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Mosquito breeding in riceland agro-ecosystem near Chennai51Table V. Interspecific associations among important vector mosquitoes in study areaHabitat Species Interspecific Index ofassociation (C ) association (I)Domestic An. stephensi An. culicifacies - 0.008 ± 0.314 -0.970well An. stephensi - Cx. quinquefasciatus -0.060 ± 0.146 -An. stephensi - Cx. tritaeniorhynchus -0.093 ± 0.167 -An. culicifacies - Cx. quinquefasciatus 0.036 ± 0.377 -An. culicifacies - Cx. tritaeniorhynchus 0.75 ± 1.445 -Cx. tritaeniorhynchus - Cx. quinquefasciatus 0.012 ± 0.071 -0.860Bed Pools An. stephensi An. culicifacies 1.000 ± 0.393 -0.954An. stephensi - Cx. quinquefasciatus -0.833 ± 3.690 -An. stephensi - Cx. tritaeniorhynchus -0.970 ± 1.259 -An. culicifacies - Cx. quinquefasciatus 0.035 ± 0.079 -An. culicifacies - Cx. tritaeniorhynchus 0.737 ± 0.372 -Cx. tritaeniorhynchus - Cx. quinquefasciatus 0.461 ± 1.526 -0.848Puddles An. stephensi An. culicifacies -0.909 ± 2.795 -1.000An. stephensi - Cx. quinquefasciatus -0.923 ± 2.519 -An. stephensi - Cx. tritaeniorhynchus -1.000 ± 0.786 -An. culicifacies - Cx. quinquefasciatus -0.462 ± 0.64 -An. culicifacies - Cx. tritaeniorhynchus -0.420 ± 0.370 -Cx. tritaeniorhynchus - Cx. quinquefasciatus 0.180 ± 0.216 -0.505Hoof-Prints An. stephensi An. culicifacies 0.600 ± 3.561 -1.000An. stephensi - Cx. quinquefasciatus 0.818 ± 1.98 -An. stephensi - Cx. tritaeniorhynchus 0.111 ± 0.616 -An. culicifacies - Cx. quinquefasciatus 0.75 ± 1.591 -An. culicifacies - Cx. tritaeniorhynchus 0.938 ± 0.507 -Cx. tritaeniorhynchus - Cx. quinquefasciatus 0.205 ± 0.277 -0.762ABin Gujarat, An. culicifacies was positively associated surveyed. Intensive exploitation of rice fieldswith An. stephensi only in paddy fields (Bhatt et al., throughout the rice growing season for breeding by1990). Negative association was noticed in puddles, this species is a cause of concern. However, naturalwhich was also similar to present findings. Likewise, enforced intermittent irrigation due to acute waterin domestic wells a positive association existed shortage and withdrawal of rice cultivation maybetween An. culicifacies, Cx. quinquefasciatus and relatively contribute towards decreased risk inCx. tritaeniorhynchus. In puddles and hoof-prints, the outbreak of JE in this area. Investigations on mosquitocoexistence of vectors was relatively low.breeding in habitats in other extended areas mayprovide information on other species that may bePlanned and systematic extension of Chennai city isprevalent in areas adjoining the city. Due to theunderway resulting in rapid environmental changes.prevalence of disease factor and high labourBoth An. stephensi and An. culicifacies have beenmovement and activity, careful monitoring isobserved in extended regions of the city. An.indispensable for prevention of disease outbreaks.stephensi, responsible for intense malariaBioenvironmental control, found to be successful intransmission in Chennai dominated indicating speciesmany areas, can be planned and adopted in thisreplacement on account of environmental change. Cx.transition region before complete urbanization totritaeniorhynchus, among potential vectors of JE wasachieve effective species sanitation.ubiquitous and was found to breed in all habitats