OCCASIONAL PAPER NO. 194 RECORDS OF THE ZOOLOGICAL SURVEY OF INDIA Faunal Diversity of Aquatic Insects in Freshwater Wedands of South Eastern West Bengal R.A. KHAN L.K. GHOSH ZOOLOGICAL SURVEY OF INDIA OCCASIONAL PAPER NO. 194 RECORDS OF THE ZOOLOGICAL SURVEY OF INDIA Faunal Diversity of Aquatic Insects in Freshwater Wetlands of South Eastern West Bengal .R. A. KHAN and L. K. GHOSH Zoological Survey of India, 234/4 A. J C. Bose Road, Nizam Palace, Kolkata-700020 Edited by the Director, Zoological Survey of India, Kolkata.. ZoolOgical Survey of India Kolkata CITATION Khan, R. A. and Ghosh, L. K. 2001. Fnunal Diversity of Aquatic Insects in Freshwater Wetlands of South Eastern West Bengnl, Rec. zool Surv. India, Occ. Paper No. 194 : 1-104· (Published - Director, Zool. SUlV. India, Kolkata). Published : December, 2001 ISBN : 81-85874-74-3 © Government of India, 2001 ALL RIGHTS RESERVED • No Part of this publication may be reproduced stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior permission of the publisher. • This book is sold subiect to the condition that it shall not, by way of trade, be lent, resold hired out or otherwise disposed of without the publisher's consent, in any form of bi!lding or cover other than that in which, it is published. • The correct price of this publication is the price printed on this page. ·Any revised price indicated by a rubber stamp or by a sticker or by any other means is incorrect and should be unacceptable. PRICE Indian : Rs. 150.00 Foreign: $ 10 £ 7 Published at the Publication Division by the Director, Zoological Survey of India, 234/4, AJe Bose Road, 2nd MSO Building (13th Floor), Nizam Palace, Calcutta-700 020 and printed at Krishna Printing Works, Kolkata-700006. RECORDS OF THE ZOOLOGICAL SURVEY OF INDIA OCCASIONAL PAPER No. 194 2001 Pages 1-104 CONTENTS Ina-oduction .............................................................................................................................. ... ... 1 Material and Metllods ................................................................................................................... 3 Results ......................................................................................................................... It ••••••••••••••••••• 5 Physico-chemical parameters of water quality ...................................................................... .5 Macrophytes ............................................................................................................................. 6 Diversity of insect fauna ................................................................................................................ 6 Ephemeroptera ................................................................................................................................ 9 Systematic list ......................................................................................................................... 10 Systematic account ................................................................................................................ 10 Odonata .............................. , .......................................................................................................... 14 Systematic list ......................................................................................................................... 16 Hemi ptera ...................................................................................................................................... 28 Systematic list of Aquatic and semi-aquatic insects ............................................................... 29 Coleoptera ......................................................................................................................................j 1 Systematic list of Taxa .......................................................................................................... 51 Total density -a relative composition of different insect groups ......................................... 79 AbundaIlt species ......................................................................................................................... 8() Diversity species ............................................................................................................................ 80 Similarity between wetlands ........................................................................................................ 80 Discussion , ............ ,........... , .......... ,................................................................................................. 8~ Summ 8l"}' ................................................................................................................................. .. 84 Acknowledgements ....................................................................................................................... 85 References ...................................................................................................................................... 85 INTRODUCTION Among various biological components of freshwaters, the aquatic insects play an important role not only in the trophic dynamics of the ecosystem but also in the indication of changes in tlle quality of water due to pollution or degradation because of their ability to respond qUickly to such changes. While most of the aquatic insect species constitute the food of many commercially important fishes, some others are predaceous, feeding upon spawn and frys or competing with them directly for natural food. Besides, several species, particularly of Belostomatid Hemi ptera are known to predate heavily upon the mosquito larvae and thereby limiting their population size. Eventhough the insects are terrestrial in origin, a large number of species belonging to several orders have adapted to aquatic mode of life completely or partially. It is estimated that about 3% of the total insects are aquatic, spending atleast a part of their life cycles in the water, and these comprise about 25,000 to 30,000 species (Cheng, 1976) .The highly diverse aquatic forms are spread over to 11 orders viz. Collembola, Plecoptera, Ephemeroptera, Odonata, Hemi ptera, Megaloptera Neuroptera, Trichoptera, Lepidoptera, Coleoptera and Di ptera. Out of these, taxa belonging to only a few groups like Ephemeroptera, Odonata, Hemi ptera ,Coleoptera and Di ptera form the dominant component of fauna of the freshwater wetlands of this region. The Orders Trichoptera, Plecoptera, Neuroptera and majority of the aquatic species of Ephemeroptera are mainly confined to high altitudes or colder climate. The taxonomy of the aquatic insects is not as properly worked out as those of their terrestrial counterparts because of difficulties in the identification of immature forms. Most of the aquatic insects pass their early part of life in water in immature condition and sometimes the immature duration covers major part of their life cycles. However, the taxonomy .based on adults have fairly been worked out, particularly those belonging to temperate waters (Pennak, 1978; Ushinger, 1971). In India, while a few earlier workers dealt with the taxonomy of aquatic insects of the country, mostly along with terrestrial members of the group dealt (Distant, 1902, 1906, 1910; d'Orchymont, 1925, 1928; Ochs, 1930; Vazirani, 1968, 1970), their works remained almost scattered. Recently, faunal account of the species occuning in the region has been consolidated (Srivnsatva, 1993 on Ephemeroptera; Srivastava & Sinha 19P3 on Odonata; Bal and Basu, 1994a, 1994b on Hemi ptera; Biswas et al. 1995a, 1995b, Biswas and Mukhopadhyay, 1995 on Coleoptera, and Choudhury and Chattopadhyay, 1997 on Diptera) but these studies too remained confmed to pure museum taxonomy and also included those species which were described by earlier workers but could not be observed/collected during last few de~ From ecolOgical pOint of view, very little attention has been paid and IP~ ~ the ~dies 2 . Rcc. zool. Surv. India~ Oce. Paper No. 194 o o C\J ('i) C\J C\I -89 \ , \ " \ l 87 • • KHAN and GHOSH: Faunal Diversity ojAquatic Insects ... Eastern fVest Bengal 3 on limnolgy / aquatic biology of freshwater wetlands either completely ignore this component or give simply a passing reference. This is practically due to non-availability of any consolidated document dealing with the identification and ecology of commonly occurring insects of freshwaters wetlands of the country. The few studies, which deal with speCific groups of aquatic insects, are those of Tonapi, (1959) and Tonapi and Ozarkar (1969a, 1969b) on Coleoptera and Alfred (1973) on Di ptera: Chronomidae. Limited number of studies has also been carried out on general entomofauna of some specific wetlands from taxa-ecolOgical viewpoints which includes the works of Roy, 1982, Roy and Sharma, (1983) Roy et al., (1988), De (Pal) and Sengupta (1993), Bhattacharya (2000)· and Pal et ru. (2000). Realizing the importance of the group and general dearth of knowledge, the present studies were carried out during last 10 years (1991-2000) with a viewpOint to work out the commonly occurring insect fauna of different types of wetlands of South-eastern region of West Bengal State. Their occurrence and abundance in a large number of wetlands belonging to different types, identification keys, descri ption of diagnostic characters, disnibution and general remarks on their ecology have been dealt with. It may