Abstract
Mosquitoes represent an important threat for lives of millions of people worldwide, acting as vectors for devastating pathogens, such as malaria, yellow fever, dengue, and West Nile. In addition, pathogens and parasites polluting water also constitute a severe plague for populations of developing countries. Here, we investigated the mosquitocidal and antibacterial properties of
Aloe vera
leaf extract and silver nanoparticles synthesized using
A. vera
extract
.
Mosquitocidal properties were assessed in laboratory against larvae (I-IV instar) and pupae of the malaria vector
Anopheles stephensi
. Green-synthesized silver nanoparticles were tested against
An. stephensi
also in field conditions. Antibacterial properties of nanoparticles were evaluated against
Bacillus subtilis
,
Klebsiella pneumoniae
, and
Salmonella typhi
using the agar disk diffusion and minimum inhibitory concentration protocol. The synthesized silver nanoparticles were characterized by UV–vis spectrum, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). In laboratory conditions, the
A. vera
extract was toxic against
An. stephensi
larvae and pupae, even at low dosages. LC
50
were 48.79 ppm (I instar), 59.09 ppm (II instar), 70.88 ppm (III instar), 83.58 ppm (IV instar), and 152.55 ppm (pupae). Green-synthesized silver nanoparticles were highly toxic against
An. stephensi
. LC
50
were 3.825 ppm (I instar), 4.119 ppm (II instar), 4.982 ppm (III instar), 5.711 ppm (IV instar), and 6.113 ppm (pupae). In field conditions, the application of
A. vera
-synthesized silver nanoparticles (10 × LC
50
) leads to
An. stephensi
larval reduction of 74.5, 86.6, and 97.7 %, after 24, 48, and 72 h, respectively. Nanoparticles also showed antibacterial properties, and the maximum concentration tested (150 mg/L) evoked an inhibition zone wider than 80 mm in all tested bacterium species. This study adds knowledge about the use of green synthesis of nanoparticles in medical entomology and parasitology, allowing us to propose
A. vera
-synthesized silver nanoparticles as effective candidates to develop newer and safer mosquitocidal control tools.