Toxicidade de óleos essenciais de lamiáceas e da nanoemulsão de Pogostemon cablin (Blanco) Benth (Lamiaceae) para Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae)

Abstract

The fall armyworm Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) is a pest that feeds on more than 350 species of plants and causes damage to several agricultural crops, mainly corn. The most used forms of control are the use of genetically modified plants and synthetic insecticides, which can cause the selection of resistant populations and environmental contamination. In this sense, essential oils (EOs) present themselves as a promising alternative for the control of insect pests. Thus, this study aimed to evaluate the toxicity of EOs from plants of the Lamiaceae family against S. frugiperda. The most bioactive EO was nanoemulsified and subjected to further tests with this insect. Initially, the bioactivity of EOs from Lamiaceae Lavandula angustifolia Mill, Thymus vulgaris L., Pogostemon cablin (Blanco) Benth and Salvia sclarea L. para S. frugiperda was evaluated, in topical and ingestion tests. The median lethal dose (LD50) was determined for all EOs tested topically. The median lethal concentration (LC50) was determined only for the EO of P. cablin because it showed better bioactivity. The EOs were chemically characterized and the major compound of P. cablin, patchoulol, it was subjected S. frugiperda. Finally, the EO of P. cablin was nanoemulsified, characterized and used in tests with S. frugiperda. All EOs evaluated in this work were toxic to S. frugiperda in a topical application test. However, in an ingestion test, only the EO of P.cablin was bioactive. The majority compound of the OE of P. cablin, the patchoulol, was toxic against S. frugiperda in an ingestion trial, however, the bioactivity was not as pronounced in a topical application test. It was found that the nanoemulsion of EO of P. cablin was more toxic against S. frugiperda than the EO in its conventional form. Thus, in the present work, the toxicity of EOs against S. frugiperda was observed, and therefore have potential for the development of further research and studies. It is also concluded that the EO of P. cablin, in its nanoemulsified form, showed greater toxicity to the pest and a reduction in the amount of EO used, compared to the conventional one, standing out as a promising agent for the development of formulations aimed at the ntegrated pest control and management.