Essential oil composition of Eugenia langsdorffii O. Berg.: relationships between some terpenoids and toxicity against Tetranychus urticae

Abstract

massas) e exibiram alta percentagem de sesquiterpenos. epi-Longipinanol (13,6 ± 0,1%) e g-eudesmol (12,3 ± 0,2%) foram os componentes principais do óleo das folhas, enquanto que 10-epi-g-eudesmol (35,7 ± 0,3%) e 1,10-di-epi-cubenol (15,6 ± 0,3%) foram majoritários no óleo dos frutos. Estudo comparativo da toxicidade por fumigação e contato residual desses óleos foi conduzido. O óleo das folhas (dose letal média, LC 50 = 1,7 µL L -1 de ar) foi 1,7 vezes mais tóxico do que o óleo dos frutos por fumigação, e 1,8 vezes menos tóxico por contato residual. O controle positivo (eugenol) foi muito mais tóxico no bioensaio de fumigação do que os óleos de Eugenia. Entretanto, o efeito de contato residual do óleo dos frutos (LC 50 = 12,25 µL mL -1 ) foi apenas 6,7 vezes menor do que o do eugenol. A função exercida por terpenóides na propriedade acaricida dos óleos de E. langsdorffii também foi discutida.Leaf and fruit essential oils of Eugenia langsdorffii were analyzed by GC-FID (gas chromatography with flame ionization detection) and GC-MS (gas chromatography with mass spectrometric detection), featuring a high percentage of sesquiterpenes. epi-Longipinanol (13.6 ± 0.1%) and g-eudesmol (12.3 ± 0.2%) were the principal components of the leaf oil, whereas 10-epi-g-eudesmol (35.7 ± 0.3%) and 1,10-di-epi-cubennol (15.6 ± 0.3%) were the major constituents of the fruit oil. A comparative study to assess fumigant and residual contact toxicities of the oils was conducted. The leaf oil (lethal concentration average, LC 50 = 1.7 µL L -1 of air) was 1.7 times more toxic than the fruit oil and 1.8 times less toxic by residual contact. The positive control (eugenol) was much more toxic in the fumigation bioassay than Eugenia langsdorffii oils. Nevertheless, the residual contact effect of the fruit oil (LC 50 = 12.25 µL mL -1 ) was just 6.7 times smaller than that of eugenol. The role of terpenoids in the acaricidal property of the E. langsdorffii essential oils was also discussed.

Acaricidal properties of essential oils from agro‐industrial waste products from citric fruit against Tetranychus urticae

“…In the present study, T. urticae was more susceptible to the Citrus oils when using the fumigation method, which is in agreement with data reported by Neves and Camara () and Moraes, da Camara, Santos, and Fagg () for T. urticae exposed to EOs from Lamiaceae and Myrtaceae, respectively. One explanation for the greater toxicity by fumigation is that the effect of the oil is faster through the airways in the form of vapours (Lorini, Krzyzanowski, França‐Neto, Henning, & Henning, ) than by residual contact, as the oil needs to penetrate the tegument layers to have an effect on the pest (Enan, ).…”

Acaricidal properties of the essential oil from Aristolochia trilobata and its major constituents against the two-spotted spider mite (Tetranychus urticae)

“…As occurred with the A. trilobata oil and artificial mixture, the pest was more susceptible to the selected constituents through fumigation than residual contact. Similar results have been described for essential oils from the families Lamiaceae (Neves and da Camara 2016) and Myrtaceae (Moraes et al 2012). One explanation for the greater toxicity achieved with fumigation is the acute toxic effect on nerve cells promoted by the penetration of the oil vapors through the airways of the arthropod (Lorini et al 2015), whereas penetration with the residual contact method is limited by barriers of the integumental, which metabolize and neutralize the acaricidal toxins prior to reaching the target site (Enan 2001).…”

Chemical composition and acaricidal activity of the essential oils from Vitex agnus-castus L. (Verbenaceae) and selected monoterpenes

“…The oils from V. agnus-castus were analyzed using gas chromatography (GC-FID) and chromatography-mass spectrometry (GC-MS) and identification of the components was performed using the same methodology described in previous reports by our research team (Moraes et al 2012, Araújo et al 2012. The identification of the components was based on the GC-FID retention indices with reference to a homologous series of C 11 -C 24 n-alkanes and by computer matching against the mass spectral library of the GC-MS data system (NIST 98 and willey) and co-injection with authentic standards (Adams 2007).…”