Spatiotemporal Distribution and Composition of Anopheles Mosquito Species in Some Selected Eco-Settings of Nasarawa State North Central Nigeria

Abstract

Mosquitoes are known to be notorious for their ability to constitute a nuisance as well as transmit disease-causing organisms (pathogens) to hosts. This study was aimed to determine the species distribution, abundance, and diversity of mosquitoes in three selected eco – settings of Nasarawa State, Nigeria. Anopheles mosquitoes were sampled using Pyrethroid Spray Catch (PSC) technique and were identified morphologically using keys. A total of Fifteen thousand, four hundred and seventeen (15,417) mosquitoes vector genera were encountered in the study areas between the period of January to December, 2017 and 2018. Of the 15417 (100%) mosquitoes encountered or sampled, 9881 (64.09%) were anopheline while 5536 (35.91%) were culicine. Statistical analysis showed that there is a highly significant difference (p<0.05) in the relative abundance of mosquito genera vector across the eco – settings studied. Out of the 9881 (64.09%) anopheline mosquitoes caught during the study period, the highest being 1273 (12.88%) were caught in the month of May followed by June 1222 (12.37%) while the least number of anopheline mosquitoes were recorded in the month of February 534 (5.40%). Six (6) species of Anopheles mosquito vectors were encountered in all the selected eco – settings of Nasarawa State. The various species encountered are as follows; Anopheles gambiae s. l, An. funestus, An. nili, An. coustani, An. rufipes and An. pharoensis. An. gambiaes. l were the most dominant species (41.89%) encountered across the eco – settings during the two seasons followed by An. coustani (19.49%) while An. pharoensis had the least number of species (5.83%) across the eco – settings. Statistically, there is a significant difference (p<0.05) in the spatial composition of Anopheles mosquito species encountered across the selected eco – settings of Nasarawa State. This study revealed that Anopheles species were higher in terms of abundancewhich is very important vectors of malaria in Nigeria. These results indicated that vectors of mosquito bornediseases are breeding in the study area, most of which are encouraged by human activities.