Journal of Entomological and Acarological Research 2014; volume 46:1977

Influence of density on intraguild predation of aquatic (Heteroptera): implications in biological control of S. Brahma,1 G. Aditya,1,2 D. Sharma,1 N. Saha,1 M. Kundu,2 G.K. Saha1 1Department of Zoology, University of Calcutta, Kolkata; 2Department of Zoology, The University of Burdwan, Golapbag, India

increased with the density of IG predator, in IGP system. Increase in den- Abstract sity of mosquito and D. rusticus enhanced risk to predation of mosquito while reducing the mortality of A. bouvieri. Interaction between D. rus- The water bugs Diplonychus rusticus (Fabricius) (Heteroptera: ticus and A. bouvieri as a part of IGP system provides a possible reason ) and Anisops bouvieri (Kirkaldy) (Heteroptera: of coexistence of mosquito immature along with predators in wetlands. Notonectidae) co-occur in wetlands sharing mosquito larvae as prey. As Biological regulation of mosquitoes may be affected, if appropriate pred- a consequence, an asymmetrical intraguild predation (IGP) involving D. ator numbers are not available in the habitats. rusticus as IG predator and A. bouvieri as IG prey can be possible, the outcome of which may vary with the relative density of interacting species. Based on this proposition density dependent effects on the IG prey and shared prey mortality were assessed in the laboratory using Introduction varying numbers of IG predator and shared prey (IV instar Culex quin- quefasciatus larva). In contrast to single predator system, mosquito lar- Coexistence of multiple predators of mosquitoes is observed vae were proportionately less vulnerable to predation in IGP, at low den- in mosquito larval habitats like rice fields and similar wetlands sity of shared prey. An increase in density of mosquito decreased the (Sunish & Reuben, 2002; Bambaradeniya et al., 2004; Das et al., 2006; mortality of IG prey (A. bouvieri), but the mean mortality of the IG prey Banerjee et al., 2010). In contrast to a single predator, the presence of multiple predators increases the possibility of sharing mosquito prey, thereby increasing the complexity of food web. Resource sharing by predators implies a degree of competition that may manifest as Correspondence: Goutam K. Saha, Department of Zoology, University of intraguild predation (IGP) system. In IGP, the shared prey is linked to Calcutta, 35 Ballygunge Circular Road, Kolkata 700019, India both the intraguild predator (IG predator) and the intraguild prey (IG Tel.: +91.33.2461.5445 - Fax: +91.33.2461.4849. prey). In isolation, both the IG predator and the IG prey impart a differ- E-mail: [email protected] ent level of regulation on the shared prey. Thus IGP system is a distinct phenomenon involving predators that compete with each other for Key words: Heteroptera, Diplonychus rusticus, Anisops bouvieri, intraguild shared resource. The outcome of IGP on the shared prey vary with the predation, density. identity (Polis et al., 1989; Arim & Marquet, 2004) and relative num- bers (Denno et al., 2002; Balfour et al., 2003; Borer et al., 2003; Walzer Acknowledgements: the authors acknowledge the respective Heads, et al., 2004) of interacting taxa, signifying that IGP influences stabili- Department of Zoology, University of Calcutta, Kolkata and The University of Burdwan, Burdwan, India for the facilities provided, including DST-FIST and ty and diversity of species ensembles (Walls & Williams, 2001; UGC-DRS SAP-II. Crumrine & Crowley, 2003; Rosenheim & Corbett, 2003). Considering biological control of mosquito, the influence of the top predator on the Funding: GA acknowledges the financial assitanceNon-commercial of UGC through Research IG prey and mosquito use larvae wouldonly determine the degree of regulation Award [Sanction No F.30-90(SA-II)/2009;17.09.2009] in carryng out the and efficacy