Abstract

Accurate knowledge on the biting pattern of Anopheles gambiae sl is a prerequisites for mounting long lasting control intervention in malaria endemic areas. A descriptive study was undertaken to determine the hourly biting cycle of A. gambiae in some randomly selected communities in Bayelsa State, Nigeria during January, 2014 and December, 2015. The two methods used for mosquito collection were human baits (indoor and outdoor). Hourly mosquito collections were undertaken twice quarterly from 1900 to 0400 h. Mosquitoes collected were identified morphologically following a standard key. The hourly and seasonal biting rates of A. gambiae were calculated. Two thousand and seven female A. gambiae were identified in 16 man-night. The total bites were 62.72 bites/person/night. The mosquito biting rates were higher outdoor than indoor collections. Similar results were recorded for seasonal and ecovegetation collections. Wet seasons had higher mosquito biting rates (71.58 bites/person/night) than that of the dry seasons collection (36.358 bites/person/night). The biting rates of A. gambiae sl were 2-fold higher in fresh water than in brackish water swamp forest and mangrove coastal water forest. The hourly biting rates of A. gambiae peaked at 2300 h, while the seasonal biting rates peaked at 2300 h and 4 am. This result has demonstrated the inefficiency of the indoor residual spray (IRS) and long lasting insecticidal nets (LLNs) as the only malaria control measure in this area. Outdoor protective control measure is recommended alongside indoor IRS and LLNs.

Key words: Circadian, Seasons, biting patterns, Anopheles gambiae, Bayelsa State.