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Kalimuthu Kovendan,Balamurugan Chandramohan,Devakumar Dinesh,Dhandapani Abirami,Periasamy Vijayan,Marimuthu Govindarajan,Savariar Vincent,Giovanni Benelli 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.4
Mosquitoes transmit serious diseases to humans and animals, causingmillions of deaths every year. Effective insecticides of natural origin for eco-friendly vector control are a priority. In this study, silver nanoparticles (AgNPs) biosynthesized using as cheap Psychotria nilgiriensis leaf extractwere tested on larvae and pupae of Aedes aegypti (Diptera: Culicidae). Biophysical characterizationwas carried outwith UV–vis spectrophotometry, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Larvae were exposed to varying concentrations of aqueous extract of synthesized AgNPs for 24 h. The maximum mortality was observed for green-synthesized AgNPs. Moreover, the combined treatment of leaf extract of P. nilgiriensis and AgNPs lowered the plant extract LC50 to 92.87, 115.27, 140.37, 169.30 and 212.55 μg/ml. The effectiveness of green synthesized AgNPs was confirmed against eggs and adults of A. aegypti. Furthermore, we showed that the predatory efficiency of Poecilia sphenops on A. aegypti was not reduced after the exposure at sublethal doses of AgNPs. Predation in the control was 65% (larva I) and 49.62% (larva II). Predation against late-instar larvae was minimal. In AgNPs-treated environment (3 ppm), predation was boosted to 90.25% (larva I) and 76.50% (larva II), respectively. Overall, P. nilgiriensis-synthesized AgNPs could be proposed at ultra-low doses to reduce larval population of dengue vectors enhancing predation rates of P. sphenops.
Marimuthu Govindarajan,Mohan Rajeswary,S.L. Hoti,Kadarkarai MURUGAN,Kalimuthu Kovendan,Subramanian Arivoli,Giovanni Benelli 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.1
Mosquito-borne diseases represent a deadly threat for millions of people worldwide. However, the use of synthetic insecticides to control Culicidae may lead to high operational costs and adverse non-target effects. Plantborne compounds have been proposed for rapid extracellular synthesis ofmosquitocidal nanoparticles. Their impact against biological control agents of mosquito larval populations has been poorly studied. In this study, we synthesized silver nanoparticles (Ag NPs) using the Clerodendrumchinense leaf extract as reducing and stabilizing agent. The biosynthesis of AgNP was confirmed analyzing the excitation of surface Plasmon resonance using ultraviolet–visible (UV–vis) spectrophotometry. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed the clustered and irregular shapes of Ag NP. The presence of silver was determined by energy dispersive X-ray (EDX) spectroscopy. Fourier transform infrared (FTIR) spectroscopy analysis investigated the identity of secondary metabolites,which may act as Ag NP capping agents. The acute toxicity of C. chinense leaf extract and biosynthesized Ag NP was evaluated against larvae of Anopheles subpictus, Aedes albopictus and Culex tritaeniorhynchus. Compared to the leaf aqueous extract, biosynthesized Ag NP showed higher toxicity against A. subpictus, A. albopictus, and C. tritaeniorhynchus with LC50 values of 10.23, 11.10 and 12.38 μg/mL, respectively. Biosynthesized Ag NPswere found safer to non-target organisms Diplonychus indicus, Anisops bouvieri and Gambusia affinis, with respective LC50 values ranging from647.05 to 6877.28 μg/ml. Overall, our results highlight that C. chinense-fabricated Ag NP are a promising and eco-friendly tool against larval populations ofmosquito vectors of medical and veterinary importance, with negligible toxicity against non-target aquatic organisms. © 2015 Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection