Seasonal Distribution and Micro-Climatic Factors Influencing the Abundance of the Malaria Vectors in South-East Nigeria

Abstract

The longitudinal study was conducted in the South-east of Nigeria from April, 2013 to February 2014 to investigate the seasonal abundance of anophelines and their correlation with microclimatic variables. Sampling of Anopheles mosquitoes was done using WHO light traps and Pyrethrum Spray Catch (PSC). ANOVA and Spearman’s rho correlation analysis were used to analyze the link between mosquito abundance, seasonal variations, temperature and relative humidity. A total of 1,570 female Anopheles mosquitoes, representing 4 species were collected. Seasonally, the collections made reflected a sigmoid curve with the peak being the late rainy season (42.42%), early rainy season (42.29%) and dry season (15.29%). There was a significant difference (P 0.05). The hourly distribution for indoor biting mosquitoes peaked at 2 am-3 am and outdoor 3 am-4 am. Using the PSC collection technique, 3 groups of Anopheles species were collected. Indoor resting density of 1 Anopheles mosquito/room/night and Man-biting rate of 5.5 Anopheles mosquito / man / night was observed. The findings in the study therefore gives a direction to take in the control of malaria vectors in Ahani Achi, Oji River of Enugu, knowing the seasonal variation of the malaria vectors, their biting behaviour, climatic exposure and the likely human behaviour that encourages the biting tendency of the mosquito.