Description
Introduction-Objectives :
Malaria is one of the most common diseases that affect pregnant women in Sub Saharan Africa. This disease is a parasitic infection caused by the transmission of Plasmodium falciparum during the blood feed of female Anophele. Mosquitos are considered as potential reservoirs of parasites, that is why due to their rapid development, the control vector is a key factor in the fight against malaria because it regulates the transmission of this disease. The use of chemical insecticides is harmful for human and their environment, particularly for the pregnant women. It became urgent to develop the new approaches which could be safe, ecofriendly and, low cost. In this study, we proposed the use of silver nanoparticles as a bioinsecticide in vector control against malaria.
Méthodology :
Silver nanoparticles were synthesized from the aqueous extracts of fresh leaves of Psidium guajava (P. guajava) and Ocimum basilicum (O.basilicum). Their biophysical characteristics were obtained by Ultraviolet-visible spectrometry, Fourier transform Infrared spectroscopies and X-ray powder diffraction. A concentration variation between 0.5 and 90.6 ppm of the obtained nanoparticles was tested on Anopheles gambiae stage 4 larvae to evaluate their biological activity.
Results and discussion:
This study reports the larvicidal activity of silver nanoparticles generated from aqueous plant extracts on Anopheles gambiae. It has been found that, plant extracts have appropriate reducing and stabilizing characteristic during the preparation of AgNPs. The leaves fresh aqueous extract is characterized by its yellow color. However, after synthesis has turned to brown color indicating the nanoparticles formation.The wavelengths between 400-600nm confirmed experimentally the formation of silver nanoparticles. They were crystalline in nature and constituted by the following chemical groups : Alcohols, amines, alkyls, aldehydes and ketones. The larvicidal effect against Culex pipiens has been tested. The LC50 determinated after 24 h and 48 h. The results showed an increase in potency with time. The mortality of AgNPs Psidium guajava and Ocimum basilicum having concentration of 1ppm to 30.2 and 2.0 to 2.5 ppm after 24 h respectively. The The LC50 for AgNPs@Psidium guajava and Ocimum basilicum were 19.55 ppm and 1.54 ppm after 24 h, respectively, while after 48 h the LC50 reached 8.73ppm and 0.95ppm respectively
Conclusion :
The green synthesis of silver nanoparticles using Psidium guajava and Ocimum basilicum water extract were effective against Anopheles gambiae larvae. Their insecticide properties that do not require the presence of any harmful material. This method is eco-friendly, low-cost, and safe for human health and his environment
Biocontrol agents derived from this methodology could be considered as a suitable alternative to control vector-borne diseases in developing countries.
Keywords: Vector control, Anopheles gambiae, silver nanoparticles, Psidium guajava, Ocimum basilicum.
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