Morphometric studies on Culex quinquefasciatus and Mansonia africana (Diptera: Culicidae) in Abeokuta, south-western Nigeria.

Some of the important mosquito species are generally sympatric in terms of their geographical distributions, and are difficult to identify based solely on examination of adult females using the available morphological keys. In this study, adult mosquitoes were collected indoors in Abeokuta in south-western Nigeria between August 2005 and July 2006 using Center for Disease Control light traps. The objective was to investigate possible morphological differences in populations of Culex quinquefasciatus and Mansonia africana. Six morphological characters namely, wing length, antennal length, proboscis length, foreleg length, mid leg length and hind leg length were measured in the two species. A total of 868 Cx quinquefasciatus and 962 M. africana were collected during the study period. The mean length was observed to be higher in most characters during the wet season than the dry season but the variation was not statistically significant (P > 0.005). In M. africana, the antennal length, proboscis length, foreleg length and midleg length showed one peak each. The wing length exhibited three peaks while hind leg length showed two peaks. For Cx quinquefasciatus, the antennal length, proboscis length, foreleg length, mid leg length and hind leg length indicated one peak. The wing length however showed three peaks. Each of the peaks observed in wing length and hind leg length of M. africana and wing length of Cx quinquefasciatus was assumed to be a specific population. The coefficient of differences (CDs) for each population indicated the presence of three populations in M. africana (CD > 1.28). However, the hind leg length showed that the two populations were the same (CD < 1.28). Three populations were also obtained from CD for wing leg length of Cx quinquefasciatus (CD > 1.28). Other characters indicated the presence of only one population. The results therefore underscore the need to investigate the status of the two species in relation to species complex.

Mosquito larval habitats and public health implications in Abeokuta, Ogun State, Nigeria.

The larval habitats of mosquitoes were investigated in Abeokuta, Nigeria in order to determine the breeding sites of the existing mosquito fauna and its possible public health implications on the residents of the City. The habitats were sampled between August 2005 and July 2006 using plastic dippers and a pipette. The habitats were grouped as ground pools/ponds, gutters/open drains, tyres, domestic containers and treeholes/ leaf axils. Ten species of mosquitoes were encountered in the five habitats namely Mansonia africana, M. uniformis, Culex quinquefasciatus, Aedes aegypti, Ae. albopictus, Ae. vittatus, Cx tigripes, Anopheles gambiae s.l., An. funestus and Eretmapodite clnysogaster. Ae. aegypti bred in all the habitats sampled while Cx quinquefasciatus bred in four habitats except tree holes/leaf axils. An. gambiae s.l and Ae. albopictus occurred in three habitats while other species bred only in one or two habitats. Ground pools and domestic containers recorded the highest number of species followed by gutters/open drains. Tree holes/leaf axils was the least preferred habitat with the lowest number of species occurrence. However, statistical analysis revealed non-significant difference in species occurrence in the five habitats. The availability of the habitats to support the breeding of Aedes, Culex and Anopheles, which are known vectors of urban yellow fever, lymphatic filariasis and malaria suggest that the residents ofAbeokuta City are at risk of mosquito-borne diseases. It is important that residents of the City are enlighten on the environmental factors that contribute to mosquito breeding and that the Government should institute proper sanitation measures to reduce mosquito breeding sites.

Mosquito larval habitats and public health implications in Abeokuta, Ogun State, Nigeria

Abstract: The larval habitats of mosquitoes were investigated in Abeokuta, Nigeria in order to determine the breeding sites of the existing mosquito fauna and its possible public health implications on the residents of the City. The habitats were sampled between August 2005 and July 2006 using plastic dippers and a pipette. The habitats were grouped as ground pools/ponds, gutters/open drains, tyres, domestic containers and treeholes/ leaf axils. Ten species of mosquitoes were encountered in the fi ve habitats namely Mansonia africana, M. uniformis, Culex quinquefasciatus, Aedes aegypti, Ae. albopictus, Ae. vittatus, Cx tigripes, Anopheles gambiae s.l., An. funestus and Eretmapodite clnysogaster. Ae. aegypti bred in all the habitats sampled while Cx quinquefasciatus bred in four habitats except tree holes/leaf axils. An. gambiae s.l and Ae. albopictus occurred in three habitats while other species bred only in one or two habitats. Ground pools and domestic containers recorded the highest number of species followed by gutters/open drains. Tree holes/leaf axils was the least preferred habitat with the lowest number of species occurrence. However, statistical analysis revealed non-signifi-cant difference in species occurrence in the fi ve habitats. The availability of the habitats to support the breeding of Aedes, Culex and Anopheles, which are known vectors of urban yellow fever, lymphatic fi lariasis and malaria suggest that the residents of Abeokuta City are at risk of mosquito-borne diseases. It is important that residents of the City are enlighten on the environmental factors that contribute to mosquito breeding and that the Government should institute proper sanitation measures to reduce mosquito breeding sites