VARIACIÓN EN LA COMPOSICIÓN DE ÁCIDOS CRASOS SEMINALES EN ALGUNAS ESPECIES DE SOLANUM(SOLANACEAE)

The fatty acids of seed oils of 16 species (65 populations) of Solanum growning in Argentina were studied by gas-liquid chromatography. A high level of 18:2 and 18:l were found in al1 species studied. Some chemosystematic considerations are made.Se ha estudiado por cromatografia gas-líquido la composición de los ácidos grasos en el aceite seminal de 16 especies (65 poblaciones) de Solanum que crecen en Argentina. En todas las entidades analizadas se ha encontrado un alto contenido de los ácidos grasos 18:2 y 18:l. Se realizan algunos comentarios quimiotaxonómicos

Pulsed laser induced switching of birefringence in nematic phase of photochromic molecules

Fast and dynamic switching of liquid-crystalline photochromic system birefringence induced by pulsed laser has been observed. The system consisted of photochromic molecules of 4-heptyl-4-methoxyazobenzene showing liquid-crystalline nematic state close to the room temperature. Experiment of dynamic birefringence switching was done in optical Kerr effect (OKE) set-up, where for the sample excitation picosecond pulsed laser was used. Simultaneously, He-Ne laser was served as a probe beam source. Measurements were done for different voltages applied to the sample. Rise time constant was in the range of microseconds. Full reversibility of the OKE signal was observed. (C) 2011 American Institute of Physics. [doi:10.1063/1.3559613

Influence of temperature on dynamics of birefringence switching in photochromic nematic phase

We present results of dynamic and fast switching of birefringence in a photochromic liquid-crystalline system as a function of the sample temperature. The system consists of photochromic molecules of 4-heptyl-4-methoxyazobenzene showing a liquid-crystalline nematic state close to room temperature. An experiment of dynamic birefringence switching was done in optical Kerr-effect set-up, where for the sample excitation, a picosecond-pulsed laser was used. Measurements were done for different temperatures of the sample in the liquid-crystalline nematic phase. We have proposed a mathematical model of dynamic, fast, and fully reversible birefringence changes. Theoretical estimations and experimental results have shown very good agreement. (C) 2011 American Institute of Physics. [doi:10.1063/1.3665123

Efficacy of selected volatile compounds for organic vine mealybug control

Planococcus ficus (Signoret) (Hemiptera: Pseudo-coccidae) constitutes a high impact pest in vineyards. Synthetic insecticides are inefficient to control the mealybug population and they affect human health and the environment. The insecticidal properties of eight volatile compounds against vine mealybugs and their grapevine leaf phytotoxicity in laboratory conditions were evaluated. 2-decanone, 3-decanone, α-methyl cinnamaldehyde and cinnamaldehyde produced a higher percentage of mealybug mortality in relation to control at a fumigant dose of 300 µL·L-1 air. The 3-octanone, cinnamyl chloride, 1-octen-3-ol and 3-octanol were not effective against P. ficus. Cinnamaldehyde and α-methyl cinnamaldehyde produced a low acetylcholinesterase inhibition (IC50= 2.67 µL·L-1 and 9.10 µL·L-1, respectively), whereas 2-decanone and 3-decanone did not cause enzyme inhibition. Cinnamaldehyde was not phytotoxic for grapevine leaves; therefore, this compound was selected for a contact application to improve its effectiveness, resulting in a LC50 of 394.36 µL·L-1 solution. The results demonstrated the potential of cinnamaldehyde to be developed as a non-phytotoxic natural insecticide for the control of vine mealybugs in vineyards

Laboratory evaluation of insecticidal activity of plant essential oils against the vine mealybug, Planococcus ficus

Planococcus ficus is a principal mealybug pest of vineyards worldwide. Minthostachys verticillata and Eucalyptus globulus essential oils (EO) were evaluated as insecticidal products on P. ficus, and the main components of M. verticillata and E. globulus EO were also tested as insecticidal compounds against vine mealybug females under laboratory conditions. The results revealed that M. verticillata EO was more toxic than E. globulus EO, while pulegone (LC50 39.60 µL/L) was more toxic than the other constituents of the EO studied. Menthofuran, an oxidation product of pulegone by cytochrome P450 enzymes, showed an LC50 value of 63.97 µL/L. Thus, the mechanism of insect detoxification did not reduce the toxic potential of the pulegone. In addition, 1,8-cineole had a higher insecticidal property than its isomer 1,4-cineole. Our studies suggest that the pulegone can be a useful fumigant botanical insecticide to protect crops against vine mealybug attacks

Fumigant toxicity from five essential oils rich in ketones against Sitophilus zeamais (Motschulsky)

