The role of unused swimming pools as a habitat for Anopheles immature stages in urban Malindi, Kenya

Abstract

We conducted larval surveys in habitats located in urban Malindi, Kenya, in 2005 and 2006 with the goal of determining the productivity of unused swimming pools in relation to other habitats. Of the 250 habitats sampled, 66 were unused swimming pools, 93 were wells, 60 were drainage troughs, and 31 were miscellaneous areas, such as septic tanks, swamps, concrete tanks, fish ponds, car-track depressions, and drainage ponds. Anopheles gambiae s.1. was the only anophelines species found in the habitats, whereas Culex quinquefasciatus made up > 95% of all culicine immature stages found. Of the 110 habitats found to be positive for mosquitoes, unused swimming pools represented 42.7%. One hundred and forty-eight anopheline pupae were found in 8 of the 66 unused swimming pools, but none was found in the other habitats. Using a nonparametric test, Kruskal-Wallis H test, there was no significant difference in the abundance of culicine pupae found in the 4 habitat types (chi2 = 7.350, df = 3, p = 0.062). Unused swimming pools in Malindi provide ideal habitats that should be targeted for mosquito control.

Fig. 1

Pictures illustrating unused swimming pool in up-market areas of Malindi (A) on the grounds of a private residential home and (B) on the grounds of a tourist hotel.

Fig. 2

Mosquito density (number of mosquitoes per habitat) of (A) Anopheles immature stages and (B) culicine immature stages sampled from swimming pools (n = 66), wells (n = 93), drainage troughs (n = 60), and other miscellaneous habitat types (n = 31; i.e. septic tanks, swamps, concrete tanks, fish ponds, car-track depressions, and drainage ponds) located in different urban areas of Malindi, Kenya.