Effects of irrigation on mosquito populations and mosquito‐borne diseases in man, with particular reference to ricefield extension

Abstract

The modification by man of his environment, particularly for large‐scale irrigation and ricefield extension, often results in increased incidence of mosquito‐borne disease in associated human populations. Habitat modification leads to changes in the species composition of mosquitoes and thus the variety of disease agents to which man is exposed. Increased acreage of water attracts birds which act as hosts of arboviruses while a raised water table leads to marginal marshy areas and humid peripheral vegetation. These two aspects of the environment favour extended breeding and survival respectively. Higher atmospheric humidity enhances mosquito survival and the transmission of disease. Associated urban resettlement encourages domestic mosquito species and effects the distribution and abundance of vertebrates which may act as hosts of disease agents.