© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1434-2944/07/306-242 NABANEETA SAHA 1, 2 , GAUTAM ADITYA 1, 3 , ANIMESH BAL 2 and GOUTAM KUMAR SAHA* , 1 1 Department of Zoology, University of Calcutta, 35, Ballygunge Circular Road, Kolkata 700019. India; e-mail: nabaneetasaha@gmail.com 2 Zoological Survey of India, M Block, New Alipore, Kolkata 700053. India 3 Department of Zoology, The University of Burdwan, Golapbag, Burdwan 713104. India Comparative Study of Functional Response of Common Hemipteran Bugs of East Calcutta Wetlands, India key words: mutual interference, Anisops bouvieri, Diplonychus rusticus, D. annulatus, Culex quinquefasciatus, larvae Abstract The common and abundant hemipteran water bugs Anisops bouvieri, Diplonychus rusticus, D. annu- latus, of the wetlands of East Kolkata are known predators of a wide range of aquatic insects including the mosquito larvae. In the laboratory their predation were assessed in respect to short term and long term periods using the larvae of Culex quinquefasciatus to reveal their possible role in regulating the dipteran population in nature. The attack rate (a) and handling time (T h ) of these predators varied with respect to the prey size. For the backswimmers A. bouvieri the values for a and T h for the small prey were 5.47 L and 18.72 min respectively, while in case of the belostomatid bugs, the values for the same were 5.37 L and 8.64 min (for D. rusticus), 5.81 L and 20.16 min (for D. annulatus). The predation rate varied with prey and predator densities for both the prey sizes. It was revealed that on an average A. bou- vieri can kill and consume 10–82 and 6 – 44, D. rusticus 10–118 and 10 –84 and D. annulatus 10–70 and 10–138 small and large sized prey per day, respectively. However the mutual interference (m) values of the three predators varied with the prey size and ranged between 0.053–0.326 for A. bouvieri, 0.0381– 0.066 for D. rusticus and 0.0556– 0.115 for D. annulatus, respectively. In the long term exper- iments A. bouvieri killed between 6 –119 small preys and 3–31 large preys, D. rusticus killed 50 –94 small preys and 50 –96 large preys and D. annulatum were found to kill between 14–74 small prey and 50 –131 large prey per day, respectively. The clearance rates were found to be proportional to the preda- tor density as well to the prey size and density, and differed between the predator species significant- ly. These data are supportive of qualifying the water bugs, A. bouvieri, D. rusticus, and D. annulatus as potential biological resources in regulating the population of mosquito larvae in the wet- lands. 1. Introduction The eastern fringe of the city of Kolkata is characterized by the perennial East Calcutta wetlands already incorporated in the list of Ramsar. Certain portions are commercially exploited for sewage fed fisheries and prawn cultures. The rest of the wetlands is free from human interference and hosts a greater amount of biodiversity compared to similar wetlands in the state. Fragmentary records of different species inhabiting these wetlands suggest that insect diversity at both taxonomic and ecological level is very high (IWMED, 2004). This includes dipterans like mosquitoes and chironomids and the Hemipterans, particularly the belostomatids and the notonectids (NANDI et al., 1993; KHAN and GHOSH, 2001). Controph- ic chironomid and the mosquito larvae share the belostomatids and notonectids as predators Internat. Rev. Hydrobiol. 92 2007 3 242–257 DOI: 10.1002/iroh.200610939 * Corresponding author