Nanoencapsulamento DO ÓLEO ESSENCIAL DAS FOLHAS E FRUTOS DE Xylopia aromatica Lamm. E SUA ATIVIDADE FRENTE A OVIPOSIÇÃO DE Bemisia tabaci (Genn.) (Hemiptera: Aleroydidae) BIÓTIPO B

Abstract

Bemisia tabaci, popularly known as whitefly, is one of the most important agricultural pests worldwide due to its wide geographic distribution and the numerous problems it causes in crops. The whitefly is responsible for the transmission of several viruses, such as the bean golden mosaic virus, and can cause damage of up to 100% of the crop in agricultural production. Moreover, B. tabaci has a short life cycle, which allows it to have great adaptability to insecticide active ingredients and to develop resistance; thus, a high amount of insecticide is used to control this pest. To reduce the harmful effects of pesticides, there is increasing interest in natural products with insecticidal properties. Natural products that are nanoencapsulated protect the active ingredient against environmental degradation in addition to reducing the doses used. In this context, the current study aimed to evaluate the insecticidal activity of natural and nanoencapsulated essential oils extracted from leaves and fruits of Xylopia aromatica against whitefly in bean plants. The essential oils were extracted by hydrodistillation in a Clevenger apparatus, with average yields of 0.05% and 0.8% for leaves and fruits, respectively. According to the chemical analysis, the major compounds of the leaf essentials oils were -elemene (38.7%), sabinene (21.46%), α-pinene (7.12%), β-pinene (6.70%) and limonene (2.88%), whereas the major compound of the fruit essential oils was sabinene (69.7%). The nanoprecipitation of a preformed polymer to obtain PCL nanoparticles containing essential oils proved to be effective, with a mean encapsulation efficiency of 95%. The factorial planning analysis indicated the nanospheres as the best option because they were more economically and environmentally viable. The in vitro release tests showed that after 72 h, 75% and 81% of the essential oils of X. aromatica leaves and fruits, respectively, diffused. In studies of accelerated degradation caused by UV light, it was observed that the nanospheres substantially protected the essential oil from degradation. The bioassays showed that natural and nanoencapsulated essential oils reduced B. tabaci oviposition in bean plants both in the free-choice and the no-choice tests as the concentrations increased. The higher concentrations had up to 98% efficacy. Thus, the results suggest that both natural and nanoencapsulated essential oils from X. aromatica leaves and fruits can be used as an alternative for B. tabaci control. Additionally, nanotechnology ensures dispersion in an aqueous medium, protects against environmental degradation, prolongs the insecticidal effect through gradual release and may guarantee insecticide activity at a specific active site, thus reducing the development of resistance.