Formulation of abamectin and plant oil-based nanoemulsions with efficacy against the two-spotted spider mite Tetranychus urticae (Acari: Tetranychidae) under laboratory and field conditions

Abstract

Due to the harmful effects of synthetic chemical acaricides on ecosystems and human health, there is increasing interest in the use of nanotechnology to fabricate eco-friendly nanoemulsions based on plant oils in the field of spider mite control. In this study, nanoemulsions of abamectin, garlic, and neem oils were prepared by a high-energy approach and characterized by transmission electron microscopy. The droplet sizes of all tested nanoemulsions were less than 100 nm. The acaricidal activities of the prepared nanoemulsions compared to abamectin were evaluated against a susceptible laboratory strain of Tetranychus urticae Koch (Acari: Tetranychidae) under laboratory and field conditions. The results showed that abamectin nanoemulsion was the most toxic compound against adult females of T. urticae followed by abamectin emulsion. Neem nanoemulsion had moderate toxicity and garlic nanoemulsion had the lowest toxicity. The effects of tested compound residues on egg deposition and egg hatching in descending order were as follows: abamectin nanoemulsion > abamectin emulsion > neem oil nanoemulsion < garlic oil nanoemulsion. In the field experiment, all tested compounds were effective in reducing the population density of T. urticae in the motile stage, with mean reductions ranging between 66.08% and 95.24% for all compounds. The most effective compound was abamectin nanoemulsion. The results of the present study demonstrate that nanoemulsion enhanced the biological activity of abamectin. Further, neem and garlic oil nanoemulsions have potential utility as environmentally friendly acaricides in integrated pest management programs.