Habitat characteristics of Anopheles gambiae s.s. larvae in a Kenyan highland

Abstract

Anopheline larval habitats associated with a swamp, were examined in a highland area (1910 m elevation) of western Kenya. A significant association was found between occurrence of Anopheles gambiae Giles s.s. (Diptera: Culicidae) larvae and two factors, habitat size and vegetation type. Over 80% of An. gambiae s.s. larvae were found in small isolated pools, characterized by short plants, occurring in both swamp margins and roadside ditches. However, Anopheles gambiae s.s. was not found in habitats marked by papyrus and floating plants. The larval habitat of An. gambiae s.s. was characterized by warmer daytime temperatures of water, which were significantly affected by habitat size and plant size. The density of indoor resting An. gambiae s.s. was 0.22 per house and negatively associated with distance from the swamp. These results indicate that the practice of swamp cultivation, in populated areas of the African highlands, increases availability and enhances habitat conditions for the malaria vector.

Habitat Partitioning of Malaria Vectors in Nchelenge District, Zambia

“…gambiae mosquitoes are likely due to a wide range of temporary sunlit breeding habitats found throughout Nchelenge District such as animal footprints, puddles, and ground depressions formed due to heavy rains during the wet season. 3,41,42 In villages near Lake Mweru, An. gambiae larvae and pupae in oviposition surveys have been collected in puddles and boats onshore along the lake, as well as in ditches along the main road (unpublished data).…”

A breeding site model for regional, dynamical malaria simulations evaluated using in situ temporary ponds observations

“…Mosquitoes may exploit any available water for oviposition, natural or man-made (Imbahale et al, 2011;Fillinger et al, 2004), permanent or temporary (Fillinger et al, 2004), clean or polluted (Sattler et al, 2005;Awolola et al, 2007;Chinery, 1984) and of various sizes from hoof-prints of animals to the edges of large water bodies (Sattler et al, 2005;Mutuku et al, 2006b;Imbahale et al, 2011), although individual species have preferences of habitat type. For example, Anopheles gambiae complex mosquitoes, the principal malaria vector in Sub-Sahara Africa prefer temporary, sunlit water bodies for their breeding, which become abundant during the rainy season (Mutuku et al, 2006a;Minakawa et al, 2004), although their larvae have also been found in polluted waters (Imbahale et al, 2011;Awolola et al, 2007;Sattler et al, 2005).…”

“…Several studies have found these micro habitats to be productive and therefore their contribution to mosquito vector abundance, especially during the rainy season, should not be ignored in dynamical models (Bomblies, 2012;Imbahale et al, 2011;Sattler et al, 2005). For example, in western Kenya, Minakawa et al (2004) found more than 80% of Anopheles gambiae s.s. in isolated pools with water surface areas lower than 0.1 m 2 . Secondly, such pools are temporary and therefore contain fewer or no competitors and predators decreasing the larvae mortality rate (Koenraadt et al, 2004;Sunahara et al, 2002).…”

Source reduction of mosquito larval habitats has unexpected consequences on malaria transmission

“…Heterogeneity in adult mosquito productivity among various habitats is common in Africa (6,7,12,13). Recognition of the fact has led to the development of a framework for assessing the impact of larval interventions based on individual habitats (14).…”

“…However, field observations indicate that this may not be the case. For example, the absence of anopheline larvae in suitable habitats has been frequently documented (6,7,9,12,20), suggesting that mosquitoes might not be as efficient in locating oviposition sites as commonly assumed. On the other hand, intervention programs targeting aquatic habitats or preventing mosquitoes from accessing blood meals, such as using insecticide-impregnated bed nets, indeed resulted in altered gonotrophic cycles (21)(22)(23)(24).…”