Obtenção de óleos essenciais de plantas nativas do Sul do Brasil e avaliação frente a diferentes tipos de pragas

Abstract

The agricultural and beekeeping sector have been looking for alternatives based on plant extracts to combat pests that lead to significant losses in production and consequently an economic impact. The indiscriminate use of synthetic pesticides is one of the reasons that lead to the appearance of resistant pests, in addition to compromising the local fauna and generating chemical residues in the products. Due to this, the demand for natural insecticides has been widely studied and the essential oils (EO), volatile substances produced by the secondary metabolism of plants, are a promising alternative for pest control. The aim of this work is to study the pesticidal activity of Senecio juergensii and Baccharis psiadioides essential oils against pests that affect the agricultural and beekeeping sector: Anticarsia gemmatalis, Rhipicephalus (Boophilus) microplus and Varroa destructor. The EO were obtained by steam distillation and were characterized by Gas Chromatography coupled to Mass Spectrometer (GC/MS). To prevent the rapid degradation and volatility of the EO, they were encapsulated in alginate / chitosan polymers by a method containing steps of o/w emulsification, ionotropic gelation with chitosan and alginate and evaporation of the solvent.The encapsulation efficiency of B. psiadiodies and S. juergensii was 89% ± 4.7 and 86% ± 1.15, respectively.. Free and encapsulated EOs of S. juergensii caused 100% mortality in cattle ticks at 7.5 mg/mL, 75% and 82% mortality in varroa at concentrations of 1% and 30% and 20% mortality in larvae of A. gemmatalis, at 1%. Free and encapsulated OEs of B. psiadiodies also caused 100% mortality in cattle ticks at 7.5 mg/mL, 77.6% and 83.3% mortality in varroas in the concentration of 0.5% and 60% and 40% in A. gemmatalis, at 1%. Mortality of the studied pests increased according to the increase of concentration of the EOs tested and was slower when they were encapsulated, being in agreement with the release tests. The OE of S. juergnesii and B. psiadiodies have shown to be promising in the control of the studied pests.