Essential oils (EOs) are promising active ingredients for biopesticides, although their use under field conditions is limited by several criticisms concerning their high volatility and degradability. To overcome these negative qualities, EOs can be encapsulated inside nanostructures (i.e. nanoparticles and nano-emulsions), which can guarantee the preservation of the insecticidal properties. In the current study, oil in water (O/W) nano-emulsions of seven commercial EOs (15 % w/w of anise, artemisia, fennel, lavender, peppermint, rosemary, sage) were developed using different non-ionic surfactants and formulation processes, to identify the best possible surfactant/process to produce stable nano-formulations. The EOs were firstly examined by gas-chromatography analyses to identify their chemical constituents. Sage, rosemary, peppermint, lavender and artemisia EOs were characterized by high percentage (up to 50 % of the detected compounds) of oxygenated monoterpenes, while fennel and anise EOs were mainly constituted by phenylpropenes (e.g. anethol). Then, nano-emulsions were developed via the self-emulsifying process alone or in combination with sonication, using four surfactants with different Hydrophilic Lipophilic Balance (HLB) index (5 % w/w of Tween 20, Tween 80, Span 20 or Span 80). The physical characteristics (droplet size and surface charge) of nano-emulsions were analyzed using the dynamic light-scattering technique. Sonicated nano-formulations presented smaller and more homogeneous size of the micelles than the non-sonicated ones, resulting in more stable nano-emulsions. Furthermore, usually emulsions produced using Tween 80 as surfactant gave the best results in terms of droplet size and polydispersity index (PDI) values. Therefore, Tween 80 sonicated nano-emulsions were examined during a storage period of 28 weeks to determine their stability over time and possible alteration of their physical characteristics. Results suggest that these nano-formulations had a good stability over time, since relatively small increases in PDI and size values were recorded. Formulation stability is a key issue to consider when proposing botanical biopesticides for agricultural applications. Our study reports the first step in the introduction of EO-based nano-emulsions into practical application.

精油（EOs）是生物农药的有希望的活性成分，尽管在田间条件下使用精油受到其高挥发性和可降解性的若干批评的限制。为了克服这些负面特性，可以将EOs封装在纳米结构（即纳米颗粒和纳米乳剂）内部，这可以保证保留杀虫特性。在当前的研究中，使用不同的非离子表面活性剂开发了7种市售EO（水，茴香，蒿，茴香，熏衣草，薄荷，迷迭香，鼠尾草的15％w / w）的水包油（O / W）纳米乳液。配方过程，以确定可能的最佳表面活性剂/工艺，以产生稳定的纳米配方。首先通过气相色谱分析检查EO，以鉴定其化学成分。鼠尾草，迷迭香，薄荷，薰衣草和蒿的EOs的特征是含氧的单萜的含量高（最多占检测到的化合物的50％），而茴香和茴香的EOs主要由苯丙烯（如茴香脑）组成。然后，使用四种具有不同亲水亲油平衡（HLB）指数（吐温20，吐温80，Span 20或Span 80的5％w / w）的表面活性剂，通过单独或结合超声处理的自乳化工艺开发出纳米乳液。 ）。使用动态光散射技术分析了纳米乳液的物理特性（液滴大小和表面电荷）。超声处理的纳米制剂的胶束尺寸比非超声处理的更小，更均匀，从而产生更稳定的纳米乳液。此外，通常，就液滴大小和多分散指数（PDI）值而言，使用Tween 80作为表面活性剂生产的乳液效果最佳。因此，在储存28周的过程中检查了Tween 80超声处理的纳米乳液，以确定其随时间变化的稳定性以及其物理特性可能发生的变化。结果表明，这些纳米制剂随时间推移具有良好的稳定性，因为记录了PDI和尺寸值的相对较小的增长。在为农业应用推荐植物性生物农药时，配方稳定性是要考虑的关键问题。我们的研究报告了将EO基纳米乳液引入实际应用的第一步。在28周的存储期内检查了Tween 80超声处理的纳米乳液，以确定其随时间变化的稳定性以及其物理特性可能发生的变化。结果表明，这些纳米制剂随时间推移具有良好的稳定性，因为记录了PDI和尺寸值的相对较小的增长。在为农业应用推荐植物性生物农药时，配方稳定性是要考虑的关键问题。我们的研究报告了将EO基纳米乳液引入实际应用的第一步。在28周的存储期内检查了Tween 80超声处理的纳米乳液，以确定其随时间的稳定性以及其物理特性可能发生的变化。结果表明，这些纳米配方随时间推移具有良好的稳定性，因为记录到的PDI和尺寸值相对较小。在为农业应用推荐植物性生物农药时，配方稳定性是要考虑的关键问题。我们的研究报告了将EO基纳米乳液引入实际应用的第一步。在为农业应用推荐植物性生物农药时，配方稳定性是要考虑的关键问题。我们的研究报告了将EO基纳米乳液引入实际应用的第一步。在为农业应用推荐植物性生物农药时，配方稳定性是要考虑的关键问题。我们的研究报告了将EO基纳米乳液引入实际应用的第一步。