Óleos essenciais de Illicium verum, Myristica fragrans e Schinus molle: caracterização química, atividade inibitória enzimática e avaliação dos efeitos letais e subletais sobre Drosophila suzukii

Abstract

Drosophila suzukii is an emerging insect pest capable of causing severe economic damage and its control is usually done with synthetic insecticides. Essential oils represent an alternative source for pest control, being an environmentally friendly and sustainable option. Such activity can occur by neurotoxic action, in addition, they can promote appreciable sublethal effects such as the reduction of oviposition, morphological changes and repellent effect. The objectives of this study were to determine the extraction yield of the essential oils of Illicium verum, Myristica fragrans and Schinus molle; perform their chemical characterization; evaluate the inhibitory activity of the acetylcholinesterase enzyme; to determine the toxicity of these oils on D. suzukii and, finally, to evaluate the sublethal effects of I. verum oil on the morphology of females of this insect species. The extraction yield was 2,49% for I. verum, 5.14% for M. fragrans and 1.08% for S. molle. The major compounds present in essential oils were (E)-anethole (99.61%) in I. verum oil; for M. fragrans were sabinene (27.39%), limonene (25.51%), β-pinene (17.95%) and α-pinene (17.77%) and for S. molle they were limonene (25.55%), bicyclogermacrene (22.93%), sabinene (19.66%) and trans-β-karyophylene (12.74%). The values for Inhibition Concentration for 50% (IC50) of the enzyme acetylcholinesterase were 0.117; 0.057 and 0.047 μg mL-1 for I. verum, M. fragrans and S. molle, respectively. The toxicological data revealed that the Lethal Concentration for 50% of the individuals (LC50) of D. suzukii was 1.9; 26.5 and 58.7 μL mL-1 for I. verum, M. fragrans and S. molle, respectively. Histological and histochemical analyzes revealed changes in carbohydrate content, thickness of muscle fibers, area of lipid droplet in the fat body and epithelial thickness of the midgut of insects exposed to the oil of I. verum. All the oils satisfactorily inhibited the enzyme acetylcholinesterase and showed appreciable toxicity on D. suzukii. Especially the oil of I. verum, which had a very low LC50 and caused severe morphological changes in insects, making it a promising alternative to the control of insect pests.