Relative abundance, distribution and diversity of Culex (Diptera: Culicidae) mosquito species in Lagos, Southwest Nigeria
Amao, H., Idowu, E. T., Oyeniyim T., Otubanjo, O. A. and Awolola, T. S
NJE Vol. 34: 39-49, 2018
Abstract: Culex mosquitoes are nuisance bitters and vectors of public and veterinary health importance. Information on the abundance and distribution of this species is critical in understanding the risk factors associated with the diseases transmitted by these vectors. A longitudinal survey was conducted from May 2015 to October 2016 to determine the abundance, distribution and species diversity of Culex mosquitoes in water drainage channels in Kosofe, Ojo, Epe and Eti-Osa Local Government Areas (LGAs) of Lagos State. Culex larvae were collected using standard dipper, counted and reared to adults. Samples collected were identified morphologically while members of Culex pipiens complex were further identified into subspecies using Polymerase Chain Reaction (PCR) assays. A total of 12,367 Culex larvae were collected, of which 64.4% and 35.6% were collected in canals and gutters respectively. Culex larvae were predominant at the end of wet season and beginning of the dry season with the highest population recorded in November. Kosofe LGA had the highest number of Culex immature stages (34.47%) followed by Ojo (31.13%), Eti-Osa (18.56%) and Epe (15.84%). Six species; Culex pipiens sensu lato (49.35%), Cx nebulosus Theobald (20.71%), Cx moucheti Evans (6.89%), Cx cinereus Theobald (10.43%), Cx decens Theobald (8.75%) and Cx tigripes Grandpre and Charmoy (3.87%) were identified. The abundance of members of Cx pipiens complex was significantly higher than that of the other five species (F = 7.760; df = 5; P<0.05). PCR assays of Cx. pipiens complex revealed the presence of Cx. pipiens quinquefasciatus as the only member of the group. Species dominance structure showed Cx quinquefasciatus as the only eudominant species in all the study locations. Diversity indices for the study areas varied from 1.220 to 1.643 for Shannon-Weiner (H’) and from 0.2104 to 0.4132 for the Simpson index (D).The wide range of Culex species encountered highlight the need for the mosquito surveillance and control in Lagos state because of their potential role in disease transmission.
Keywords: Distribution, Diversity, Drainage systems, Habitat productivity.