145 (15.9)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e144 (11.3)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0 (0.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e103 21.4)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eJerry can\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e70 (7.7)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e72 (5.7)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0 (0.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0 (0.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eCar tyre\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e583 (64.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e809 (63.6)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0 (0.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e379 (78.6)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eBucket\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e16 (1.8)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e75 (5.9)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0 (0.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0 (0.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eTotal\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003e911 (100.0)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003e1,273 (100.0)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003e0 (0.0)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003e482 (100.0)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eLarval samples collected from the study areas, which emerged into adult \u003cem\u003eAedes\u003c/em\u003e mosquitoes were morphologically identified as \u003cem\u003eAedes aegypti\u003c/em\u003e (97.3%) and \u003cem\u003eAedes albopictus\u003c/em\u003e (2.3%), (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). \u003cem\u003eAedes aegypti\u003c/em\u003e larvae were collected from both study areas, while \u003cem\u003eAedes albopictus\u003c/em\u003e larvae were specifically obtained from car tires in the Takoradi Port and its surrounding areas (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003ctable id=\"Tab3\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eMorphological Identification of Emerged \u003cem\u003eAedes\u003c/em\u003e Mosquitoes\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eStudy sites\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eAe. aegypti\u003c/em\u003e (%)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eAe. albopictus\u003c/em\u003e (%)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eTotal (%)\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eApowa\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e460 (100.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0 (0.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e460 (100.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eTakoradi Port\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e250 (92.6)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e20 (7.4)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e270 (100.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eTotal\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003e710 (97.3)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003e20 (2.7)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003e730 (100.0)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cstrong\u003eAdult\u003c/strong\u003e \u003cstrong\u003eAedes\u003c/strong\u003e \u003cstrong\u003emosquito distribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA total of 1,268 mosquitoes belonging to three different genera were sampled during the study; \u003cem\u003eAedes\u003c/em\u003e (n\u0026thinsp;=\u0026thinsp;960, %), \u003cem\u003eCulex\u003c/em\u003e (n\u0026thinsp;=\u0026thinsp;288, %) and \u003cem\u003eAnopheles\u003c/em\u003e (n\u0026thinsp;=\u0026thinsp;3, %). Out of the total 960 adult \u003cem\u003eAedes\u003c/em\u003e mosquitoes sampled during the study, \u003cem\u003eAedes aegypti\u003c/em\u003e (n\u0026thinsp;=\u0026thinsp;837; 87.2%) was the most predominant species by morphological identification, this was followed by \u003cem\u003eAedes albopictus\u003c/em\u003e (n\u0026thinsp;=\u0026thinsp;117; 12.2%) and then \u003cem\u003eAedes chemulpoensis\u003c/em\u003e (n\u0026thinsp;=\u0026thinsp;6; 0.6%). Site-specific species distribution showed that, a high abundance of \u003cem\u003eAedes\u003c/em\u003e mosquitoes were sampled in Apowa (n\u0026thinsp;=\u0026thinsp;443; 46.1%) [\u003cem\u003eAedes aegypti\u003c/em\u003e (n\u0026thinsp;=\u0026thinsp;371; 83.7%), \u003cem\u003eAedes albopictus\u003c/em\u003e (n\u0026thinsp;=\u0026thinsp;66; 14.9%), \u003cem\u003eAedes chemulpoensis\u003c/em\u003e (n\u0026thinsp;=\u0026thinsp;6; 1.4%)] (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003ctable id=\"Tab4\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eMorphological Identification of Adult \u003cem\u003eAedes\u003c/em\u003e Abundance\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eStudy sites\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eAe. aegypti\u003c/em\u003e (%)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eAe. albopictus\u003c/em\u003e (%)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eAe. chemulpoensis\u003c/em\u003e (%)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eTotal (%)\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eApowa\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e371 (83.7)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e66 (14.9)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6 (1.4)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e443 (100.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eTakoradi Port\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e352 (87.3)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e51 (12.7)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0 (0.00)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e403 (100.