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.

No abstract

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.

No abstract

Spodoptera frugiperda is a pest of economic importance for several crops with resistance reports to Bt crops and pesticides. Eco-friendly Bt biopesticides may be an alternative to chemical insecticides due to their selectivity and specificity. However, the efficacy of Bt biopesticides may be influenced by the association with other chemicals, such as adjuvants. This study evaluated the compatibility and toxicity of Bt biopesticides mixed with adjuvants for the control of S. frugiperda. The treatments included the association of Dipel SC and Dipel PM with adjuvants. Compatibility tests were used to evaluate the Bt mixture. Bt suspensions obtained from mixtures of Bt and adjuvants at 106 and 3 × 108 spores/mL−1 were used to evaluate S. frugiperda mortality and distilled water was used as the control. The addition of the adjuvant LI increased growth and sporulation, indicating compatibility with Bt biopesticides. The other adjuvants were toxic to reducing Bt growth and sporulation. Only the mixture of Bt with LI and Bt alone was effective to S. frugiperda. The addition of adjuvants to Bt biopesticide affect the Bt sporulation, growth and mortality.