MgO/Y2O3 doped Eucalyptus globulus essential oil nanoemulsion hybrid for enhanced larvicidal activity against mosquitoes and eco-safety assessment.

Mosquito-transmitted affliction represents a global health threat. Eco-friendly, biodegradable, and target-specific phytochemical larvicides are much needed. Therefore, the study aims to develop a metal-organic framework for next-generation nano-larvicides using plant extract essential oils. Essential oils of Catharanthus roseus, Coriandrum sativum, Dodonaea viscosa, Eucalyptus globulus, Lantana camara, Leucas aspera, Parthenium hysterophorus, and Vitex negundo were extracted, and assessed for their larvicidal potential against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. Among them, E. globulus derived EO (EG-EO) showed good efficacy and further to enhance its bioavailability, stability, and to improve the larvicidal activity, a nanoformulation hybrid system of Magnesium oxide and Yttrium oxide (MgO-Y₂O₃) nanoparticles (EG-HY) was formulated and studied against 3rd and 4thinstar larvae of the dengue, filariasis, and malaria vectors larvae at different concentrations (12.5 to 100 ppm). Interestingly, hybrid nanoemulsion showed 100% mortality with LC50 values of 14.37 ppm (Ae. aegypti), 21.90 ppm (An. stephensi), and 19.47 ppm (Cx. quinquefasciatus), respectively. GC--MS revealed bioactive compounds like dihydrocarveol (4.27%), and isopulegol (3.23%); indicating the presence of terpenoids, responsible for larvicidal activity. FTIR, and UV-Vis confirmed the functional moiety, and successful formulation of EG-HY, respectively. HRSEM, and TEM image showed uniform dispersion of nano-emulsion. The mean droplet size of the prepared EG-HY was 91.84 nm, with a PDI of 1.00. Toxicity assessment using zebrafish model revealed good tolerance at lower concentrations, while higher concentrations affected hatching and development. Overall, these findings concluded that EG-HY act as promising and effective natural larvicides with concentration-dependent toxicity towards non-target organisms.