Toxicity of Neem Oil nano-emulsion formulations against adults of Sitophilus Oryzae (L.) and Tribolium Castaneum (Herbst)

Abstract

The study was conducted to evaluate the toxicity of Azadirachtin formulated as nano-emulsion against two serious pest species of stored products, Sitophilus Oryzae and Tribolium Castaneum. Pseudoternary phase diagrams were constructed consisting emulsion system of neem oil, surfactant and water. Two formulations coded as Neem-Polysorbate and Neem-APG were selected from the isotropic regions and characterized for particle size, zeta potential and "thermostability. The particle size of Neem-Polysorbate and Neem-APG were 253 and 328 nm while the zeta potentials were 37.4 and 31.9 mV, respectively. Both formulations were stable. The nano-emulsion formulations of Azadirachtin were then tested against adults S. Oryzae and T. Castaneum at 0.5, 0.75 and 1% Azadirachtin concentration using food impregnation method. Both formulations gave significantly higher mortality after 24 and 48 h against S. Oryzae and T. Castaneum compared to non-formulated neem oil at all concentrations tested.