Preparation and Characterization of Efficient and Safe Rotenone Solid Nanodispersion by Self-Emulsifying Technique

Area of Science:

• Agricultural Science
• Materials Science
• Nanotechnology

Background:

• Botanical insecticides like rotenone (Rot) face challenges including poor water solubility, rapid photodegradation, and limited targeting efficiency.
• Self-emulsifying solid nanodispersion (SND) technology offers a promising approach for creating eco-friendly nano-formulations due to its simple, energy-efficient, and scalable process.

Purpose of the Study:

• To investigate the efficacy of self-emulsifying solid nanodispersion technology in overcoming the limitations of botanical insecticides, using rotenone as a model compound.
• To prepare and characterize a rotenone-based solid nanodispersion (Rot-SND) and evaluate its performance compared to commercial formulations.

Main Methods:

• Rotenone (Rot) was formulated into a solid nanodispersion (Rot-SND) using a self-emulsifying method with optimized parameters, including specific concentrations of Rot, surfactant complexes (Ethylan 992 and EL-80), and lactose.
• Characterization of Rot-SND included particle size, polydispersity index (PDI), contact angle measurements, foliar retention studies, photodegradation assays, and toxicity assessments against target pests (Aphis gossypii) and non-target organisms (mosquito larvae).
• Field trials were conducted to evaluate the long-term efficacy of Rot-SND in controlling A. gossypii compared to commercial emulsifiable concentrates (ECs).

Main Results:

• The optimized Rot-SND formulation exhibited excellent storage stability and increased Rot pseudo-solubility by over 250 times, with an average particle size of 101.19 nm and a PDI of 0.21.
• Rot-SND demonstrated superior foliar retention and reduced contact angles on plant leaves compared to ECs. It also showed enhanced photostability, with a 27.01% reduction in degradation rate.
• The toxicity of Rot-SND against A. gossypii was 3.01 times higher than ECs (LC50 = 1.45 µg a.i./mL). Field studies showed significantly higher control efficacy (88.10% vs. 77.02% on day 10), and a 2.34-fold decrease in toxicity towards non-target mosquito larvae.

Conclusions:

• Self-emulsifying solid nanodispersion technology effectively addresses the limitations of rotenone, improving its solubility, foliar affinity, photostability, bioactivity, and eco-safety.
• Rot-SND represents a novel, eco-friendly, and highly efficient formulation strategy for botanical pesticides, offering a viable alternative to conventional formulations.