Óleo essencial de capim-limão como protetor de sementes e grãos armazenados: uma abordagem da biologia química e molecular ao manejo agroecológico do carucho do feijão-caupi

Abstract

ALVES, Marcela de Souza. Lemongrass Essential Oil as a Protector of Stored Seeds and Grains: A Chemical and Molecular Biology Approach to the Agroecological Management of Cowpea Beetle. 129p. Thesis (Doctorate in Chemistry, area of concentration in Biological Chemistry). Federal Rural University of Rio de Janeiro, Seropédica, RJ, 2021. Essential oils are promising for protecting seeds and grains from infestation by insect pests and phytopathogenic fungi. In this context, the present study had the following objectives: to study the effects of the essential oil of Cymbopongon citratus (lemon grass) and citral on the stages of the insect life cycle, to investigate the following effects of the essential oil: on the metabolism of females copulates of C. maculatus, on seed protection as a function of time, on bean (Vigna unguiculata) seed germination, on fungal development under storage conditions and on cell viability/toxicity in yeast (Saccharomyces cerevisiae), eukaryotic cell model. For this, the chemical characterization of lemongrass essential oil was carried out, where a chemical profile rich in monoterpenes was observed, with the majority components neral (34.63%) and geranial (42.80%) that form the isomer citral, in which cowpea seeds were washed with essential oil and stored for up to 180 days, and it was found that seeds coated with the essential oil showed citral residues on their surface and protection against weevils for up to 90 days of storage. A toxic effect of essential oil fumigation was observed on insect mortality of 61.43% at a concentration of 0.92mg/cm³ and inhibition of their life cycle. In the metabolic profile of mated females, there was a predominance of sugars (trehalose and glucose) and amino acids (proline and alanine), in the control group, however, in females exposed to essential oil, increased levels of glycerol and decreased relative expression were observed. of the enzymes hexokinase, lactate dehydrogenase and malate dehydrogenase. The essential oil showed toxicity on the growth of fungi in the storage condition. Cell viability in a eukaryotic cell model, the yeast of S. cerevisiae, was observed in up to 3 hours of exposure to the essential oil. There was no allelopathic effect of the essential oil on the germination of cowpea seeds. Based on the tests carried out, it is concluded that lemongrass essential oil has the potential to develop strategies to protect grains and seeds to replace traditional control, especially in serving the organic seed production sector