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eAnaji\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e114 (100.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0 (0.00)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0 (0.00)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e114 (100)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eTotal\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003e837 (87.2)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003e117 (12.2)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003e6 (0.6)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003e960 (100)\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eSignificantly higher numbers of \u003cem\u003eAedes\u003c/em\u003e mosquitoes we sampled during the rainy season (n\u0026thinsp;=\u0026thinsp;730; 76.0%) [Takoradi Port (n\u0026thinsp;=\u0026thinsp;354; 48.5%), Apowa (n\u0026thinsp;=\u0026thinsp;262; 35.9%), Anaji (n\u0026thinsp;=\u0026thinsp;114; 15.6%)] (Fig.\u0026nbsp;2a) compared to the dry season n\u0026thinsp;=\u0026thinsp;230; 24.0%) [Apowa (n\u0026thinsp;=\u0026thinsp;181; 78.7%), Takoradi Port (n\u0026thinsp;=\u0026thinsp;49; 21.3%), Anaji (n\u0026thinsp;=\u0026thinsp;0; 0%)], (\u003cem\u003et\u003c/em\u003e = -2.29, \u003cem\u003edf\u003c/em\u003e\u0026thinsp;=\u0026thinsp;275, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.011). Significantly high abundance of \u003cem\u003eAedes\u003c/em\u003e mosquitoes were collected outdoors (n\u0026thinsp;=\u0026thinsp;909; 94.7%) as compared to indoor collection 51 (5.3%), (\u003cem\u003et\u003c/em\u003e = -5.31, \u003cem\u003edf\u003c/em\u003e\u0026thinsp;=\u0026thinsp;275, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0,001). Apowa recorded the highest indoor collections (n\u0026thinsp;=\u0026thinsp;47; 92.6%), while most mosquitoes collected outdoor were from Takoradi Port (n\u0026thinsp;=\u0026thinsp;399; 41.6%) (Fig.\u0026nbsp;2b).\u003c/p\u003e\n\u003cp\u003eA high abundance (n\u0026thinsp;=\u0026thinsp;923) of host-seeking \u003cem\u003eAedes\u003c/em\u003e mosquitoes (mosquitoes sampled using HLC\u0026thinsp;+\u0026thinsp;BG traps) were sampled over the entire sampling period, with a high abundance (n\u0026thinsp;=\u0026thinsp;858) of actively biting (mosquitoes collected using HLC) \u003cem\u003eAedes\u003c/em\u003e mosquitoes (\u003cem\u003eF\u003c/em\u003e\u0026thinsp;=\u0026thinsp;26.55, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). (Fig.\u0026nbsp;3). Overall, a total of 37 resting mosquitoes were collected using PPK aspirators (Fig.\u0026nbsp;3).\u003c/p\u003e\n\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n\u003ch2\u003eInsecticide Susceptibility and Synergist Assays\u003c/h2\u003e\n\u003cp\u003ePhenotypic resistance results showed that the \u003cem\u003eAedes albopictus\u003c/em\u003e mosquito population was susceptible to Deltamethrin (Mortality rate (MR)\u0026thinsp;=\u0026thinsp;98.8%), Permethrin (MR\u0026thinsp;=\u0026thinsp;100.0%), and Pirimiphos-methyl (100.0%). In comparison, the \u003cem\u003eAedes aegypti\u003c/em\u003e population showed resistance to pyrethroids (Permethrin (74.3%); Deltamethrin (MR\u0026thinsp;=\u0026thinsp;75.0%)) and full susceptibility to Pirimiphos-methyl (MR\u0026thinsp;=\u0026thinsp;100.0%) (ꭓ\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e = 230, \u003cem\u003edf\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u0026lt;\u0026thinsp;0.001) (Fig.\u0026nbsp;4a). However, preexposure of \u003cem\u003eAedes aegypti\u003c/em\u003e mosquito to PBO before the bioassay, restored full susceptibility of the mosquito population to pyrethroids (ꭓ\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e = 79, \u003cem\u003edf\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u0026lt;\u0026thinsp;0.001) (Fig.\u0026nbsp;4b).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eGenotypic Resistance of\u003c/strong\u003e \u003cstrong\u003eAedes\u003c/strong\u003e \u003cstrong\u003emosquitoes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA sub-sample of 103 field-caught \u003cem\u003eAedes\u003c/em\u003e mosquitoes [\u003cem\u003eAe. albopictus\u003c/em\u003e\u0026thinsp;=\u0026thinsp;53; \u003cem\u003eAe. aegypti\u003c/em\u003e\u0026thinsp;=\u0026thinsp;50] were randomly selected and subjected to allele-specific PCR to detect the presence of \u003cem\u003ekdr\u003c/em\u003e mutations \u003cem\u003eF1534C\u003c/em\u003e, \u003cem\u003eV1016I\u003c/em\u003e and \u003cem\u003eV410L\u003c/em\u003e. Low allelic frequencies of \u003cem\u003eF1534C\u003c/em\u003e (F\u0026thinsp;=\u0026thinsp;0.18) (ꭓ\u003csup\u003e2\u003c/sup\u003e = 16.09, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), \u003cem\u003eV410L\u003c/em\u003e (F\u0026thinsp;=\u0026thinsp;0.02) (ꭓ\u003csup\u003e2\u003c/sup\u003e = 0.02, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.89) and \u003cem\u003eV1016I\u003c/em\u003e (F\u0026thinsp;=\u0026thinsp;0.00) were detected in \u003cem\u003eAe\u003c/em\u003e. \u003cem\u003ealbopictus\u003c/em\u003e. However, high allelic frequency (F\u0026thinsp;=\u0026thinsp;0.66) of \u003cem\u003eF1534C\u003c/em\u003e (ꭓ\u003csup\u003e2\u003c/sup\u003e = 1.26, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.26) and \u003cem\u003eV1016I\u003c/em\u003e (F\u0026thinsp;=\u0026thinsp;0.50) (ꭓ\u003csup\u003e2\u003c/sup\u003e = 50, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and a much lower allelic frequency (F\u0026thinsp;=\u0026thinsp;0.06) of \u003cem\u003eV410L\u003c/em\u003e (ꭓ\u003csup\u003e2\u003c/sup\u003e = 0.20, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.65) mutations was observed in \u003cem\u003eAe. aegypti\u003c/em\u003e (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u0026nbsp;\u003c/div\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003ctable id=\"Tab5\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eNumber of genotypes and frequencies of the \u003cem\u003eV1016I\u003c/em\u003e, \u003cem\u003eF1534C\u003c/em\u003e and \u003cem\u003eV410L\u003c/em\u003e mutations in the voltage-gated sodium channel gene of adult \u003cem\u003eAedes aegypti\u003c/em\u003e and \u003cem\u003eAedes albopictus\u003c/em\u003e mosquitoes.