Efficacy of porous silica nanostructure as an insecticide against filarial vector Culex pipiens (Diptera: Culicidae)
2022
Baz, Mohamed M. | El-Barkey, Nehad M. | Kamel, Aida S. | El-Khawaga, Aya H. | Nassar, Mostafa Y.
There is a need to formulate new insecticides against insect-borne diseases. Silica nanoparticles (SNPs) prepared by sol–gel (A₈₀₀) and sol–gel/combustion (B₈₀₀) methods were tested at different concentrations of 5, 25, 50, 100, and 200 ppm after 24 and 48 h on Culex pipiens larvae. The synthesized SiO₂ was characterized by using different spectroscopic techniques. Our data revealed that silica nanoparticles (B₈₀₀) showed high larvicidal activity as the LC₅₀ values were 19.7, 37.4, 61.1, and 85.2 for the 1ˢᵗ, 2ⁿᵈ, 3ʳᵈ, and 4ᵗʰ larval instar and 234.8 ppm for the pupal stage at 24 h, respectively. A higher mortality percentage was observed in the 1ˢᵗ larval instar than in all the other immature life stages treated with silica nanoparticles. At 200 ppm, the mortality reached 100% and 90% on treating mosquitoes with B₈₀₀ and A₈₀₀ silica nanoparticles, respectively for the1ˢᵗ larval instar compared to 81.7% and 63.3% for the 4ᵗʰ larval instar at 24 h. On treatment with an LC₅₀ concentration of the B₈₀₀ and A₈₀₀ silica nanoparticles, the larvae took 22.7 and 18.4 days respectively, compared to 13.3 days for the control, to reach the pupal stage. Glutathione-S-transferase and α-esterase activities increased significantly after treatment with the LC₅₀ concentration of SNPs (A₈₀₀ &B₈₀₀). Conversely, alkaline/acid phosphatase enzyme activity and total protein were reduced. We suggest the use of silica nanoparticles in mosquito control as an eco-friendly approach.
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