Produtos naturais em estratégias de controle de pragas: feromônios e produtos vegetais

Abstract

The use of pheromones and plant volatiles as alternative methods to the indiscriminate use of synthetic pesticides in pest control has been widely studied. Sustainable and effective tactics, such as integrated pest control and/or management, become a viable option for replacement and/or reduction of chemical usage, in addition to minimizing economic losses. The Erinnyis ello (Linnaeus, 1758) (Lepidóptera: Sphingidae) is considered one of the main pests of cassava (Manihot esculenta Crantz), due to the high capacity of leaf consumption of caterpillars, across large areas of plantations. The use of semiochemicals in this culture presents itself as a promising strategy. For this purpose, substances emitted by this pest have been identified, which can be used in attractive baits. Collection of eggs, caterpillars and pupae were carried out in municipalities in the State of Alagoas. Insect breeding and reproduction was established until adulthood. Aeration and solvent extraction techniques from insect body parts allowed for volatile compounds to be obtained. Analysis of Gas Chromatography (GC) coupled with Mass Spectrometry (MS) revealed the presence of sex specific compounds, whose specific action was supported by Electroanthenography (GC-EAG) analyzes of extracts of both sexes. A Scanning Electron Microscopy (SEM) analysis of antennas indicated a differentiation between the sexes, with the presence of six and seven types of sensilla in the male and female antennas, respectively. Insects detect volatile molecules in the air through the olfactory sensilla. Therefore, the knowledge of the molecular mechanisms of this system can promote the development of new effective methods in pest control. The Helicoverpa armigera (Hübner, 1805) (Lepidoptera: Noctuidae) is considered the most important pest in worldwide agriculture and is resistant to chemicals and formulations of its sexual pheromone. As a result, the structure and function of H. Armigera’s Odor Binding Proteins (OBPs) have been evaluated. A cDNA library was built from the RNA of the insect’s antennae and used in the clonning of the OBPs’ genes (HarmPBP1 and HarmGOBP1) for expression in Escherichia coli. The purified proteins were analyzed by Gel Electrophoresis and MS with electrospray ionization (ESI). The study of the affinity of the HarmPBP1 compound with the main component of H. Armigera’s pheromone was carried out by Deuterium Hydrogen Exchange (MS-HDX). It indicated the protein's affinity for the ligand, which was supported by a Fluorescence Spectroscopy analysis also applied to HarmPBP1. The latter was conducted with with seven selected compounds, four of which showed a displacement of the fluorescent probe bounded to the protein. Alternatives aimed at pest control and monitoring also encompass the diversity of active compounds in plant-based products. Anogenaceous acetogenins are a series of natural products that can be isolated from different parts of Annonaceae species and present a striking biological activity as a larvicide. Experiments have benn carried out aiming at the structural elucidation of the active isolated ingredient of the soluble fraction in chloroform (ACCR-2) from the ethanolic extract of the root bark of Annona crassiflora Mart. (Annonaceae), in a phytochemical study guided by the activity of Aedes aegypti (Linnaeus, 1762) (Diptera: Culicidae).