Pesticides are the main tactics for pest control because they reduce the pest population very fast and their efficiency does not depend on abiotic factors. However, the indiscriminate use of these substances can speed up the development of resistant populations and causing environmental contamination. Therefore, alternative methods of pest control are sought, such as the use of botanical compounds. Nanoencapsulation of volatile compounds has been shown to be an important tool that can be used to overcome the lack of stability of these compounds. In this work, we describe the preparation and characterization of chitosan nanoparticles functionalized with β-cyclodextrin containing carvacrol and linalool. The toxicity and biological activity were evaluated. Decreases of toxicity were observed when the compounds were nanoencapsulated. The nanoparticles presented insecticidal activity against the species Helicoverpa armigera (corn earworm) and Tetranychus urticae (spider mite). In addition, repellent activity and reduction in oviposition were observed for the mites.

Carvacrol and linalool are natural compounds extracted from plants and are known for their insecticidal and repellent activities, respectively. However, their low aqueous solubility, high photosensitivity, and high volatility restrict their application in the control of agricultural pests. The encapsulation of volatile compounds can be an effective way of overcoming such problems. Inclusion complexes between beta-cyclodextrin (β-CD) and carvacrol (CVC) or linalool (LNL) were investigated. Inclusion complexes were prepared by the kneading method. Both complexes presented 1:1 host:guest stoichiometry and the highest affinity constants were observed at 20 °C for both molecules. The nanoparticles containing carvacrol and linalool had mean diameters of 175.2 and 245.8 nm, respectively and high encapsulation efficiencies (<90%) were achieved for both compounds. Biological assays with mites (Tetranychus urticae) showed that the nanoparticles possessed repellency, acaricidal, and oviposition activities against this organism. Nanoencapsulated carvacrol and linalool were significantly more effective in terms of acaricidal and oviposition activities, while the unencapsulated compounds showed better repellency activity. The nanoformulations prepared in this study are good candidates for the sustainable and effective use of botanical compounds in agriculture, contributing to the reduction of environmental contamination, as well as promoting the effective control of pests in agriculture.

BACKGROUND: Botanical compounds from plant species are known to have pesticidal activity and have been used in integrated pest management programs. The varied spectrum of the pesticidal action of these compounds can also avoid selection of resistance in pest populations. In this study, mixtures of the botanical compounds geraniol, eugenol and cinnamaldehyde were encapsulated in zein nanoparticles to improve their stability and efficiency. Biological effects of the nano-scale formulations of the botanical compounds were evaluated against two agricultural pests: the two-spotted spider mite (Tetranychus urticae) and the soybean looper (Chrysodeixis includes).RESULTS: The formulations were stable over time (120 days) with a high encapsulation efficiency (>90%). Nanoencapsulation also provided protection against degradation of the compounds during storage and led to a decrease in toxicity to non-target organisms. The release of the compounds (especially eugenol and cinnamaldehyde) from the nanoparticles was directly influenced by temperature, and the main mechanism of release was through a diffusion-based process. Nanoencapsulated compounds also showed superior efficiency compared to the emulsified compounds in terms of repellency and insecticidal activity. CONCLUSION:The findings of this study indicate that the convergence of botanical compounds with nano-scale formulation has the potential to improve efficacy for their sustainable use in integrated pest management in agriculture.

Essential oils and their derivatives are ecofriendly biopesticides that can contribute to reducing the use of synthetic pesticides in agricultural pest control, offering advantages including less harm to humans and the environment. This work concerns hydrogel-based repellent systems containing botanical compounds that were emulsified or encapsulated in zein nanoparticles. The hydrogels were prepared according to a two-step process involving molding and cross-linking. They presented good rheological properties, even at elevated temperature (40 °C), a swelling degree of ∼30 ± 1.2%, and were able to modulate the release of active compounds. The hydrogels containing botanical compounds presented high repellency (>80%) against two important agricultural pests: whitefly (Bemisia tabaci) and two-spotted spider mite (Tetranychus urticae). These repellent systems are promising for use in sustainable agriculture, since they are based on the use of natural substances for both the matrices and the active agents. It is noteworthy that the systems can be used without direct contact with plants, which minimizes any problems related to phytotoxicity.

Nanomaterials composed of natural matrices associated with biopesticides have promising applications in sustainable agriculture. In this study, the biopesticide neem Powered by Editorial Manager® and ProduXion Manager® from Aries Systems CorporationAnswer: Thank you for your comment. We have inserted the requested information throughout the manuscript. Please verify the revised version.Reviewer: Figure 5. I do not agree with the analysis. I will suggest to apply repeated measures ANOVA or survival analysis and their curves. Answer: Thank you for your comment. We would like to explain that in Figure 5, there is no need to perform repeated measurements ANOVA because our data do not represent measurements over time of the same sample. In fact, different leaves were collected on different days after the application of the treatments to perform the test, and not a single leaf was collected and analyzed 1, 6 and 12 days latter. We have modified the figure caption for better understanding. Please verify the revised version of the manuscript.Reviewer: Line 591-801. Firstly, discussion section seems like a review of literature and many of the sentenses are awkwardly placed. I will suggest to rewrite the whole sentense. Secondly, hard to get the idea due to linguistic and syntax errors. Answer: Thank you for your comment. We have abbreviated the discussion and some cited studies were deleted. Please verify the revised version of the manuscript.Reviewer: Line 592-600. The opening paragraph of the discussion section is not appropriately written. I will suggest to rewrite this section. Answer: Thank you for your comment. We have rewritten the discussion. Please verify the revised version of the manuscript.Reviewer: Line 553-554. The sentense is awkwardly placed. Answer: Thank you for your comment. We have deleted the indicated sentence.Reviewer: Line 801. I will suggest the authors to provide a comprehensive conclusion of the study. Answer: Thank you for your comment. We have rewritten the conclusion. Please verify the revised version of the manuscript. Reviewer #2: Reviewer: I have read the manuscript entitled " Nanobiopesticide based on zein nanoparticles and neem oil: a study using target and nontarget organisms". The manuscript presents a well-written and appropriately analyzed series of experiments to determine the pesticidal and biological activity of neem oil-loaded zein nanoparticles against three pests (Acanthoscelides obtectus, Bemisia tabaci, and Tetranychus urticae), in addition to the phytotoxic effects of these nanoparticles using Phaseolus vulgaris. Overall, the manuscript is generally clear and concise report of a well-executed study. The objectives are clear; the experiments are pertinent and follow a logical reasoning; the main findings of the study are convincing and the conclusion is appropriate. The paper is clearly organized and the contribution is interesting and falls within the scope of the journal. The work is generally well written, except for certain parts of the manuscript, where a good technical ...