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Journal of Parasitic Diseases: June 2006, Vol. 30, No. 1, 45–52J P DMosquito breeding in riceland agro-ecosystem nearChennai, Tamil Nadu, India1 2J. Ravindran and J. Williams1Integrated Disease Vector Control Project (National Malaria Research Institute), Field Station, Chennai.2P. G. and Research Department of Zoology, Loyola College, Chennai.ABSTRACT. Breeding ecology of mosquitoes was studied in riceland area near Chennai during theperiod 1992-1999. The study area was a transition zone with withdrawal of intense agriculturalactivities to facilitate urbanization. A myriad of mosquitoes including potential vectors of malariaand Japanese encephalitis (JE) were observed breeding in various habitats present. A longitudinalsurvey showed no malaria vector breeding in rice fields. Extensive breeding of Culextritaeniorhynchus (JE vector) was observed. Natural breeding pattern indicated peak anophelineand culicine density during first two weeks after transplantation. Pre- and post-monsoon surveysin irrigation wells indicated breeding of 16 species of mosquitoes. Both Anopheles stephensi and An.culicifacies, the urban and rural malaria vectors, respectively, were encountered breeding in thewells; An. stephensi breeding was predominant. Observations on species-specific habitatpreferences showed An. stephensi to breed extensively in open wells and An. culicifacies inpuddles/bed pools. Cx. tritaeniorhynchus was found breeding in almost all types of habitatssurveyed. In retrospective, the study revealed information on mosquito species breeding in varioushabitats, which may be helpful for optimizing species sanitation.Keywords: breeding habitats, immature stages, vectorsINTRODUCTIONRice is the staple food in India, and its cultivation hasbeen traditionally carried out under differentgeographical and climatic conditions (Singh et al.,1989). Modern irrigation facilities and plant breedingtechnologies have resulted in increased acreage andcultivation of rice crops throughout the year leading toits increased production. Unfortunately, along withincreased production it has also led to widespreadoutbreaks of mosquito borne diseases like malaria andJapanese encephalitis (JE; Lacey and Lacey, 1990).Corresponding author: Dr. K. John Ravindran, IntegratedDisease Vector Control Project (NMRI), 332-A, SpartanSchool Road, Paneer Nagar, Mogappair, Chennai-600 037,Tamil Nadu, India. E-mail: johnravindran@gmail.comFor their breeding, mosquitoes are known to exploitaquatic habitats present in riceland agro-ecosystem.Any change in this ecosystem, either naturally or manmade, tend to alter the biotic community includingmosquitoes, which may be advantageous ordisadvantageous for mankind. Therefore, informationon mosquito fauna and breeding ecology in atransitory environment is imperative for successfulintervention. Ongoing urbanization in agriculturalarea in the outskirts of Chennai, Tamil Nadu, India,resulted in an ecologically transitional region, whichreceived our attention. Information on breedingecology of mosquitoes in this environment may behelpful to ensure preparedness for effective vector anddisease control.