Distribution of Dengue Vectors during Pre- and Post-Monsoon Seasons in Higher Attitudes of Nilgiri Hills of Western Ghats, India

Entomological survey was carried out to record dengue vectors during pre- and post-monsoon seasons in 2012 from different breeding places in residential and forested areas of different altitudes of the Nilgiris, namely, Mettupalayam (330？mts), Kallar (400？mts), Burliar (900？mts), Marapalam (1050？mts), and Coonoor (1800？mts). Results showed that maximum number of dengue vector breeding was recorded at Mettupalayam during pre-monsoon season followed by Kallar, Burliar, Coonoor, and Marapalam. The post-monsoon season survey also revealed that the maximum number of dengue vector breeding was found at Mettupalayam, followed by Burliar, Coonoor, and Kallar, and Aedes immature was not found in Marapalam. Ae. aegypti species was recorded in all the study areas during pre- and post-monsoon seasons. Whereas Ae. albopictus was recorded only at Mettupalayam, Kallar, and Burliar during pre- and post-monsoon seasons. Besides these two dengue vectors, a nonvector species Ae. vittatus ( ) was also recorded at Kallar and Burliar. 1. Introduction Studies on taxonomy, biology, distribution, and ecology of haematophagous arthropods are of public importance. General reviews of the ecology and control of individual vector groups should be continued and revised from time to time to provide workers with update status [1]. Mosquitoes are haematophagous insects in terms of public health significance and they are remarkably adapted to coexist with man and domestic animals. There are 3490 species of mosquitoes recorded so far worldwide [2], among them, more than 100 species are recorded as vectors transmitting various diseases [3]. Increasing population, unplanned organization, rapid transportation, unreliable water supplies, and water storage practices of peoples are results in the rapid spreading of mosquito species [4]. The Nilgiri hills located in Tamil Nadu of south India are highly diverse in terms of ecology and culture. The terrain features and climatic conditions like temperature, humidity, rainfall, the forest cover, and availability of breeding habitats render the area suitable for the existence of mosquitoes [5]. Rahman et al. [6] had done an intensive survey and reported the presence of 52 mosquito species in the Nilgiris. Balakrishnan et al. [5] reported the presence of Aedes aegypti mosquitoes in the Nilgiris and its adjoining areas with special reference to dengue fever survey. In view of uncertainty of the present remedial measures, a thorough study of human-environmental interrelation, climate wise distribution, and changing pattern of occupancy according to