Toxicity and Growth-Disruptive Effects of Silica, Zinc and Aluminum Oxide Nanoparticles on Spiny Bollworm, Earias insulana

Enas E. Nasr and Shady Selim

Background and Objective: Nanoparticles (NPs) are the most efficient technique of pest control without disturbing the potential environmental balance. This study was carried out to compare the toxicity effects of Silica, Zinc and Aluminum oxide NPs on growth, development, malformation and chitin formation parameters of Earias insulana. Materials and Methods: Newly hatched larvae fed on the treated diet for 48 hrs following by the untreated one until pupation. The toxicity impacts of LC₅₀values for each tested NPs were calculated. The fourth instar larvae prepared for scanning electron microscopy and also for defining the chitin formation. Results: The ZnONPs was the highest toxicity, followed by SiO₂ and Al₂O₃ NPs. The treatment with ZnONPs has scored an extreme reduction in the weight compared to other tested NPs. The growth rate inhibition decreased gradually until the fourth instars and then increased slightly in the prepupae and pupae in favor of ZnONPs, while Al₂O₃ NPs was the least effective one. Under-tested NPs, the increase in the larval and pupal periods led to a sharp reduction in the developmental rate and a significant increase in larval deformations. Besides, the least chitin formation ratio was registered in response to ZnONPs. By using electron microscopy, distinct differences were observed in the distribution of NPs on the cuticle surface of the fourth-instars body parts. Conclusion: This study recommends the practical use of ZnO, SiO₂ and Al₂O₃ NPs, respectively, in pest control programs of E. insulana as safe alternative materials.

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