Aristolochia indica green-synthesized silver nanoparticles: A sustainable control tool against the malaria vector Anopheles stephensi?

Malaria is a life-threatening disease caused by parasites transmitted to people and animals through the bites of infected mosquitoes. We biosynthesized silver nanoparticles (AgNP) using Aristolochia indica extract as reducing and stabilizing agent. AgNP were characterized by UV-vis spectroscopy, FTIR, SEM, EDX and XRD. In laboratory, LC50 of A. indica extract against Anopheles stephensi ranged from 262.66 (larvae I) to 565.02 ppm (pupae). LC50 of AgNP against A. stephensi ranged from 3.94 (larvae I) to 15.65 ppm (pupae). In the field, the application of A. indica extract and AgNP (10 × LC50) leads to 100% larval reduction after 72 h. In laboratory, 24-h predation efficiency of Diplonychus indicus against A. stephensi larvae was 33% (larvae II) and 57% (larvae III). In AgNP-contaminated environment (1 ppm), it was 45.5% (larvae II) and 71.75% (larvae III). Overall, A. indica-synthesized AgNP may be considered as newer and safer control tools against Anopheles vectors.

A novel method of controlling a dengue mosquito vector, Aedes aegypti (Diptera: Culicidae) using an aquatic mosquito predator, Diplonychus indicus (Hemiptera: Belostomatidae) in tyres

An investigation was undertaken to evaluate the biocontrol potential of a mosquito predator, Diplonychus indicus, against the immatures of dengue vectors breeding in used tyres. Two gardens were selected and ten tyres each filled with water were kept in different sites of both gardens. One was considered as “control” where no predator was used, whereas in the tyres kept in the “experimental” garden, two second instars of D. indicus were released into each tyre. The absolute density of larvae, pupae and man-landing rate of dengue vector were monitored at weekly intervals. After one year, the predators released in the tyres in the experimental garden were removed and it became the control garden whereas two second instars predators were released into the tyres kept in the control garden which then became the experimental garden. When D. indicus was introduced into the tyres kept in the experimental garden, a drastic reduction of 95% and 98% respectively of late instars and pupae of Ae. aegypti was observed. But there was no reduction in the tyres kept in the control garden. The density of early instars of Ae. aegypti fluctuated in the tyres kept in both the gardens during different months of the year. There were significant differences between the densities of early, late instars and pupae of Ae. aegypti in experimental and control gardens (early: p