Ovitrap Surveillance of Aedes Mosquitoes (Diptera: Culicidae) in Selected Areas of Dehradun District, Uttarakhand, India

Abstract

Background & Objective : Dengue, a major public health problem in India is caused mainly by Aedes aegypti and Ae. albopictus. In Uttarakhand State (India), there has been a heavy increase in dengue cases in the year 2010 and thereafter in 2011-12, there was a decline. Keeping in view a change in climatic scenario i.e., heavy rainfall during June to September, we are expecting more and more cases of dengue this year too. Since there is lack of information on the bionomics of the recognized vectors of dengue from this region, it has been planned to determine the efficacy of ovitraps in monitoring the distribution and abundance of Aedes species in different urban and suburban areas of district Dehradun, Uttarakhand. Methods: Ovitraps were placed at three sites viz., Sahastradhara, Garhi Cantt. and Karanpur of Dehradun city during August 2012 - July 2013 and examined weekly. Collected paddles were submerged into a bowl of water containing larval food. The hatched larvae were subsequently counted and reared in the cages to emerge into adults and identified upto species level using respective Keys and Catalogues. The estimation of ovitrap indices was done following the protocol developed by FEHD. and Lim et al.(2010) Result: As many as 6 species of Aedes viz., Aedes aegypti, Ae. albopictus, Ae. edwardsi, Ae. pseudotaeniatus, Ae. unilineatus and Ae. vitattus were collected during the study period. Ae. aegypti shared highest (37.28%) followed by Ae. albopictus (33.27%), Ae. pseudotaeniatus, (15.68%) and Ae. vitattus (8.33%). The mixed breeding comprised larvae of Culex, Anopheles and some unidentified species and shared least percentage (3.10%). In indoor, overall mosquito accounts low percentage (18.82%) in all three localities as compared to outdoor percentage (19.47%). Maximum ovitrap index was encountered from Garhi Cantt. (48.75) followed by Karanpur (45.00) and Sahastradhara (43.75) during August 2012. Outdoor indices of area ovitraps index were in the range of 17.30±1.83 to 21.88±2.10, while in indoors the range was 12.30±1.67 to 15.42±1.56. Monthy ovitrap index of the study period ranged from 0.00 to 45.83. Conclusion: Ovitraps provide a very sensitive and economical method for detecting container breeders when the population density is low. A high density of dengue vectors in the residential area warrants the vector surveillance activities in time along with awareness programme.