ASSESSMENT OF PUPAL PRODUCTIVITY OF AEDES AND CO-OCCURRING MOSQUITOES IN KOLKATA, INDIA.

Monitoring of dengue vectors provide baseline information about the abundance and subsequent management strategy. An appraisal of mosquito abundance using dengue vectors as focal species was made in respect to Kolkata, India as geographical area. The data on immature abundance in the container larval habitats viz, earthen, porcelain and plastic materials were subjected to three-way factorial ANOVA, using months, habitats and species as variables. Similar tests were done on pupal weight and wing length. It was observed that Anopheles subpictus, Culex quinquefasciatus coexist with Ae. aegypti and Ae. albopictus in different container habitats, that varied with months and habitats. Ae. aegypti and Ae. albopictus were found in higher proportions in porcelain and plastic containers. In earthen containers a stable ratio of three mosquitoes was observed. Sex specific variations in pupal weight and wing length were noted in both species of Ae. aegypti and Ae. albopictus. The wing length of adult Aedes mosquitoes showed correspondence with pupal weight suggesting the use of pupal weight can be used as indicator of prospective adult body size. Although less known as container breeding, presence of An. subpictus and Cx. quinquefascistus along with Aedes indicates that availability of waste containers in environment increases risks of dengue and other mosquito borne diseases. The present habitat-based study calls for a strict vector management strategy to reduce the sources of ovipostion in various container habitats to minimize the mosquito vectors and thus potential risk of dengue and other mosquito borne diseases.

An assessment of macroinvertebrate assemblages in mosquito larval habitats--space and diversity relationship.

The aquatic bodies designated as mosquito larval habitats are diverse in size and species composition. The macroinvertebrate predators in these habitats are elements that influence the abundance of mosquito species, providing a basis for biological control. Assessment of species assemblage in these habitats will indicate the possible variations in the resource exploitation and trophic interactions and, therefore, can help to frame biological control strategies more appropriately. In the present study, the species composition is being investigated in five different mosquito larval habitats at a spatial scale. A random sample of 80 each of the habitats, grouped as either small or large, was analyzed in respect to the macroinvertebrate species assemblage. The species composition in the habitats was noted to be an increasing function of habitat size (species number = 1.653 + 0.819 habitat size) and, thus, the diversity. The relative abundance of the mosquito immatures varied with the habitat, and the number of useful predator taxa was higher in the larger habitats. In the smaller habitats-plastic and earthen structures and sewage drains, the relative and absolute number of mosquito immatures per sampling unit were significantly higher than the pond and rice field habitats. This was evident in the cluster analysis where the smaller habitats were more related than the larger habitats. The principal component analysis on the species diversity yielded four and six components, respectively, for the smaller and larger habitats for explaining the observed variance of species abundance. The species composition in the habitats was consistent with the earlier findings and support that the abundance of coexisting macroinvertebrate species regulates the relative load of mosquito immatures in the habitats. The findings of this study may be further tested to deduce the relative importance of the habitats in terms of the productivity of mosquito immatures at a temporal scale.