Identificação, avaliação da atividade e síntese de semioquímicos para o controle de pragas agrícolas

Abstract

Brazilian agricultural production is constantly growing. Development of new technologies is necessary to ensure a more sustainable development, in addition to being a way to benefit this sector to keep the country among the largest producers and exporters in the world. The occurrence of pests in economically important crops is gaining more importance due to the way of planting and the rise in the average annual temperature. This has caused considerable losses, in addition to raising production costs, since agrochemicals are still the most used to control these insects. Behavioral control, based on the use of semiochemicals, is an important component in Integrated Pest Management (IPM), as they are safe and environmentally friendly products. The present work aimed to identify volatile compounds in Ascia monuste orseis, a Brassicaceae pest, in addition to preparing, individually, pheromonal components of three other pests: (Z,E)-7,11-hexadecadienyl acetate, the main component of the pheromone sex of Pectinophora gossypiella and Sitotroga cerealella, cotton pests and stored grains, respectively; (Z,Z)-7,11-hexadecadienyl acetate, also the main component of P. gossypiella pheromone; and (Z,Z)-7,11-hexadecadienal, a component of the pheromone of Phyllocnistis citrella, a citrus pest. The compounds were obtained by dynamic headspace and solvent extraction. Samples were analyzed by GC, GC/MS and GC/EAG. The antennas of A. monuste were analyzed by SEM. A male-specific compound has been identified as (E)-3,7-dimethyl-1,3,6-octatriene. In addition, 12 hydrocarbons present in ovipositor, clasper, fore and hind wing extracts incited an electroantegraphic response in males and females. In antennae, Böhm bristles, chaetic, squamiform, basiconic, coeloconic and trichoid sensilla were identified. The key steps of the proposed route are halide-alkyne coupling reactions for chain growth. The intermediate 2-(7-octynyloxy)-tetrahydropyran, common to all routes, was obtained in three steps with 50.5% yield. The 1-bromo-oct-3-yne intermediate was obtained in four steps in 61% yield. The identification of volatiles produced by A. monuste, the behavioral study of this insect, as well as the synthetic route proposed for the preparation of P. gossypiella, S. cerealella and P. citrella pheromones significantly contribute to the development of control and monitoring tools pests sustainably.