\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eN\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eF1534C\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n\u003cth colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eV410L\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n\u003cth colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eV1016I\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eSpecies\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eCC\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eFF\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eFC\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eF\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eLL\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eVV\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eVL\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eF\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eII\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eVV\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eVI\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eF\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eAedes albopictus\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e53\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e40\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e7\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.18\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e51\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.02\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e53\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.00\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eAedes aegypti\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e50\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e20\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e26\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.66\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e44\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.06\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e50\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.50\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eTotal\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e103\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e26\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e44\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e33\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e95\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e8\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e53\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e50\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003ch3\u003e(CC, II, LL-Kdr; FF, VV-wild-type; FC, VI, VL-Heterozygote, F; Allelic frequency, N; number)\u003c/h3\u003e\n\u003cp\u003eGenotypic analysis of \u003cem\u003eAedes albopictus\u003c/em\u003e and \u003cem\u003eAedes aegypti\u003c/em\u003e mosquitoes from bioassays revealed relatively high frequencies of \u003cem\u003eF1534C\u003c/em\u003e (Allelic frequency (F)\u0026thinsp;=\u0026thinsp;0.75) and \u003cem\u003eV1016I\u003c/em\u003e (F\u0026thinsp;=\u0026thinsp;0.50) in deltamethrin-susceptible \u003cem\u003eAe. albopictus\u003c/em\u003e mosquitoes, while all three \u003cem\u003ekdr\u003c/em\u003e mutations (\u003cem\u003eF1534C\u003c/em\u003e, \u003cem\u003eV1016I\u003c/em\u003e, and \u003cem\u003eV410L\u003c/em\u003e) were present at relatively high frequencies in deltamethrin-resistant \u003cem\u003eAe. albopictus\u003c/em\u003e mosquitoes (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e). Similarly, a high frequency of \u003cem\u003eF1534C\u003c/em\u003e (F\u0026thinsp;=\u0026thinsp;0.70) was detected in deltamethrin-susceptible \u003cem\u003eAe. aegypti\u003c/em\u003e mosquitoes, with moderate to low frequencies of \u003cem\u003eV1016I\u003c/em\u003e (F\u0026thinsp;=\u0026thinsp;0.40) and \u003cem\u003eV410L\u003c/em\u003e (F\u0026thinsp;=\u0026thinsp;0.15) respectively. Deltamethrin-resistant \u003cem\u003eAe. aegypti\u003c/em\u003e haboured relatively high frequencies of \u003cem\u003eF1534C\u003c/em\u003e (F\u0026thinsp;=\u0026thinsp;0.68) and \u003cem\u003eV1016I\u003c/em\u003e (F\u0026thinsp;=\u0026thinsp;0.50), with low frequency of \u003cem\u003eV410L\u003c/em\u003e (F\u0026thinsp;=\u0026thinsp;0.25). For permethrin-susceptible \u003cem\u003eAe. albopictus\u003c/em\u003e, relatively high to low levels of \u003cem\u003eV1016I\u003c/em\u003e (F\u0026thinsp;=\u0026thinsp;0.50) and \u003cem\u003eF1534C\u003c/em\u003e (F\u0026thinsp;=\u0026thinsp;0.25) was observed respectively. No \u003cem\u003eV410L\u003c/em\u003e mutation was detected. In contrast, \u003cem\u003eAe. aegypti\u003c/em\u003e mosquitoes exhibited higher frequencies of all three \u003cem\u003ekdr\u003c/em\u003e mutations in permethrin-susceptible and resistant populations (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003ctable id=\"Tab6\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eAllelic frequencies of the V1016I, F1534C and V410L mutations in the voltage-gated sodium channel gene of \u003cem\u003eAedes aegypti\u003c/em\u003e and \u003cem\u003eAedes albopictus\u003c/em\u003e mosquitoes from WHO Bioassays.