Aquatic Insect Inventory Of A Stream Of Chakrashila Wildlife Sanctuary, Btc Area, Western Assam, India A Seasonal Study.

Introduction: What conservation problem or question does your study address?
Studies on the aquatic insect fauna of north-eastern part of India are mainly from lentic systems with a very few on lotic systems. Here we present seasonal variation of aquatic insect diversity of Jornagra stream of Chakrashila Wildlife Sanctuary (CWS), situated in the biodiversity hotspot, Himalaya. The sanctuary is the second home of Golden Langur, occurring only in the foothills of Himalaya. No study on the aquatic insects of the streams of this area is done.

Methods: What were the main research methods you used?
Insect samples were collected seasonally in replicates from different stretches (260 17/ to 260 21/ N and 900 17/ to 900 20/ E) of Jornagra stream of the Sanctuary by “all out search” method, nylon pond net method (Subramanian & Sivaramakrishnan 2007) and 1 minute kick method (Brittain 1974) during 2012. They were sorted, preserved in 70% alcohol, observed under under different stereoscopic microscopes (Magnus, Model- MSZ-TR; Motic, Model- SMZ-168). and identified with the help of standard keys descriptions (Webb and Suter 2001;Thirumalai 2002;Jessup et al. 2003; Niesser 2004; Miller 2005;Braasch 2006;Epler 2006; Bouchard 2009). Water from the same stretches of the stream were collected and analyzed by the standard methods (Michael, 1984; Trimmer, 1994; APHA, 2005).

Results: What are your most important results?
A total of 8 species of aquatic insects belonging to 3 orders was recorded. The number of species found in different seasons was: Pre-monsoon=3, Monsoon=5, Post-monsoon=6, and Winter=6. Hemiptera was the most abundant order in all the seasons.Ptilomera assamensis, Metrocoris nigrofashioides, Rhagovelia obesa had a widespread distribution throughout the year. The environmental variables of the stream were within the permissible limit (BIS, 2010 and WHO, 2011).

Discussion: What are your important discussion points and what is the relevance of your results to conservation (if any)?
This study revealed a thorough investigation of aquatic insects of Jornagra stream of CWS. The dominance of Hemiptera in the tropical water bodies has been shown by several workers from India. The environmental variable analysis showed a good water quality. But with respect of water quality a more number of species was expected, these less number of species may be due to entrance of anthropogenic impact. We recommend conservation program around the area of the Sanctuary.