Establishment of a focus on Anopheles fluviatilis, an important malaria vector near the National Thermal Power Corporation Project in Dadri CHC area in District Gautam Budh Nagar, Uttar Pradesh, India: a case study.

rural plain areas of India, where Anopheles culicifacies Giles (Diptera: Culicidae) is the primary malaria vector species. This species is responsible for about 60–65% of all reported malaria cases in India1 that breeds in irrigation channels, ponds, pools and rice fields. Anopheles fluviatilis James, is another important vector of malaria in India, which is found specifically in foothills and breeds in slow moving water in streams and channels. Various studies carried out in past in western Uttar Pradesh, India have reported An. culicifacies s.l. as the only established vector of malaria in this area2–3, whereas An. fluviatilis, has never been reported from this area. An. culicifacies s.l. is a complex of five sibling species4 out of which only two sibling species, viz. species A and species B are reported to be prevalent in this area. The area under Dadri Community Health Centre (CHC) in western Uttar Pradesh has remained highly endemic due to perennial breeding of An. culicifacies in the seepage water from irrigation channels of the Upper Ganga Canal. During 1980’s a new project of the National Thermal Power Corporation (NTPC) was setup in this area to meet the demand for power supply in the National Capital Region without the health impact assessment. While carrying out a field survey in Dadri CHC area, we noticed the presence of An. fluviatilis in high densities for the first time during November 2009. In the present study, we report the establishment of a new focus of An. fluviatilis in the area and possible repercussion in connection with malaria transmission. Dadri CHC area of District Gautam Budh Nagar in Uttar Pradesh (9° 72′N and 80° 28′E) is located at a distance of about 40–45 km from Delhi. The weather conditions can be divided into four seasons, summer (March– June), monsoon (July–August), autumn (September– October) and winter (November–February). The maximum temperature during summer months goes up to >46°C and the minimum temperature during winter in the month of January falls to <4°C. An entomological survey was carried out in different villages of Dadri CHC during the months of October– November 2009, which revealed the prevalence of An. fluviatilis s.l. in some villages of Dadri CHC. All the villages (Fig. 1), from where An. fluviatilis were collected are located adjacent to a canal, which carries the discharged water from NTPC plant along with surplus water from the tributary of the Upper Ganga Canal. The density of An. fluviatilis in this area was regularly monitored in six representative villages located adjacent to NTPC canal, where An. fluviatilis was detected for the first time in the month of November 2009. Indoor resting adult mosquitoes were collected at monthly intervals up to September 2012. Adult anopheline mosquitoes were collected from four fixed and four randomly selected human dwellings and cattlesheds by hand catch method using a flashlight and an aspirator during the morning hours and transported in thermocol box to our laboratory for further analysis. In addition to the indoor resting adult mosquito collection, anopheline larvae were also collected periodically from NTPC canal and from other larval habitats in the area and brought to the laboratory and reared up to adult stage in the insectary. The emerged adults were identified both morphologically and by molecular method for reconfirmation of species. All the adult mosquitoes were identified morphologically using standard identification key5. Morphologically identified An. culicifacies and An. fluviatilis were further processed for the sibling species composition by cytotaxonomy and DNA sequence6–8. Cytolological identification of An. culicifacies and An. fluviatilis sibling species was carried out by examining the ovarian polytene chromosomes for species-specific diagnostic inversions for the identification of the J Vector Borne Dis 50, December 2013, pp. 307–310