Effect of seasonal variation on the resting behavior of Aedes species (Diptera: Culicidae) in Metema district, Northwest, Ethiopia

Abstract Background: Aedes mosquitoes transmit several medically important viral diseases, including dengue fever, yellow fever, chikungunya, and Zika. These diseases have re-emerged as major global public health concerns due to increasing urbanization, rising temperatures associated with climate change, and intensified human mobility. Seasonal variation, particularly between the wet and dry seasons, influences the distribution and resting behavior of Aedes species in the Metema District of northwestern Ethiopia. Method: Adult Aedes mosquitoes were collected from both indoor and outdoor resting habitats, including grain storage facilities, deep ground grooves, cattle shelters, water-holding containers, and under bridges. Collections were conducted using pyrethrum spray catches (PSC), Prokopack aspirators, and mouth aspirators. Captured mosquitoes were identified to species level under a stereomicroscope using standard morphological identification keys. Data were entered and analyzed using IBM SPSS Statistics version 20.0. Results: A total of 4,054 adult Aedes mosquitoes were collected, comprising Aedes aegypti (3,026; 74.6%), Ae. vittatus (723; 17.8%), Ae. communis (186; 4.6%), Ae. albopictus (77; 1.9%), and Ae. opok (42; 1.0%). Significantly higher numbers of Ae. aegypti and Ae. vittatus were collected from cattle shelters than from other resting habitats ( P < 0.001). Adult Ae. communis and Ae. albopictus were primarily collected from larva-positive water containers, whereas Ae. opok was predominantly collected from beneath bridges. The abundance of adult Aedes mosquitoes peaked during the wet season (June–September 2023). In contrast, during the dry season (October–May), Aedes mosquitoes were mainly found resting in deep ground grooves and beneath bridges. A high proportion of blood-fed Aedes mosquitoes was collected from cattle shelters. The predominance of Ae. aegypti and Ae. vittatus in cattle shelters during the wet season is likely associated with the availability of carbon dioxide, host body heat, and protection from adverse environmental conditions. During the dry season, the resting behavior of Aedes mosquitoes shifted toward moisture-retaining habitats, such as deep ground grooves and the undersides of bridges. Conclusions These findings highlight the importance of implementing targeted Aedes mosquito control strategies that account for seasonal variation and resting habitat preferences. Particular emphasis should be placed on managing key resting sites in urban areas, especially cattle shelters during the wet season and moisture-retaining refuges during the dry season. Strengthening entomological surveillance and implementing seasonally targeted vector control interventions could substantially reduce the risk of Aedes -borne viral disease transmission in the Metema District, northwestern Ethiopia.