Chapter Iii. Anopheles Larval Productivity In Natural...

Chapter III. Anopheles larval productivity in natural habitats and the role of grass volatiles on oviposition preferences by An. arabiensis and An. coluzzii 3.1. Introduction Oviposition site selection by gravid Anopheles malaria mosquitoes is a key moment in the reproductive success of the individual, and thus the population dynamics of the species (Ndenga et al., 2011; White et al., 2011b). Consequently, the search for an oviposition site has important implications with regard to the control of malaria vectors (White et al., 20112b). When insects select oviposition sites, they make choices on increasingly fine spatial scales, starting with selecting a habitat in which to search (Hambà ¤ck et al., 2009; Raffa et al., 2016; Webster and†¦show more content†¦Vegetation often populates these wetland habitats (Ndenga et al., 2011; Fillinger et al., 2004; Minakawa et al., 2012), and An. gambiae/An. coluzzii and An. arabiensis are commonly found amongst cattails (Typha spp.; Typhaceae) and dallis grasses (Paspalum spp.; Poaceae) (Bà ¸gh et al., 2003; Gouagna et al., 2012; Khater et al., 2013). In contrast, habitats populated by reeds (Phragmites spp. ; Poaceae) and papyrus (Cyperus papyrus; Cyperaceae) generally produce low numbers of mosquitoes (Fillinger et al., 2004; Goma, 1960; Yohannes et al., 2005), probably due to the natural oil production of these species that reduces larval survivorship (Mouchet et al., 1998; Lindsay and Martens, 1998). Hence, grasses appear to play an important role in the natural breeding site selection of An. arabiensis and An. gambiae/An. coluzzii. Yet, the influence of natural grasses and other emergent vegetation on the oviposition site selection by gravid female Anopheles mosquitoes is not clearly understood. Moreover, the nature of the volatiles emitted from wild grasses and how they affect the behaviour of An. arabiensis and An. gambiae/An. coluzzii has not been investigated to date. The objective of this study was to investigate anopheline larval occurrence and abundance in natural