Essential oils (EOs) and individual compounds act as fumigants against insects found in stored products. In fumigant assays, Sitophilus zeamais Motschulsky adults were treated with essential oils derived from Aphyllocladus decussatus Hieron, Aloysia polystachya Griseb, Minthostachys verticillata Griseb Epling and Tagetes minuta L , which are rich in ketones and their major components: α- thujone, R-carvone, S-carvone, (-) menthone, R (+) pulegone and E-Z- ocimenone. M. verticillata oil was the most toxic ( LC50: 116.6 µl /L air) characterized by a high percentage of menthone (40.1%) and pulegone (43.7%). All ketones showed insecticidal activity against S. zeamais. However, pulegone (LC50: 11.8 µl/L air), R- carvone (LC50: 17.5 µl/L air), S-carvone (LC50: 28.1 µl/L air) and E-Z-ocimenone (LC50: 42.3 µl/L air) were the most toxic. These ketones are a,b-unsaturated carbonyl. This feature could play a fundamental role in the increase of insecticidal activity against S. zeamais.Fil: Herrera, J. M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentina. Universidad Nacional de Córdoba; ArgentinaFil: Zunino, María Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentina. Universidad Nacional de Córdoba; ArgentinaFil: Massuh, Yamile. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentina. Universidad Nacional de Córdoba; ArgentinaFil: Pizzollito, R. P.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentina. Universidad Nacional de Córdoba; ArgentinaFil: Dambolena, Jose Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentina. Universidad Nacional de Córdoba; ArgentinaFil: Gañan, Nicolas Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (i); ArgentinaFil: Zygadlo, Julio Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentina. Universidad Nacional de Córdoba; Argentin

Efectividad del aceite esencial de orégano mexicano de República Dominicana (Lippia graveolens) contra plagas del maíz (Sitophilus zeamais y Fusarium verticillioides)

The insecticidal and antifungal properties of Mexican oregano (Lippia graveolens) essential oil from the Dominican Republic were investigated under laboratory conditions against two main pests of stored grains: Sitophilus zeamais and Fusarium verticillioides. Although oregano essential oil at 600 ?l/l air did not result in a significant mortality of S. zeamais after 24 hours of exposure by fumigation, this essential oil was a powerful acetylcholinesterase (AChE) inhibitor in vitro. One of the main components of oregano essential oil, p-cymene, presented fumigant toxicity and AChE inhibition activity against the maize weevil. The L. graveolens essential oil antifungal activity against F. verticillioides was evaluated at 50, 100 and 200 ?l/l, and it was found that growth parameters were affected by the presence of oregano essential oil in the media, whereas FB1 production was not inhibited. The results demonstrate that oregano essential oil and p-cymene can be used as alternatives to synthetic pesticides against F. verticillioides and S. zeamais, respectively.Se estudiaron en condiciones de laboratorio las propiedades insecticidas y fungicidas del aceite esencial de orégano mexicano (Lippia graveolens) de República Dominicana contra dos plagas principales de granos almacenados: Sitophilus zeamais y Fusarium verticillioides. Aunque el aceite esencial de orégano a 600 ?l/l de aire no resultó en una mortalidad significativa de S. zeamais después de 24 horas de exposición a la fumigación, fue un potente inhibidor de la acetilcolinesterasa (AChE) in vitro. El p-cimeno, uno de los principales componentes del aceite esencial, presentó actividad fumigante y de inhibición de la AChE contra el gorgojo del maíz. Además se evaluó la actividad antifúngica frente a F. verticillioides a 50, 100 y 200 ?l/l y se encontró que los parámetros de crecimiento del hongo fueron afectados por la presencia del aceite esencial de orégano en el medio, mientras que la producción de fumonisina B1 (FB1) no se inhibió. Los resultados demuestran que el aceite esencial de orégano y el p-cimeno se pueden usar como alternativas a los pesticidas sintéticos contra F. verticillioides y S. zeamais, respectivamente

Bioactivity of Argentinean Essential Oils Against Permethrin-Resistant Head Lice, Pediculus humanus capitis

Infestation with the head louse, Pediculus humanus capitis De Geer (Phthiraptera: Pediculidae), is one of the most common parasitic infestation of humans worldwide. Traditionally, the main treatment for control of head lice is chemical control that is based in a wide variety of neurotoxic synthetic insecticides. The repeated overuse of these products has resulted in the selection of resistant populations of head lice. Thus, plant-derived insecticides, such as the essential oils seem to be good viable alternatives as some have low toxicity to mammals and are biodegradable. We determined the insecticidal activity of 25 essential oils belonging to several botanical families present in Argentina against permethrin-resistant head lice. Significant differences in fumigant activity against head lice were found among the essential oils from the native and exotic plant species. The most effective essential oils were Cinnamomum porphyrium, followed by Aloysia citriodora (chemotype 2) and Myrcianthes pseudomato, with KT50 values of 1.12, 3.02 and 4.09; respectively. The results indicate that these essential oils are effective and could be incorporated into pediculicide formulations to control head lice infestations once proper formulation and toxicological tests are performed