Diversity and distribution of macro-invertebrates associated with Anopheles gambiae breeding habitats in selected villages along River Sezibwa, Uganda

Abstract

Members of the Anopheles gambiae sensu lato (s.l.) are among the main vectors that carry Plasmodium which causes malaria. Immature stages of the vectors and other associated species share breeding habitats with other macro-invertebrates. The aim of this study was to investigate the diversity and distribution of macro-invertebrates associated with An. gambiae s.l. breeding habitats and the effect of water parameters in selected villages along River Sezibwa, Uganda. In this study, breeding habitats were categorized as: ponds, streams, temporary pools and roadside ditches. Dominant land use types were noted. Water physico-chemical parameters were determined, samples of Anopheles complex and other macro-invertebrates collected and preserved in 80% ethanol and morphologically identified to family. A total of 13,427 macro-invertebrate samples belonging to 18 families and 816 An. gambiae s.l. larvae were collected. Habitat types had significant effect on the abundance and diversity of macro-invertebrates. Ponds had the highest diversity of macro-invertebrates followed by streams, temporary pools and roadside ditches. Pond water spiders (Cybaeidae), crawling water beetles (Haliplidae), riffle beetles (Elmidae), predacious diving beetles (Dytiscidae) and backswimmers (Notonectidae) were the first five more abundant families in ponds than other habitats while water scorpions (Nepidae), mayflies (Baetidae), damselflies (Coenagrionidae), dragonflies (Aeshnidae), leeches (Hirudidae) were abundant in streams. Culex sp. (Culicidae), midges (Chironomidae) and water mites (Sphaerolichidae) were the first three more abundant families in temporary pools while ground beetles (Carabidae) was dominating in roadside ditches. Baetidae, Aeshnidae, Gerridae, Chironomidae and Haliplidae were significantly negatively correlated to the densities of An. gambiae s.l. larvae in ponds, Coenagrionidae and Notonectidae in streams, Baetidae and Carabidae in temporary pools and Baetidae in roadside ditches. Further studies should be conducted to establish the possible causes of the negative associations observed between some macro-invertebrates and An. gambiae s.l. larval densities in different habitats.