Effect of Habitat Modifications on Predation Potential of <i>Anisops sardea</i> (Hemiptera: Notonectidae) against Larvae of Culex vishnui, Vector of Japanease Encephalitis

Abstract

To prevent emergence of insecticide resistance in vector population & biological magnification of toxic insecticides through food chain, more attention is now put on application of biological control system to reduce the population of vectors. Present study was carried out to assess the effect of habitat modifications on the predatory ability of Anisops sardea (Hemiptera: Notonectidae) against immature of Culex Vishnui (Diptera: Culicidae) group of mosquitoes in laboratory and semi-field bioassay.To study the effect of habitat modifications, laboratory based predatory experiments were carried with A. sardea as predator and Cx.vishnui group of mosquitoes as prey species. To determine prey preference of predator species, predatory experiment was done in presence of mosquitoes belongs to different genera. For a long-term study on predation rate, for 15 consecutive days, 10 adult individuals of A. sardea were kept in a plastic bucket of 20 L capacity in open natural condition and number of mosquito larvae consumed/per day was calculated.Result of single factor ANOVA analysis revealed that habitat modifications have significant effect on the predatory rate of A sardea as calculated F value (34.10) is significantly higher than table value (F crit =2.156). Pair wise ‘t test’ revealed significant variations in the predation rate when different habitat combinations were analyzed. Results of selectivity index, niche breadth and food breadth were also evaluated. Long term bioassay in semi-field condition revealed that predatory rates were almost similar throughout the study period.Considering the habitat specificity, prey preference and the rate of predation in semi field condition, it can be concluded that A. sardea can be used as potential biological control agent against Culex Vishnui group of mosquitoes.