Species composition and abundance of mosquitoes of a tropical irrigation ecosystem

Exophagic-anthropophilic mosquitoes were collected during the April 2007-January 2008 planting season in four designated milet and guinea-corn irrigaton fields sampled in Gezawa Agro-ecological Zone of North-central Nigeria. Gezawa-1, Gezawa-2, Ketawa and Jogana irrigaton fieldscontributed about 31.2 %, 24.8 %, 22.8 % and 21.2% respectvely, to the number of mosquito species collected in the zone. There was preponderance of Anopheles gambiae complex (20.7 %) over Culex quinquefasciatus (11.8 %), C. pipiens fatigans (9.0%), A. funestus complex (7.0 %), Aedes aegypti (6.9%), A. albopictus (6.6 %), C. ppiens pipiens (5.7 %). C tigripes (5.0%), A. pharoensis (3.7 %), A africanus (3.6%), A. taylori (3.4%), A. coustani (3.3 %), A. luteocephalus (2.9 %), A. vittatus (2.8 %), A. rhodesiensis (2.1 %) Mansona (2.0 %) A. simpsoni (1.9 %) and Psorophora species (1.6 %). A Shannon-Wiener and Simpson’s diversity values of 1.1431 and 0.0925 were recorded for the mosquito species in Gezawa Agricultural Zone. A. gambiae had the highest Shannon-wiener diversity and Simpson’s dominance indces of 0.1415 and 0.0427 respectively. There was no significant difference between species diversity for the four irrigation fields (P>0.001). Vector control mustbe carried out in the irrigation fields to reduce the number ofthese out-door biting mosquitoes, since total reliance on ACTs and ITNs could not offer full protection against malaria to farmers in Gezawa irrigation fields. Keywords: Mosquitoes, Composition, Diversity, Dominance, Tropical ecosystem, Irrigation