\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eInsecticide\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eSpecies\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n\u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n\u003cth colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003eResistant genes (F)\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003ePhenotype\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eF1534C\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eV410L\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eV1016I\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"4\" align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eDeltamethrin\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eAe. albopictus\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eS\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e30\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.75\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.03\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.50\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eR\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.50\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.50\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.50\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eAe. aegypti\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eS\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e30\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.70\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.15\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.40\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eR\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e30\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.68\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.25\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.50\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"4\" align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003ePermethrin\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eAe. albopictus\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eS\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e30\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.25\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.00\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.50\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eR\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003eAe. aegypti\u003c/em\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eS\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e30\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.82\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.73\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.50\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eR\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e30\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.87\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.60\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.50\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e(S; Susceptible, R; Resistant, N; number, F; Allelic frequency)\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eDue to its highly invasive nature and capability of transmitting several globally important arboviruses such as Dengue, Chikungunya, Yellow fever and Zika, the invasion of \u003cem\u003eAedes albopictus\u003c/em\u003e in Ghana poses a significant public health threat. This study showed the detection of a significant number of \u003cem\u003eAe. albopictus\u003c/em\u003e in Takoradi, and its environs implying an invasion event that may be ongoing. The invasive vector however, showed susceptibility to insecticides that could be used for its control. This study provides baseline data crucial for public health action on invasive \u003cem\u003eAe. Albopictus\u003c/em\u003e that could be crucially involved in the transmission of arboviral disease in Ghana.\u003c/p\u003e\u003cp\u003eThe detection of the highly invasive species, \u003cem\u003eAedes albopictus\u003c/em\u003e in significant numbers in Takoradi, in the port, its environs and outside of the city represents a critical entomological finding with substantial implications for arboviral disease transmission in Ghana. Ports are well-documented entry points for invasive mosquito species \u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e. The global movement of goods, via maritime transport, has been linked to the transcontinental spread of \u003cem\u003eAe. albopictus\u003c/em\u003e through used car tyres \u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. It was shown in the current study that this invasive vector is breeding more in car tires. This invasive species could spread to other parts of Ghana through transport routes that are linked to the port. Given the species\u0026rsquo; known vector competence for dengue, chikungunya, yellow fever, and Zika viruses \u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e, its establishment in Ghana poses a significant public health concern.\u003c/p\u003e\u003cp\u003eThe emergence of \u003cem\u003eAedes albopictus\u003c/em\u003e across multiple study sites in Ghana coincided with reports of confirmed dengue outbreaks in several places in the country, including Southwestern Ghana by the Ghana Health Service \u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. While our current data do not establish a transmission link, the temporal overlap between the emergence of this invasive species and the surge in dengue cases raises critical questions. There is a big gap to ascertain potential involvement of \u003cem\u003eAe. albopictus\u003c/em\u003e in ongoing dengue transmission outbreaks. Understanding the role and extent to which this species contributes to dengue transmission is essential.