Induced volatiles in the interaction between soybean (Glycine max) and the Mexican soybean weevil (Rhyssomatus nigerrimus)

The present study analyzed the volatile compounds emitted by Glycine max (cv. FT-Cristalina-RCH) soybean plants: healthy plants and plants damaged mechanically or by the Mexican soybean weevil Rhyssomatus nigerrimus. The SPME method was used to compare the volatile profile of soybean plants in four different conditions. The volatile profile of G. max plants infested by R. nigerrimus was qualitatively and quantitatively different from that of healthy and mechanically damaged plants. Emission of 59 compounds was detected in the four treatments. Of these compounds, 19 were identified by comparison of the Kovats index, mass spectrum and retention times with those of synthetic standards. An increase in concentration of the volatiles (Z)-3-hexenyl acetate and the compound 1-octen-3-ol was observed when the soybean plants were mechanically damaged. The compounds mostly produced by the soybean plant during infestation by male and female R. nigerrimus were 1-octen-3-ol, 6-methyl-5-hepten-2-one, (E)-β-ocimene, salicylaldehyde, unknown 10, linalool, methyl salicylate, (Z)-8-dodecenyl acetate (ester 5), ketone 2 and geranyl acetone. Behavioral effects of the identified compounds during the insect-plant interaction and their conspecifics are discussed.

The connection of inertia rotary moment with the chromatographic retention time in alkanes series. New retention indices.

Earlier it was shown that cause of physicochemical properties oscillation and splitting into even and odd groups in the organic compounds homologous series is the rotational motion energy, determined by the molecule structure. In turn, the organic compound structure can be numerically described or expressed in terms of rotational motion inertia moment. It was logical to assume the correlation between the retention time and rotational motion inertia moment. In order to establish the connection of molecule rotational inertia moment with the chromatographic retention time, a mixture of normal structure alkanes (C6-C17) was experimentally analyzed and corresponding graphs were constructed confirming the assumptions made. A new chromatographic index IJ was proposed, which has advantages over the Kovats index (IK).

Composição química e toxicidade do óleo essencial de eucalipto sobre o ácaro-rajado

The spotted spider mite, Tetranychus urticae Koch, 1836 (Acari: Tetranychidae) is a polyphagous pest which causes extensive damage to Brazilian agriculture. The control of this pest is usually performed by synthetic origin products. Thus, the essential oils with acaricide property can be resources considered as an alternative to control this pest. The objective of this study was to identify the chemical composition and evaluate the fumigation toxicity of Eucalyptus citriodora (Hook.) KD Hill & LAS Johnson essential oil on T. urticae. The essential oil extraction was performed by hydrodistillation, usinga Clevenger type apparatus . The compounds identification was made comparing the obtained mass spectra with the available spectra in the database of the spectral library Willey 330,000 and by the Kovats index (IK), calculated for each compound. Adult female spotted spider mite were subjected to doses of 3.57, 7.14, 10.71, 14.28 and 17.85 μL L-1 of the essential oil air in fumigation chambers during 24, 48 and 72 hours. Subsequently, lethal concentration (LC50) of the essential oil was estimated. Ten compounds were identified, being the citronellal (68.20%) the major compound. The LC50 value observed after 24, 48 and 72 hours of exposure to essential oil were 17.55, 17.00 and 10.50 μL L-1 of air, respectively, and the fecundity of T. urticae females reduced with an increase of the used concentrations.

Chemical Composition and Biological Activity of the Essential Oil of Amomum biflorum

The aim of this study was to investigate the chemical composition and bioactivity of Amomum biflorum Jack harvested in the region of Petchaboon, Thailand. The essential oil of the fresh whole plant obtained by hydrodistillation was analyzed by gas chromatography (GC) (Kovats index) and gas chromatography coupled with mass spectrometry (GC/MS). The average yield of essential oil of A. biflorum was 0.21 ± 0.05 % (w/w). The major chemical constituents were camphor (17.6 %), α-bisabolol (16.0 %), camphene (8.2 %) and α-humulene (5.1 %). The essential oil was active against Staphylococcus aureus (MIC: 30 μ/mL) and had an antioxidant activity with an ORAC index of 23 ± 5 μmol Trolox/mg.

Assessment of Volatile Chemical Composition of the Essential Oil ofJatropha ribifolia(Pohl) Baill by HS-SPME-GC-MS Using Different Fibers

The chemical composition of essential oil and volatile obtained from the roots ofJatropha ribifolia(Pohl) Baill was performed in this work. The Clevenger extractor was utilized in hydrodistillation of oil and chemical composition determined by gas chromatography coupled with mass spectrometry detector (GC-MS). The identification of compounds was confirmed by retention index (Kovats index) obtained from a series of straight chain alkanes (C7–C30) and by comparison with NIST and ADAMS library. A total of 61 compounds were identified in essential oil by GC-MS. The extraction of volatile was performed also by the use of the solid phase microextraction (SPME) with four different fibers. The essential oil extraction was extremely rapid (15 s) to avoid saturation of the fiber and the MS detector. The majority of the composition of essential oil is the terpenes:β-pinene (major compound 9.16%),β-vatirene (8.34%),α-gurjunene (6.98%),α-pinene (6.35%), camphene (4.34%), tricyclene (3.79%) and dehydro aromadendrene (3.52%) it and aldehydes and alcohols. Through the SPME it was possible to determine the nine volatile compounds not identified in oil 2,3,4-trimethyl-2-cyclopenten-1-one,α-phellandrene, 3-carene, trans-p-mentha-2,8-dienol, pinocamphone, D-verbenon, 1,3,3-trimethyl-2-(2-methyl-cyclopropyl)-cyclohexene, 2,4-diisocyanato-1-methylbenzene, and (6-hydroxymethyl-2,3-dimethylehenyl) methanol.