The role of odonate nymphs in ecofriendly control of mosquitoes and sensitivity of odonate nymphs to inorganic nutrient pollutants

Abstract

During the present research, the predatory efficiency of nymphs of six coexisting odonate species i.e., I. elegans, T. aurora, P. flavescens, L. fulva, S. decoloratum and C. servilia was studied by using the 3rd instar larvae of Cx. quinquefasciatus as prey. Among the odonate species, there was observed variation in the daily feeding rate. The highest number of mosquito larvae was ingested by the P. flavescens nymph (47.0 ± 5.1 mosquito larvae/day). The predation performance of the odonate nymph was also compared between the day and night times. The feeding rate of nymphs of most odonate species was significantly higher during the daytime as compared to night-time (P < 0.05). During the present research, feeing rates of odonate nymphs on Cx. quinquefasciatus 3rd instar larvae were also studied under varied condition of prey and predator density and water volume. Feeding rate of nymphs of each odonate species was positively correlated with increase in predator and prey density but was negatively correlated with increase in water volume. During the present research, odonate nymphs i.e., I. elegans, T. aurora and P. flavescens were exposed to various concentration of NH4+ and NO3– in the laboratory for seven days. Nymph of P. flavescens species was found least sensitive to both, NH4+ and NO3–. From the findings of the present research it was concluded that P. flavescens species is more efficient predator of Cx. quinquefasciatus 3rd instar larvae and is highly resistant to increasing water level of NH4+ and NO3.