\u003c/p\u003e\u003cp\u003eWhile \u003cem\u003eAe. aegypti\u003c/em\u003e remains the dominant urban vector, the introduction of \u003cem\u003eAe. albopictus\u003c/em\u003e, a competent dengue vector, could alter transmission dynamics. Its behavioral plasticity, ecological shift of the previously sylvatic vector into urban areas, and ability to exploit diverse breeding habitats enhance its adaptability and survival in diverse environments, potentially increasing its role in arboviral transmission dynamics. These traits not only allow \u003cem\u003eAe. albopictus\u003c/em\u003e to thrive under varying ecological pressures but also position it to potentially displace native \u003cem\u003eAe. aegypti\u003c/em\u003e populations. A similar trend has been reported in the Republic of Congo, where \u003cem\u003eAe. albopictus\u003c/em\u003e has overtaken \u003cem\u003eAe. aegypti\u003c/em\u003e as the dominant urban vector \u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e. Such displacement, coupled with the co-circulation of multiple \u003cem\u003eAedes\u003c/em\u003e species, may intensify arboviral transmission risks and complicate control strategies in endemic settings\u003c/p\u003e\u003cp\u003eThe WHO bioassays revealed full susceptibility of \u003cem\u003eAe. albopictus\u003c/em\u003e to pyrethroids and organophosphates. The susceptibility of these vectors may imply that insecticide-based control strategies could still yield high operational efficacy against this emerging vector, particularly in areas where it is newly established. This observation may suggest a critical advantage for effective vector control before the development and spread of resistance and establishment and expansion of \u003cem\u003eAe. albopictus\u003c/em\u003e populations. This finding was consistent with another study from\u003c/p\u003e\u003cp\u003eBenin \u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e. The low phenotypic resistance observed may be attributable to the species\u0026rsquo; relatively minimal prior exposure to insecticides and recent urban establishment. Contrary to the finding reported for \u003cem\u003eAe. albopictus\u003c/em\u003e, \u003cem\u003eAe. aegypti\u003c/em\u003e populations were resistant to pyrethroids, with full susceptibility restored after pre-exposure to PBO, suggesting metabolic resistance mechanisms may be involved. This is consistent with prior reports in Ghana, where pre-expose of pyrethroid resistant \u003cem\u003eAedes aegypti\u003c/em\u003e to PBO, restored susceptibility \u003csup\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study is the first to provides a baseline assessment of the invasion of \u003cem\u003eAe. albopictus\u003c/em\u003e and its insecticide resistance status in Ghana, and highlights the significant risk posed by this vector in arboviral disease transmission. Enhanced entomological and molecular surveillance is needed at major ports of entry and high-risk urban centers in Ghana to ascertain their involvement in the ongoing dengue transmission in Ghana, as well as the extent of the invasion.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003eStudy sites\u003c/h2\u003e\u003cp\u003eThis study was conducted in three (3) localities Southwestern part of Ghana; Apowa (4\u0026deg;53\u0026rsquo;0\u0026rdquo; N, 1\u0026deg;49\u0026rsquo;0\u0026rdquo; W), Anaji (4\u0026deg;54'16'' N, 2\u0026deg;6'51\u0026rdquo; W), and the Takoradi Port and surrounding areas (4\u0026deg;54'00'' N, 1\u0026deg;44'00'' W) to investigate the distribution, behavior, and insecticide resistance profiles of \u003cem\u003eAedes albopictus\u003c/em\u003e. Apowa where \u003cem\u003eAe. albopictus\u003c/em\u003e was first found accidentally in significant numbers became a focal site, while Anaji and the Takoradi port and its surrounding areas were selected to assess potential spread and introduction points of this invasive species (Fig.\u0026nbsp;1). The sea port at Takoradi receives all sorts of shipment including cars, car tyres, car spare parts, from all over the world. This may pose a substantial risk of introducing and establishing the \u003cem\u003eAe. albopictus\u003c/em\u003e and other invasive species into the port and its surrounding areas, which may increase the potential for arboviral transmission. The extensive transportation networks linking Takoradi to other regions of Ghana could facilitate the rapid spread of \u003cem\u003eAe. albopictus\u003c/em\u003e and its associated pathogens.\u003c/p\u003e\u003cp\u003eThe accidental detection of \u003cem\u003eAe. albopictus\u003c/em\u003e was in Apowa, and was selected as a study site following the citing of a significant abundance of \u003cem\u003eAe. albopictus\u003c/em\u003e within this area. Apowa, a peri-urban area in the Ahanta West Municipal District is situated about 10 km away from the Takoradi port and 6 km from Anaji.\u003c/p\u003e\u003cp\u003eAnaji is a residential suburb situated within the Sekondi‑Takoradi metropolitan area. Anaji lies approximately 4 km west of central Takoradi, the regional capital. Anaji is about 8 km north-west to the Takoradi port. The site was selected to ascertain the spread of the dengue vector away from the port and Apowa. Vector sampling in Anaji was done only in the rainy season due to logistics reason. From each of these sites with the exception of Anaji, both larval and adult collections were conducted during the rainy and dry seasons from September 2023 to February 2024. However, only the surrounding areas of the Takoradi port was sampled during the dry season, since the team was not able to acquire clearance to enter the port premises. After receiving clearance and collaborations with the Takoradi Port Health, the area within and around the port were sampled during the rainy season.