Breeding Habitat Preferences and Environmental Dynamics of Aedes Mosquitoes in Urban and Semi-Urban Areas of Ibadan, Nigeria

Aedes aegypti and Aedes albopictus are primary vectors of dengue, yellow fever, and chikungunya, with their breeding ecology and environmental adaptability influencing distribution and transmission dynamics. Effective control strategies require targeted larval habitat management, necessitating a comprehensive understanding of breeding patterns.

A longitudinal study (July 2017–April 2020) was conducted in the Ibadan North (urban) and Akinyele (semi-urban) Local Government Areas (LGAs) of Ibadan, Nigeria. Aedes eggs were collected using ovitraps, while larvae and pupae were sampled from natural and artificial habitats via the dipping method. Water quality parameters (temperature and dissolved oxygen) were recorded. Immature insects were reared to adulthood and identified using morphological keys.

A total of 4,429 ovitraps were positive, with ovitrap and egg density indices at 82.2% and 51.3%, respectively. Immature Aedes were found in 73.0% of breeding sites, with higher positivity in semi-urban (56.8%) than urban areas (43.2%). Artificial habitats dominated breeding sites (>88%), with disused tyres (13.1%) and plastic containers (12.1%) being the most common. Water temperature was significantly higher in urban areas (28.17°C ± 2.11) than semi-urban areas (27.85°C ± 2.01), while dissolved oxygen was higher in semi-urban sites (4.42 mg/L ± 0.94 vs. 4.08 mg/L ± 1.07). Adult A. aegypti emergence from ovitrap-collected eggs was higher in urban areas, whereas A. aegypti and A. albopictus from dipping-collected larvae were more abundant in semi-urban areas. House, Container, and Breteau indices exceeded WHO transmission thresholds, indicating a high risk of arboviral outbreaks.

The prevalence of artificial breeding sites, especially in semi-urban areas, highlights the need for targeted larval source reduction. Community-based interventions, including proper disposal of water-holding containers, are essential for effective vector control.