arunkumar shetty department of p.g. studies and research in applied zoology, kuvempu university, shankaraghatta, 577 451 karnataka. mididodi venkateshwarlu department of p.g. studies and research in applied zoology, kuvempu university, shankaraghatta, 577 451. karnataka. murugan muralidharan sri paramakalyani centre for environmental scieces, manonmaniam sundaranar university, alwarkurichi, 627 412. tamilnadu