Research Journal of Recent Sciences _________________________________________________ ISSN 2277-2502 Vol. 4(ISC-2014), 308-312 (2015) Res. J. Recent. Sci. International Science Congress Association 308 Diversity and Population Turnover of Insect Fauna in Pushkar Lake in the Aravalli Region of Rajasthan, India Tak A.S. and Srivastava D. Govt. Dungar College, Bikaner, INDIAAvailable online at: www.isca.in, www.isca.me Received 17th November 2015, revised 21st March 2015, accepted 17th May 2015 Abstract Anthropogenic pressures, holy rituals and tourism have adverse impact on the water quality of the sacred lakes. Physico-chemical parameters are directly affecting to diversity of insect fauna of the water bodies. The present communication deals with the year round study on of insect fauna and its ecological aspects in the Pushkar lake, Ajmer from April, 2012 to March, 2013. Physical-chemical limnology revealed that the lake was shallow with turbid, alkaline, hard, slightly saline and well oxygenated water. The adult insect fauna displayed a diversity of 18 species belonging to families namely Dytiscidae (4), Helodidae (1), Hydraenidae (1), Hydrophilidae (4), Psephenidae (1), Corixidae (1), Gerriidae (2), Nepidae (2), Notonectidae (1) and Velidae (1) besides the larval forms of aquatic and terrestrial insect. The data on population turnover and periodicity of occurrence is viewed upon to adjudge the sensitivity of species to environmental condition. Keywords: Aquatic insects, Physical-chemical limnology, Sacred lake, Diversity, Population turnover. Introduction The aquatic insects including their larvae are involved in nutrient recycling and form an important vital component of natural food web in aquatic ecosystem. Aquatic macro-invertebrates have been identified as excellent tool for bio monitoring studies as they respond rapidly to the environmental changes. Their abundance, diversity and short life cycle makes them ideal subjects for the assessment of wetland's ecological conditionsAquatic insects play an important role in the indication of the changes in the quality of water due to pollution or degradation because of their ability to respond quickly to such alterations. Freshwater insects may be used to assess the “health” of a water body. Physico-chemical parameters are directly affecting to diversity of insect fauna of the water bodies. Anthropogenic pressures, holy rituals and tourism have adverse impact on the water quality of the sacred lakes. Tourism industry is a major contributor to the gross national product of many nations Pushkar is a famous pilgrimage centre of Rajasthan. In the ancient times the lake had water spread over 71 bighas. However, of late, Pushkar lake is dying due to a variety of reasons. On an average the lake attracts 5000 pilgrims daily. People from all over the country converge here to wash off their sins and immerse the ashes of their dead. The ecosystem process of the lake has been altered and has resulted in loss of biodiversity, eutrophication, siltation and toxic contamination over the years. Lakes are closed ecosystems and hence pollution tends to accumulate in the lake body. High pollution and silting of the lake are causes of serious concern. Congestion of areas in and around the lake have restricted the natural drainage into the lake. Water quality in the lake has been deteriorating continuously primarily due to uncontrolled flow of sewage and waste water and disposal of solid waste in the catchment drains. Regular offerings of flower and bone ash have caused the water quality to deteriorate further. Over the past two decades the water level has been going down continuously. However tube wells are installed near the