This is a pioneer study carried out toward southwest of Colombia in the Department of Cauca. The study, revealed the presence of four species of mosquitoes (Culicidae) in the urban area of Santander de Quilichao. The results showed a strong association between the two seasons evaluated and the ecological distribution patterns of the various mosquito populations studied. Thus, the results obtained here are consistent with other studies which confirmed the high abundance of Culicidae in the rainy season (Bedoya-Rodríguez et al 2021, De Melo et al 2021, Omar et al 2021, Maquart et al 2021b). There is a relationship and dependence of water on reproduction in this insects. Likewise, the tropical dry forest climate favors the proliferation of mosquitoes due to its relative annual thermal stability. It is obvious that high temperatures benefit these organisms that lack physiological thermoregulation systems. These ecophysiological conditions make the prevalence of VBD particularly in tropical latitudes (Verhulst et al 2020, De Melo et al 2021). For example, the epidemiological presence of dengue fever in the Department of Cauca generate a situation of alert. This disease is the second most prevalent disease after malaria (INS 2023). Specifically, statistical data from the department show an impact of VBD in the municipality of Santander de Quilichao, which are consistent with this ecological study. It is noting the presence of more dengue cases in the second trimester than the third trimester of 2022 (Fig. 5), which coincides with the greater abundance of mosquitoes collected in the rainy season than the dry season. In addition, the Culicidae family, especially Aedes species, have been vectors directly associated with dengue and have been studied in various urban sectors of Colombia (Carrasquilla et al 2021, Talbot et al 2021).
This study reported the presence of two species of Aedes which are potential VBD. Analyzing the epidemiological data provided for Secretaria de Salud (2022), 13040 cases of VBD were reported during 2015 to 2019. 69% correspond to malaria, 16.9% to dengue and 14.1% were associated with other VBD in the department of Cauca. Along the first trimester of the year 2022, Santander de Quilichao was the municipality with the highest notification of VBD with 24 cases of dengue fever. This is a high risk to the populations of this municipality due to incidence rate of severe dengue fever (Saludcauca 2022). The cases reported in the second trimester (7 cases), third trimester (4 cases) and fourth trimester (11 cases) of that year demonstrated that carry out studies on the ecology and abundance of mosquitoes are important (INS 2022) (Fig. 5).
In this sense, it is notorious that natural and artificial habitats provide favorable conditions for mosquito development. This study, carried out in an urban sector, with a large presence of green areas and without construction, is considered another important factor for the presence of Culicidae. In fact, all these factors can contribute to the formation of stagnant waters where there are no natural predators. On the other hand, human presence and inadequate management practices to prevent the proliferation of mosquitoes, potentiate their development and offer a relatively high resource for their hematophagous activity, which is key to obtain areas for their reproduction (Foster & Walker 2019). This research shows that Aedes aegypti is the species with the highest richness in urban sectors, coinciding with works such as Cardoso et al (2020), Juma et al (2021) and Rahman et al (2021a). Is the richness was ratified with multivariate analyses nMDS, ANOVA and rarefaction curve which determined significant relationships between abundance variables of mosquitoes and the sampling locations. This result obtained here was consistent with studies realized in other countries. Those studies, confirmed that Aedes aegypti has developed a great adaptive capacity which impact its evolution in urban environments. In consequence, this species has been able to establish and colonize a great diversity of biomes and compete with other species of Culicidae (Juma et al 2021, Deblauwe et al 2022).
It is worth mentioning that the mosquitoes were historically considered as the first arthropod associated with the intermediate of parasites (Foster & Walker 2019). In particular, the Aedes aegypti species originated in Africa and spread globally in the tropics through commercial and human transport (Bennett et al 2016, Campos et al 2020). In this study, Aedes aegypti and Culex quinquefasciatus were the most abundant species present in the five sampling points, which shows their great adaptive capacity at the reproductive level. Those species showing affinity with artificial habitats such as used tires and natural habitats in the case of tree holes (Juma et al 2021, Deblauwe et al 2022). In Qatar, the research conducted by Farag et al (2021) coincides with our study. The habitats where Culex quinquefasciatus can develop were similar to the areas sampled in our study. However, in the case of Aedes aegypti, they founded that the desert climatic conditions affect the presence of this specie in urban area. Therefore, there is a low risk of disease transmission by this vector. This demonstrate that tropical and subtropical climates are ideal for the reproduction of Aedes, while in desert climates its presence is practically null. On the other hand, Aedes is a mosquito with great capacity to transmit diseases which has been demonstrated by numerous studies aborting VBD around the world (Silva et al 2020, Semenza & Paz 2021). Likewise, in the case of dengue fever in Colombia, there have been outbreaks with high lethality this country and in the American continent (Gutierrez-Barbosa et al 2020).
