The Spatial and Temporal Distribution Pattern of Culex Mosquitoes in Gazipur, Bangladesh

In recent years, Culex quinquefasciatus mosquitoes have become a significant nuisance and public health concern in urban areas. Existing control measures often fail due to a lack of ecological understanding of their breeding habits and population dynamics. To address this, a year-long longitudinal study was conducted throughout 2022 in the Ward 35 of the Gazipur City Corporation to identify breeding habitats and quantify population fluctuations. Larval collections identified four genera, namely Aedes, Culex, Mansonia, and Armigeres, with over 99% of Culex quinquefasciatus immature. The study recognized 12 different types of breeding habitats, with significantly varying immature productivity (df=11, F=15.645, P=0.000). There were six permanent and highly productive habitats. The highest contributor (25% of collected immature) was katcha drains followed by permanent wetlands (24%), pucca drains (22%), derelict ponds (10%), temporary wetlands, and manholes. Manholes and katcha drains were classified as critical reservoir habitats by supporting year-round immature production. Immature population density varied significantly across months (df=11, F=2.17, P=0.020). It peaked in March (1428/dip) and reached its lowest point in August (194/dip). A sharp population decline was observed from May (510/dip) onwards because of increased rainfall and higher temperatures. These findings suggest that effective Culex mosquito management practice should be initiated at the onset of the population acceleration phase in September in an integrated manner by including structural modification of kacca and pacca drains, routine application of biological agents, and biocides in wetlands and manholes, as well as operating community-based source reduction strategies to prevent the characteristic resurgence of the adult mosquito population during the peak season.