Larval habitat diversity and Anopheles mosquito species distribution in diferent ecological zones in Ghana

Abstract

Background: Understanding the ecology of larval malaria and lymphatic flariasis mosquitoes in a changing envi ronment is important in developing efective control tools or programmes. This study characterized the breeding habitats of Anopheles mosquitoes in rural communities in diferent ecological zones in Ghana during the dry and rainy seasons. Methods: The spatio-temporal distribution, species composition, and abundance of larval Anopheles mosquitoes in breeding habitats were studied in fve locations in three ecological zones of Ghana. These were Anyakpor (coastal savannah area), Duase (forest area), and Libga, Pagaza, and Kpalsogu (Sahel savannah area). Larvae were collected using standard dippers and were raised in the insectary for identifcation. Results: Out of a total of 7984 mosquito larvae collected, 2152 (27.26%) were anophelines and were more abundant in the rainy season (70.82%) than in the dry season (29.18%). The anophelines comprised 2128 (98.88%) An. gambiae s.l., 16 (0.74%) An. rufpes, and 8 (0.37%) An. pharoensis. In the coastal savannah and forest zones, dug-out wells were the most productive habitat during the dry (1.59 larvae/dip and 1.47 larvae/dip) and rainy seasons (11.28 larvae/dip and 2.05 larvae/dip). Swamps and furrows were the most productive habitats in the Sahel savannah zone during the dry (0.25 larvae/dip) and rainy (2.14 larvae/dip) seasons, respectively. Anopheles coluzzii was the most abundant sibling species in all the ecological zones. Anopheles melas and An. arabiensis were encountered only in the coastal savan nah and the Sahel savannah areas, respectively. Larval habitat types infuenced the presence of larvae as well as larval density (p<0.001). The land-use type afected the presence of Anopheles larvae (p=0.001), while vegetation cover infuenced larval density (p<0.05). Conclusion: The most productive habitats were dug-out wells in the coastal savannah and forest zones, and furrows from irrigated canals in the Sahel savannah zone. Anopheles coluzzii was the predominant vector species in all the eco logical zones. The abundance of Anopheles breeding habitats and larvae were infuenced by anthropogenic activities. Encouraging people whose activities create the larval habitats to become involved in larval source management such as habitat manipulation to stop mosquito breeding will be important for malaria and lymphatic flariasis control.