periphery to maintain the water level and in turn the lake harbour wide range of flora and fauna and thus need to be conserved. The present study was undertaken on Pushkar lake, Ajmer from April, 2012 to March, 2013. The data on population density are viewed upon to adjudge the sensitivity of insect species to environmental conditions. Material and Methods Study Area: Pushkar is situated 14kms on the North west of Ajmer. The geographical coordinates are 26°30°0” North 74°33’0” East. The Pushkar lake draws catchment of the Aravalli hills covering an area of 22 Sq. Kilometers. The lake has water surface of 22 hectares. Both water and sediment samples were collected from three study stations. i. The insect fauna from water was collected with suitable nets covering both macroscopic and microscopic forms. A quadrate was used to collect the samples of sandy sediment. Benthic forms were collected by sieving the mud samples. The results are expressed in the No. / m2 . ii. Population turnover was calculated as Maximum population/ Minimum population recorded. iii. Water was Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 4(ISC-2014), 308-312 (2015) Res. J. Recent. Sci. International Science Congress Association 309 examined for major ecological variables including temperature, pH, electrical conductance, total dissolved solids, dissolved gases (oxygen, carbon dioxide), alkalinity and hardness. The sediment samples were examined for pH, electrical conductance, total dissolved solids and organic matter. The analysis was made following APHA-AWWA-WPCF. For parameters like temperature, pH, electrical conductance and total dissolved solids, respective meters were used. iv. Insect fauna were identified following Daglish (1952), Borrer and Delong (1957), Edmondson (1966), Needham and Needham (1978), Tonapi (1980) and Mc Cafferty (1981)6-11. Results and Discussion Physical-chemical limnology revealed that the lake was shallow with turbid, alkaline, hard, slightly saline and well oxygenated water. The ranges of important abiotic variables of water were observed as Temperature 17.8 – 32.8ºC, transparency 0.4-0.5m, pH 7.3 - 8.0, EC 0.31- 0.42 mmho/ cm, DO 8.53 - 19.10 mg/l, Free CO 2 - 78 mg/l, TDS 320-420 mg/l, Hardness 112 - 184 mg/l and total alkalinity 38 - 104 mg/l. Sediment analysis revealed the ranges of values as pH 8.8 – 10.3, EC 0.26 - 0.43 mmho/ cm, TDS 260 - 430 mg/g and Organic matter 22.27 – 69.26 mg/g (table 1). Most of the major orders of insects are found in the Indian desert and many of them present interesting adaptations to the desert environment12. Insects, the most versatile and tolerant group of invertebrates, are especially important faunal component in desert waters, most of which are ephemeral and offer extremely hostile physical and chemical conditions. In spite of the fact that insects are no lesser important denizens of aquatic environment, no sincere efforts seem to have been made on aquatic insects of the desert region of Rajasthan, except the contributions of Vazirani (1964), Tak and Sewak (1987), Tak (1996), Srivastava and Saxena (2004), Saxena (2008) and Srivastava (2009)13-18. During the present study insects were represented by adult as well as larval forms. The adult insect fauna belonged to only two orders namely Coleoptera (beetles) and Hemiptera (bugs). Coleoptera was represented by five families namely Dytiscidae (4Species), Helodidae (1), Hydraenidae (1), Hydrophilidae (4) and Psephenidae (1). Hemiptera was also represented by five families Corixidae (1), Gerriidae (2), Nepidae (2), Notonectidae (1) and Veliidae (1) in the lake. Apart from these orders Diptera (Mosquitoes, Flies, and Midges), Ephemeroptera (Mayfly larva), Odonata (Dragonflies) and Plecoptera (Stoneflies) were represented only by larval forms. The beetles dominated the bugs in the lake except in the months of July and August because of the rise in the population of Water striders due to rains. More over the population of beetles were far below than their average population i.e. 851.66 during these two months. Temperature of the lake water, lower than the average value (25.45C) supported the population of Coleoptera to flourish. The population of Hemiptera was recorded better with the higher values of temperature than the average one. Numerically Hydraticus fabricii was the most abundant species followed by Hydraena quadricoliis (Table-2 and figure-1). The only perennial forms were chironomid larvae of order Diptera and nymphs of Odonata while other species occurred only for 8 to 10 months in the year. Hydaticus fabricii presented the widest range of population fluctuation over the period of study as reflected from its greater population turnover followed by Hydraena quadricollis, Tropisternus lateralis, Dytiscus verticalis, Berosus Sp. and Corixa lima. Scirtes nigropunctatus, Limnometra fluviorum and Notonecta glaucaexhibited poor population turnover with poor periodicity. The rest of the species displayed a lesser population turnover suggesting narrow variation in their count during the period of study. The greater population turnover of a species suggests the greater sensitivity of it to the available environmental conditions of existence. However, this should be viewed upon with the incorporation of data on the periodicity of occurrence of the individual species. Thus a species may, however be having a poor population turnover, if displays poor periodicity, is obviously highly sensitive to the available environmental conditions during most part of the year19. It is important to note that even when the insect population was less, the number of chironomid larvae was good enough to indicate the pollution in the lake as it can live in highly polluted waters. Conclusion The sacred lake of Pushkar was shallow with turbid, alkaline, hard, slightly saline and well oxygenated water. The lake harboured 18 species of Insects (Adult) belonging to two order Coleoptera (beetles) and Hemiptera (bugs) displaying 5 families each besides the larval forms of aquatic and terrestrial insects. The beetles dominated the bugs both in the term of diversity (11:7 species) and population density (79%: 21%) because of their anatomical and physiological features and feeding habits. In order to conserve the Insect and over all faunal diversity of such stressed sacred lakes it is essential to ensure perennially available economically safe water, which could be achieved by judicious water utilization, proper watershed area management and upkeep of water quality. Social rituals can’t be redefined but have to be managed. Acknowledgement Authors are thankful to the Govt. Dungar College, Bikaner for providing necessary facilities. Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 4(ISC-2014), 308-312 (2015) Res. J. Recent. Sci. International Science Congress Association 310  \n \r\n\r     \n \n!  \n !  \n"!!Figure-1 Total insects at the lake of Pushkar Lake, Ajmer during April, 2012 to March, 2013. Values are averages of three study station and are expressed as No/mTable-1 Physical-chemical variables at Pushkar lake, Ajmer during April, 2012-March, 2013. Values are averages of three study stations and are expressed in mg/l in water and mg/g in sediment, except otherwise mentioned. Variable Apr 2012 May 2012 June 2012 July 2012 Aug 2012 Sept 2012 Oct 2012 Nov 2012 Dec 2012 Jan 2013 Feb 2013 Mar 2013 Avg. Water Temperature (ºC) 26.2 27.2 31.6 32.5 32.3 25.2 24.4 23.2 22.1 17.8 20.4 22.6 25.45 Transparency (m) 0.5 0.5 0.4 0.4 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.48 pH 7.3 7.6 7.8 8.0 7.6 7.8 7.4 7.6 7.5 7.4 7.3 7.4 7.55 EC (mmho/cm) 0.37 0.34 0.38 0.36 0.39 0.38 0.34 0.41 0.42 0.36 0.39 0.34 0.37 DO 17.07 18.69 15.85 11.38 14.63 19.1 9.76 12.6 8.53 8.94 12.6 15.45 13.72 Free CO78 44 34 36 48 32 12 2 4 38 46 12 38.83 TDS 370 340 380 360 390 380 340 410 420 360 390 340 373.33 Hardness 146 172 184 166 162 112 126 136 144 184 158 126 151.33 Total Alkalinity 52 68 104 76 62 46 38 66 42 76 62 38 60.83 Sediment pH 9.3 8.9 10.0 9.8 10.2 8.7 9.4 9.2 8.8 9.8 9.3 9.7 9.42 EC (mmho/cm) 0.39 0.37 0.42 0.34 0.43 0.36 0.38 0.39 0.41 0.34 0.26 0.38 0.37 TDS 390 370 420 340 430 360 380 390 410 340 260 380 372.5 Organic matter 54.32 48.88 39.51 64.36 44.54 66.54 22.27 29.87 17.38 22.27 66.81 69.26 45.50 Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 4(ISC-2014), 308-312 (2015) Res. J. Recent. Sci. International Science Congress Association 311 Table-2 Diversity and population density of Insect fauna at Pushkar Lake, Ajmer during April, 2012 – March, 2013 Values are averages of three study stations and are expressed as No./m. Insect species Apr 2012 May 2012 June 2012 July 2012 Aug 2012 Sept 2012 Oct 2012 Nov 2012 Dec 2012 Jan 2013 Feb 2013 Mar 2013 Avg. Population Turnover Max. Pop./ Min. Pop. Periodicity of Occurrence O-COLEOPTERA ( Beetle ) F- DYTISCIDAE ( Predaceous Diving Beetle ) Captotomus enterrogatus 00 00 00 00 00 60 100 80 100 100 140 140 60 2.33 7 Dytiscus verticalis 00 00 40 00 00 00 40 60 100 220 100 80 53.33 5.50 7 Hydaticus fabricii 00 60 80 60 100 80 00 380 560 480 540 480 235 9.33 10 Laccophilus anticatus 80 00 00 00 00 00 60 80 80 100 140 80 51.66 2.33 7 F-HELODIDAE ( Marsh Beetle ) Scirtes nigropunctatus 00 00 00 00 00 00 00 80 60 00 00 00 11.66 1.33 2 F-HYDRAENIDAE ( Minute Moss Beetle) Hydraena quadricollis 360 240 120 00 00 00 00 00 00 800 580 280 195.33 6.66 6 F- HYDROPHILIDAE ( Water Scavenger Beetle ) Berosus sp. 120 320 180 00 00 60 00 00 00 00 00 00 56.66 5.33 4 Enochrus sp. 00 00 00 00 00 00 60 100 60 60 100 100 40 2.5 6 Hydrophilus olivaceous 00 00 00 80 60 40 00 60 00 00 00 00 20 2.0 4 Tropisternus lateralis 00 00 00 00 00 80 80 60 40 240 180 80 63.33 6.0 7 F- PSEPHENIDAE ( Riffle Beetle ) Eubranax sp. 00 00 00 00 00 00 120 180 100 140 100 100 61.66 1.8 6 Total Beetles 560 620 420 140 160 320 460 1080 1100 2140 1880 1340 851.66 15.28 12 O-HEMIPTERA ( Bugs ) F- CORIXIDAE ( Water Boatman ) Corixa lima 200 80 60 80 60 40 00 60 00 00 00 00 46.33 5.00 7 F- GERRIDAE ( Water Striders ) Gerris marginatus 80 00 80 160 140 100 100 00 00 00 00 80 61.66 2.00 7 Limnometra fluviorum 00 00 00 80 100 80 00 00 00 00 00 00 21.66 1.25 3 F-NOTONECTIDAE ( Backswimmers ) Notonecta glauca 00 00 00 00 00 00 00 00 00 80 40 00 10 2.0 2 F- NEPIDAE ( Water Scorpion) Laccotrepes maculatus00 80 60 00 40 00 00 80 40 100 120 00 43.33 3.0 7 Nepa cineria20 80 00 00 00 00 20 40 60 80 60 20 31.66 4.0 8 F- VELIIDAE ( Riffle Bugs) Microvelia diluta 00 00 40 60 00 40 60 00 00 00 00 00 18.33 1.5 4 Total Bugs 300 240 240 380 340 260 180 180 100 260 220 100 233.33 3.8 12 Total Insects 560 860 860 520 500 580 640 1260 1200 2400 2100 1440 1076.33 4.80 12 References 1.Rader R.B., Batzer D.P. and Wissinger S.A., Bioassessment and Management of North American Freshwater Wetlands, John Wiley and Sons, New York, (2001) 2.Riege A.M. and Perry C., National marketing Strategies in international travel and tourism, European Journal of marketing. 34 (11/12), 1290-1305 (2000) 3.Jain S.K., Agarwal P.K. and Singh V.P., Hydrology and Water Resources of India, Water Sci. 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