\u003c/p\u003e\u003cp\u003eWith an average annual temperature of 26.5\u0026deg;C and a mean yearly rainfall of 787 mm, the selected study areas which are located in the coastal savannah region of Southwestern Ghana, has a tropical savannah weather pattern. The region has a bimodal rainfall pattern, with the long rainy season occurring from April to June and the minor one from October to November.\u003c/p\u003e\u003cp\u003eThis study was approved by the Ethics and Protocol Review Committee of the College of Health Sciences, University of Ghana (protocol identification number: CHS-Et/M.9-P4.3/2023\u0026ndash;2024). All methods were carried out in accordance with relevant guidelines and regulations, including the ethical principles outlined in the Declaration of Helsinki for medical research. Meetings were held at each study site with chiefs, community leaders, and residents to introduce the research. Permission to conduct the study at the various sites was obtained from community leaders. Verbal informed consent was obtained from community leaders and residents for mosquito sampling activities.\u003c/p\u003e\u003cp\u003e\u003cb\u003eMosquito sampling and characterization of\u003c/b\u003e \u003cb\u003eAedes\u003c/b\u003e \u003cb\u003ebreeding habitats\u003c/b\u003e\u003c/p\u003e\u003cp\u003eExtensive larval surveys were conducted from September 2023 to February 2024 in these study sites to locate water-holding containers (e.g., tyres, jerry cans, drums) in and around human habitations and inspected for \u003cem\u003eAedes\u003c/em\u003e immatures. The habitat type, its location within a household (whether indoor or outdoor) was recorded. All potential \u003cem\u003eAedes\u003c/em\u003e breeding containers were examined for the presence of \u003cem\u003eAedes\u003c/em\u003e immature and recorded in each site. Using pipettes and ladles, immature stages (field generation, Fo) were collected from containers positive for \u003cem\u003eAedes\u003c/em\u003e mosquitoes including vehicle tyres, drums, jerry cans, tanks, buckets and abandoned containers. For each sampling site, \u003cem\u003eAedes\u003c/em\u003e immatures were pooled in plastic larval bowls and transferred to the insectary at the Department of Medical Microbiology, University of Ghana. Larvae obtained were fed with TetraMin Baby fish food (Tetra Werke, Melle, Germany) throughout their development.\u003c/p\u003e\u003cp\u003eUpon emergence into adults, they were morphologically identified using standard taxonomic keys \u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. Once identified as \u003cem\u003eAe. aegypti\u003c/em\u003e or \u003cem\u003eAe. albopictus\u003c/em\u003e, mosquitoes of the same species and from the same locality were pooled into separate individual cages. Due to their low abundance, \u003cem\u003eAe. albopictus\u003c/em\u003e mosquitoes were reared to their first filial generation (F\u003csub\u003e1\u003c/sub\u003e) for adult bioassays. At the insectary, mosquito populations were maintained under controlled environmental conditions (relative humidity: 80\u0026thinsp;\u0026plusmn;\u0026thinsp;10%, temperature: 27\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C) and females were fed on rabbits to complete their gonotrophic cycle. The geographic coordinates of all sampling sites were documented with a geographical position system (GPSMAP\u0026reg; 60CSx).\u003c/p\u003e\u003cp\u003e\u003cb\u003eAdult\u003c/b\u003e \u003cb\u003eAedes\u003c/b\u003e \u003cb\u003emosquito collections\u003c/b\u003e\u003c/p\u003e\u003cp\u003eTo determine the spatial distribution and vector behaviour of adult \u003cem\u003eAedes\u003c/em\u003e mosquitoes, sampling was conducted indoors and outdoors of houses at each site using three sampling techniques; the BG-Sentinel 2 traps (BG trap) (Biogents AG, Weissenburgstr 22, 93055 Regensburg, Germany), Human landing catches (HLC) and Prokopack Aspirators (PPK) (John W. Hock Company, Gainesville, U.S.A.). At each study site, from the hours of 4:00 pm to 7:00 pm, the BG traps were positioned indoors (in bedrooms and living rooms) and outdoors (on open verandas, or under sheds/ trees where people gather, approximately 5 meters from the home). The traps were baited with CO\u003csub\u003e2\u003c/sub\u003e, which was a mixture made by adding 17.5 g of yeast (Angel Yeast (Egypt) Co. Ltd.) and 250 g of sugar to 1 liter of water \u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eFor the HLC sampling technique, trained volunteers acted as both baits and catchers. Four trained volunteers (two stationed indoors and two others outdoors) collected host-seeking \u003cem\u003eAedes\u003c/em\u003e mosquitoes daily between the hours 4:00pm to 7:00pm. Prokopack aspiration was employed to mechanically aspirate indoor and outdoor resting \u003cem\u003eAedes\u003c/em\u003e mosquitoes. The \u003cem\u003eAedes\u003c/em\u003e mosquitoes collected were stored in clearly labelled paper cups after which they were transported to the insectary for identification and molecular analysis. Collected \u003cem\u003eAedes\u003c/em\u003e mosquitoes were knocked down with chloroform and preserved in well-labelled Eppendorf tubes containing silica gel. On each sampling day, previously sampled homes were not visited again to sample mosquitoes. For each sampling technique, houses were randomly selected at each site and GPS coordinates were recorded for all collection points.\u003c/p\u003e\u003cp\u003e\u003cb\u003eMorphological identification of\u003c/b\u003e \u003cb\u003eAedes\u003c/b\u003e \u003cb\u003emosquito species\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe different \u003cem\u003eAedes\u003c/em\u003e mosquito species that were sampled were identified morphologically using the identification keys of Huang \u003cem\u003eet al\u003c/em\u003e \u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. The mosquito samples were further categorized based on sex. \u003cem\u003eAedes albopictus\u003c/em\u003e and \u003cem\u003eAe. aegypti\u003c/em\u003e were differentiated from other found \u003cem\u003eAedes\u003c/em\u003e mosquitoes by the following morphological characteristics; \u003cem\u003eAe. albopictus\u003c/em\u003e: its distinctive black and white striped pattern on the body and legs. The thorax (mid-section) has a prominent silver-white line down the middle; \u003cem\u003eAe. aegypti\u003c/em\u003e: distinctive black and white markings on their bodies, especially the lyre-shaped pattern on their thorax and white bands on their legs.