The third most abundant culicid in the present study was Aedes albopictus, which together to Aedes aegypti represent the most relevant vectors of VBD and of health interest such as dengue, zika, chikungunya and yellow fever (Câmara et al 2020, Lowe et al 2021, Shin & Jung 2021, WHO 2020). For this reason, it is important to control these vectors in the region. Muñoz et al (2021), stablished that the Niño phenomena is related with the increase of dengue cases. Numerous strategies have been established for disease vector intervention and control. One effective experience to control diseases is using Wolbachia bacteria. The infection of this bacteria on Aedes reduces its ability to transmit diseases since the bacteria to hinders the reproduction of the virus (Lee et al 2020, Nirmani et al 2021). Likewise, avoid the use of insecticides. The use of constant and massive insecticides has generated resistance on certain populations of Aedes aegypti have developed evolutionary resistance to insecticides. Hence, the importance of establishing other innovative strategies for the control of these vectors (Boyer et al 2022). However, in the municipality of Santander de Quilichao, no such interventions have yet been carried out.
On the other hand, the research concluded that sampled points 1 and 4 are similar in terms of diversity and abundance of mosquitoes and the physical characteristics. Point 1 characterized by a recreation area with vegetation and point 4 is a sector without buildings with abundant vegetation. This kind of space provides a wide variety of places where mosquitoes can develop (Hernandez-Colina et al 2021). Although, not only the influence of the landscape is important in the presence of mosquitoes, this must be associated with climatic factors such as rainfall, temperature, humidity, between others. Those factors together influence the impact of mosquitoes in the regions (Francisco et al 2021). In this sense, the rainy season influence the abundance of mosquitoes, which is reflected in the increase of optimal places, natural and artificial, for their development (Maquart et al 2021b). The influence of the dry season (from June to August) in the department of Cauca showed a little rainfall (Gobernación del Cauca 2019), favoring the presence of the species studied. The variations would be related to the Niña phenomena (Muñoz et al 2021). It is evident that during 2022, there was some precipitation in July which favor the presence of mosquitoes (IDEAM 2022).
On the other hand, the least frequently encountered species was Psorophora ferox. This suggests the possibility of not encountering optimal environments and habitats spaces for their reproduction. However, it should be noted that their diet does not depend solely on mammals, but also on birds (Ramalho-Ortigao & Gubler. 2020) which are frequent in the study area. The richness of this species could occur in other environments where human presence is not necessarily present. However, for our study, this species presented higher abundance in the rainy season, which coincides with the study of Orlandin et al (2021), where the positive sampling of the species occurs in high rainfall environments. The species was also present in the dry season but in scarce number. This confirmed its possible resistance to climatic transitions (Ceretti-Junior et al 2020).
Climate change and the biodiversity crisis associated with the absence of some species and ecosystems and also enhanced by anthropogenic activity have been shown to increase the spread of VBD (Williams et al 2021). These impacts reflect the increase in species that transmit these infectious diseases, which leads to the need for better vector control in both urban and rural sectors. This work provides an important starting point to establish entomological studies in the Cauca region. This study will help to improve preventive vector practices by the health sector and reduce the risk in the community due to the knowledge of the ecology of these species.
Finally, our work provides relevant information on the diversity of Culicidae mosquitoes, due to their sanitary interest. It is of great importance to consider, in future studies factors such as the sociodemographic factors of the population, vector capacity, genetic diversity and how they influence the abundance of mosquito. Equally, the necessity of carry out studies in relation to the knowledge, attitude and practice of the community regarding the mosquito and VBD. Hence, it is important of citizen participation in educational campaigns about vector control at home.