Physico-chemical parameters of Anopheles mosquito larval habitats and their effects on larval abundance in Osun State, Southwest, Nigeria

Abstract

Malaria remains endemic in sub-Saharan Africa. The present study investigates the effect of Anopheles larval habitat physico-chemical indices on larval abundance across the three senatorial districts of Osun State, Nigeria. Larval prospection was carried out weekly between 0700 h and 1100 h for a year (January to December, 2022). The collected larvae were conveyed to the laboratory of the Department of Animal and Environmental Biology, Osun State University, Osogbo, Osun State, Nigeria where they were morphologically identified. Water samples from the encountered larval habitats were collected and analyzed for physico-chemical properties such as pH, temperature, turbidity, alkalinity, hardness, conductivity and salinity using standard equipment and procedures. Additionally, the larvae abundance was calculated. 5343 Anopheles larvae were collected with their larval habitat temperatures ranging from 25.5 °C and 25.7 °C. There was a noticeable variation in temperature and larval abundance (p < 0.05). Ila with a temperature of 25.7 °C had the lowest larval abundance as compared to Inisa and Ipetumodu with a temperature of 25.5 °C and 25.6 °C respectively. The pH across the study areas was slightly alkaline between 7.04 and 7.48 and with a significant variation with the larval abundance (p < 0.05). The conductivity, hardness and salinity also varied significantly with the larval abundance (p < 0.05). The present study therefore reveals the effect of physico-chemical parameters on Anopheles larval abundance. Thus, indicating the stringent need for mosquito larval habitat surveillance through larval source management with a view to decimating the larval habitat which invariably reduces residents’ exposure to malaria and other Anopheles-borne diseases.