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eInsecticide Susceptibility and Synergist Assays\u003c/h3\u003e\n\u003cp\u003eWHO tube bioassays were conducted to assess the phenotypic resistance of F\u003csub\u003e1\u003c/sub\u003e \u003cem\u003eAedes albopictus\u003c/em\u003e and Fo \u003cem\u003eAedes aegypti\u003c/em\u003e to 0.05% deltamethrin, 0.75% permethrin, and 0.25% pirimiphos-methyl, following WHO guidelines \u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e. Mosquitoes (3\u0026ndash;5 days old, non-blood-fed) were exposed for 60 minutes, with knockdown recorded every 10 minutes and mortality assessed after 24 hours. While the impregnated test papers used were designed for \u003cem\u003eAnopheles\u003c/em\u003e mosquitoes, they remain widely used for \u003cem\u003eAedes\u003c/em\u003e susceptibility testing \u003csup\u003e\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eTo evaluate the role of cytochrome P450 monooxygenases in resistance, PBO synergist assays were performed. Mosquitoes were pre-exposed to 4% PBO papers for 1 hour before being transferred to permethrin (0.75%) or deltamethrin (0.05%) for another hour. Knockdown was recorded during exposure, and mortality was assessed at 24 hours. These assays were conducted following WHO standards \u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e. Resistant (alive) and susceptible (dead) \u003cem\u003eAedes\u003c/em\u003e mosquitoes were stored in silica gel for further morphological identification and molecular analysis.\u003c/p\u003e\u003cp\u003e\u003cb\u003eGenotyping of\u003c/b\u003e \u003cb\u003ekdr\u003c/b\u003e \u003cb\u003emutations in\u003c/b\u003e \u003cb\u003eAedes albopictus\u003c/b\u003e \u003cb\u003eand\u003c/b\u003e \u003cb\u003eAedes aegypti\u003c/b\u003e \u003cb\u003epopulations.\u003c/b\u003e\u003c/p\u003e\u003cp\u003eA sub-sample of 103 adult \u003cem\u003eAedes\u003c/em\u003e mosquitoes and 181 phenotyped pyrethroid-resistant and susceptible \u003cem\u003eAedes\u003c/em\u003e mosquitoes were genotyped for \u003cem\u003ekdr\u003c/em\u003e mutations, \u003cem\u003eF1534C\u003c/em\u003e, \u003cem\u003eV1016I\u003c/em\u003e and \u003cem\u003eV410L\u003c/em\u003e. Total DNA was extracted from whole mosquitoes using the DNeasy Tissue Kit (Qiagen, In USA). Genotyping of the \u003cem\u003ekdr\u003c/em\u003e mutations was done using allele-specific PCR according to the protocols of Linss \u003cem\u003eet al.\u003c/em\u003e \u003csup\u003e\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e and Villanueva-Segura \u003cem\u003eet al\u003c/em\u003e.\u003csup\u003e\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eData Management and Analysis\u003c/h2\u003e\u003cp\u003eDescriptive analysis was done to visualize WHO susceptibility data, resistant allele frequencies, and mosquito species composition from the selected sites using graphs and tables.\u003c/p\u003e\u003cp\u003eWHO insecticide susceptibility levels were classified using the WHO criteria \u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e. Allele frequencies of resistance gene markers in the vector populations at each site were calculated using Hardy-Weinberg equilibrium (HWE), with the formula F (allele frequency) = (2nRR\u0026thinsp;+\u0026thinsp;nRS) / 2N.\u003c/p\u003e\u003cp\u003eInferential statistics were applied to compare distributions across sites, seasons, and collection methods. Student\u0026rsquo;s t-tests were used to compare mean mosquito abundances between groups (e.g., dry vs. rainy season; indoor vs. outdoor), while Chi-square (ꭓ\u0026sup2;) tests were applied to assess differences in species composition and insecticide susceptibility outcomes. Statistical significance was set at \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026le;\u0026thinsp;0.05. All statistical analyses were done in R 4.2.2 via RStudio (2022.12.0\u0026thinsp;+\u0026thinsp;353) and STATA/IC 14.1.\u003c/p\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003ch2\u003eCompeting Interests\u003c/h2\u003e\u003cp\u003eThe authors declared no conflict of interest.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003ch2\u003eEthics declarations\u003c/h2\u003e\u003cp\u003eThis study was approved by the Ethics and Protocol Review Committee of the College of Health Sciences, University of Ghana (protocol identification number: CHS-Et/M.9-P4.3/2023\u0026ndash;2024). All methods were carried out in accordance with relevant guidelines and regulations, including the ethical principles outlined in the Declaration of Helsinki for medical research. Meetings were held at each study site with chiefs, community leaders, and residents to introduce the research. Permission to conduct the study at the various sites was obtained from community leaders. Verbal informed consent was obtained from community leaders and residents for mosquito sampling activities.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003ch2\u003eConsent to publish\u003c/h2\u003e\u003cp\u003eNot applicable\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e\u003cp\u003eThis study was supported by grants from the National Institute of Health (NIH grant nos. R03 A1186018 and D43 TW 011513).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eF.A.O., C.M.O.