Bioactive compound synthesis of Ag nanoparticles from leaves of Melia azedarach and its control for mosquito larvae.

Larvicidal activity of synthesized Ag nanoparticles using 2,7.bis[2-[diethylamino]-ethoxy]fluorence isolate from the Melia azedarach leaves against Aedes aegypti and Culex quinquefasciatus. Six fractions were collected and concentrated, fraction three showed a single spot on TLC which was found to be a pure compound. The structures were elucidated by analyses of UV, MS, and NMR spectral data. The maximum mortality was fluorence against A. aegypti and C. quinquefasciatus (LC50 = 7.94, LC90 = 23.82 ppm and LC50 = 13.58 and LC90 = 40.03 ppm). The synthesized nanoparticles were characterized and confirmed as Ag nanoparticles by using UV-visible spectroscopy, XRD and HRTEM analysis. The maximum activity was observed in synthesized AgNPs against A. aegypti and C. quinquefasciatus (LC50 = 4.27 and 3.43 µg/mL; LC90 = 12.61 and 10.29 µg/mL). Rephrase test was studied to analyze the toxicological effects of Mesocyclops pehpeiensis for 24 h at synthesized AgNPs. This method is considered as an innovative alternative approach that can be used to control mosquitoes.

Fluorescence quenching and photocatalytic degradation of textile dyeing waste water by silver nanoparticles.

Silver nanoparticles (Ag NPs) of different sizes have been prepared by chemical reduction method and characterized using UV-vis spectroscopy and transmission electron microscopy (HRTEM). Fluorescence spectral analysis showed that the quenching of fluorescence of textile dyeing waste water (TDW) has been found to decrease with decrease in the size of the Ag NPs. Experimental results show that the silver nanoparticles can quench the fluorescence emission of adsorbed TDW effectively. The fluorescence interaction between Ag NPs (acceptor) and TDW (donor) confirms the Förster Resonance Energy Transfer (FRET) mechanism. Long range dipole-dipole interaction between the excited donor and ground state acceptor molecules is the dominant mechanism responsible for the energy transfer. Furthermore, photocatalytic degradation of TDW was measured spectrophotometrically by using silver as nanocatalyst under UV light illumination. The kinetic study revealed that synthesized Ag NPs was found to be effective in degrading TDW.

Laboratory evaluation of Mesocyclops aspericornis as a biocontrol agent of Aedes aegypti.

Mesocyclops aspericornis abounds in village ponds. Hence, the predatory capacity of M. aspericorniswas considered for use as a biological control agent for Aedes aegypti mosquitoes. In laboratoryexperiments, M. aspericornis consumed 33–50 mosquitoe larvae within 24-hours time period. M.aspericornis preyed upon only the first instar larvae of Ae. aegypti within a few seconds after theirintroduction. It started feeding on the tail portion first and ended with the head capsule. The meanvalue (triplicate) showed that the predatory capacity was 45.76 against the control 1.2. M. aspericornisprefers only the first instar mosquitoe larvae and feeds on them voraciously. When the Aedes larvaeattained the second instar stage, M. aspericornis attacked and killed them.