Postirrigation Breeding Patterns of Surface Water Mosquitoes in the Mahaweli Project, Sri Lanka, and Comparisons with Preceding Developmental Phases

Abstract

A 2-yr (1988-1989) survey of mosquitoes breeding in surface water was done in an area of the Mahaweli Project of Sri Lanka that underwent irrigation development and human settlement during the preceding 3 yr. In total, 78,649 immatures of 42 species were collected during the survey. Species of medical importance in the area were Anopheles annularis van der Wulp, An. culicifacies Giles, An. jamesii Theobald, An. nigerrimus Giles, An. subpictus Grassi, An. vagus Doenitz, An. varuna Iyengar, Mansonia annulifera (Theobald), Ma. uniformis (Theobald), Culex fuscocephala Theobald, Cx. gelidus Theobald, Cx. pseudovishnui Colless, Cx. tritaeniorhynchus Giles, and Cx. vishnui Theobald. These and other species used breeding habitats associated with irrigation development (i.e., canals, reservoirs, seepage pools, and rice fields) as well as natural habitats (i.e., rainwater pools, riverbed pools, streams, and marshes). Trends in the use of breeding habitats that were observed with the onset of irrigated rice cultivation in 1987, continued during the period under stable irrigation in 1988 and 1989. Mosquito species richness declined, but species equitability (as indexed by Shannon-Weaver diversity values) did not change. The overall study showed that ecosystem changes concomitant with irrigation development in the Mahaweli Project resulted in long-term changes in the composition of the mosquito fauna, which was characterized by the increasing dominance of species with the potential to transmit human pathogens.

Escalating chronic kidney diseases of multi-factorial origin in Sri Lanka: causes, solutions, and recommendations

“…Therefore, it is not surprising, and in fact inevitable that negative consequences began to manifest years or even decades later [101]. In this regard, the Mahaweli River development and resettlement program in the dry zonal area in the NCP require special scrutiny [102][103][104] (The distribution of the River Mahaweli in relation to the CKD-mfo affected areas is illustrated in Fig. 1d).…”

“…Since the initiation of this programme, which included newer fast-flowing hydraulic technologies, from an environmental point of view, things have worsened [37,102,104,105]. It is plausible that this acceleration of irrigation project and human settlements have contributed to the current CKD-mfo epidemic [37], but there is no direct evidence.…”

The Global Public Health Significance of Plasmodium vivax

“…Sibling species that are morphologically indistinguishable and often sympatric within an area can have such varied bionomics that one sibling is rendered a dominant vector and the other a non-vector (Meek, 1995;Manguin et al, 2008). The proper identification of species and knowledge of their ranges, often rapidly altered by expanding agriculture and land use changes (Amerasinghe et al, 1991a;Amerasinghe and Indrajith, 1994;Lee, 1998;Singh and Mishra, 2000; Vythilingam et al, 2005), is vital for appropriate allocation of vector control resources.…”

Impact of dams and irrigation schemes in Anopheline (Diptera: Culicidae) bionomics and malaria epidemiology

“…However, this secondary vector was not able to maintain the incidence at the same levels than when An. culicifacies was the main responsible for Plasmodium transmission in the same area during preceding rice developmental stages 1,2,66 .…”