-A., A.O.F, I.A.B. and Y.A.A. were responsible for the study design, supervised the data collection, and contributed to the writing of the manuscript. F.A.O., C.M.O.-A. were responsible for data collection. F.A.O, C.M.O.-A, A.A and I.K.S. performed the laboratory work. C.M.O.-A and F.A.O. performed the data visualization and analysis. C.M.O.-A and F.A.O. were responsible for morphological identification of Aedes species. F.A.O., C.M.O.-and A., A.A. drafted the manuscript. All the authors read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eWe are grateful to the community members and field assistants for their support during sample collection and for granting permission to conduct the study within their localities. We also acknowledge the Port Health authorities at the Takoradi seaport for providing the necessary permits to carry out sampling within the port area.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eWeetman, D. et al. Aedes Mosquitoes and Aedes-Borne Arboviruses in Africa: Current and Future Threats. \u003cem\u003eInt J. Environ. Res. Public. Health\u003c/em\u003e \u003cb\u003e15\u003c/b\u003e (2018).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKamgang, B., Yougang, A. P., Tchoupo, M., Riveron, J. M. \u0026amp; Wondji, C. Temporal distribution and insecticide resistance profile of two major arbovirus vectors Aedes aegypti and Aedes albopictus in Yaound\u0026eacute;, the capital city of Cameroon. \u003cem\u003eParasit. Vectors\u003c/em\u003e. \u003cb\u003e10\u003c/b\u003e, 469 (2017).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMontgomery, M. et al. Spatial distribution of insecticide resistant populations of Aedes aegypti and Ae. albopictus and first detection of V410L mutation in Ae. aegypti from Cameroon. \u003cem\u003eInfect. Dis. Poverty\u003c/em\u003e. \u003cb\u003e11\u003c/b\u003e, 90 (2022).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNgoagouni, C., Kamgang, B., Nakoun\u0026eacute;, E., Paupy, C. \u0026amp; Kazanji, M. 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(Diptera: Culicidae) From Eastern and Southern Mexico. \u003cem\u003eJ. Med. Entomol.\u003c/em\u003e \u003cb\u003e57\u003c/b\u003e, 218\u0026ndash;223 (2020).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWHO. Standard operating procedure for testing insecticide susceptibility of adult mosquitoes in WHO tube tests. \u003cem\u003eWorld Health Organization\u003c/em\u003e, \u003cb\u003e16\u003c/b\u003e (2022a).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWHO. Standard operating procedure for testing insecticide susceptibility of adult mosquitoes in WHO bottle bioassays. \u003cem\u003eWorld Health Organization\u003c/em\u003e, 21 (2022b).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":true,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Aedes albopictus, Aedes aegypti, Invasive species, Insecticide resistance, kdr mutations, Ghana","lastPublishedDoi":"10.21203/rs.3.rs-7407322/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7407322/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn mid-2023, \u003cem\u003eAedes albopictus\u003c/em\u003e, a key dengue vector, was unexpectedly identified during \u003cem\u003eAnopheles\u003c/em\u003e surveillance in Takoradi, southwestern Ghana. \u003cem\u003eAe. albopictus\u003c/em\u003e is not known to be breeding in Ghana until this encounter. By mid-2024, the Ghana Health Service reported several outbreaks of dengue for the first time, with confirmed cases in several regions, including Takoradi. This study investigated the bionomics and insecticide susceptibility of \u003cem\u003eAe. albopictus\u003c/em\u003e through larval and adult surveys near the initial detection sites, including the seaport. Among 2,666 \u003cem\u003eAedes\u003c/em\u003e larvae collected, car tyres were the most productive habitat (66.4%). \u003cem\u003eAe. aegypti\u003c/em\u003e (87.2%) were the most abundant vector, followed by \u003cem\u003eAe. albopictus\u003c/em\u003e (12.2%). \u003cem\u003eAe. albopictus\u003c/em\u003e was fully susceptible to pyrethroids and pirimiphos-methyl, while \u003cem\u003eAe. aegypti\u003c/em\u003e was resistant to pyrethroids. PBO synergist assays restored susceptibility in \u003cem\u003eAe. aegypti\u003c/em\u003e. \u003cem\u003ekdr\u003c/em\u003e mutations were detected in both species: \u003cem\u003eAe. albopictus\u003c/em\u003e had low frequencies of \u003cem\u003eF1534C\u003c/em\u003e (0.18), \u003cem\u003eV410L\u003c/em\u003e (0.02), \u003cem\u003eV1016I\u003c/em\u003e (0.00) whilst \u003cem\u003eAe. aegypti\u003c/em\u003e showed high \u003cem\u003eF1534C\u003c/em\u003e (0.72), \u003cem\u003eV1016I\u003c/em\u003e (0.50), and \u003cem\u003eV410L\u003c/em\u003e (0.06). These findings provide essential baseline data for public health action and necessitate the urgent need for enhanced vector surveillance and resistance monitoring in Ghana.\u003c/p\u003e","manuscriptTitle":"Invasion of the Dengue Vector Aedes albopictus in the Port City of Takoradi, Southwestern Ghana","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-11 11:17:28","doi":"10.21203/rs.3.rs-7407322/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"60e693de-2475-4691-9bb3-50430b63c755","owner":[],"postedDate":"September 11th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":54452225,"name":"Health sciences/Diseases"},{"id":54452226,"name":"Biological sciences/Ecology"},{"id":54452227,"name":"Earth and environmental sciences/Ecology"},{"id":54452228,"name":"Biological sciences/Microbiology"},{"id":54452229,"name":"Biological sciences/Zoology"}],"tags":[],"updatedAt":"2026-04-08T05:55:50+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-11 11:17:28","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7407322","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7407322","identity":"rs-7407322","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}