Chemical composition and larvicidal activity of essential oils from Zingiber montanum (J. Koenig) Link ex. A. Dietr. against three mosquito vectors / Composición química y actividad larvicida de aceites esenciales de Zingiber montanum (J. Koenig) Link ex. A. Dietr. contra tres vectores de mosquitos

The chemical composition and larvicidal activity of essential oils derived from the leaves and rhizomes of Zingiber montanum (J. Koenig) Link ex. A. Dietr. were reported. The main compounds in the leaf oil were ß-pinene (13.8%), ß-phellandrene (11.3%) and α-pinene (7.3%) while the rhizome oil was dominated by sabinene (41.1%), terpinen-4-ol (22.7%) and (E)-nerolidol (14.3%). The minimum lethal concentration (larvicidal activity) LC50of the rhizome oil at 24 h against Aedes albopictus was 35.17 µg/mL, while LC50 values of 32.20 µg/mL and 31.12 µg/mL were obtained against Aedes aegypti and Culex quinquefasciatus respectively. At 48 h the oil displayed larvicidal action with LC50 values of 23.18 µg/mL, 25.58 µg/mL and 18.99 µg/mL respectively towards Ae. albopictus, Ae. Aegyptiand Cx. quinquefasciatus. The leaf oil did not exhibit significant mortality and larvicidal action. The results indicate the potential of rhizome essential oil of Z. montanumas a source of larvicidal agent.

En el presente trabajo se reportan la composición química y actividad larvicida de los aceites esenciales obtenidos de hojas y rizomas de Zingiber montanum (J. Koenig) Link ex. A. Dietr. Los principales compuestos en el aceite de hojas fueron ß-pineno (13.8%), ß-felandrene (11.3%) y α-pineno (7.3%); mientras que los más abundantes en el aceite de rizomas fueron sabineno (41.1%), terpinen-4-ol (22.7%) y (E)-nerolidol (14.3%). La concentración letal mínima (actividad larvicida) LC50 del aceite de riomas ante Aedes albopictus fue 35.17 µg/mL, mientras que los valores de LC50 de 32.20 µg/mL y 31.12 µg/mL fueron obtenidos ante Aedes aegyptiy Culex quinquefasciatus respectivamente. A las 48 horas, el aceite mostró acción larvicida con valores de LC50 de 23.18 µg/mL, 25.58 µg/mL y 18.99 µg/mL respectivamente, ante Ae. albopictus, Ae. Aegyptiand Cx. quinquefasciatus. El aceite de hojas no mostró mortalidad ni acción larvicida significativa. Los resultados indican el potencial del aceite esencial de rizomas de Z. montanum como una fuente de agentes larvicidas.

Acantholippia deserticola essential oil as a natural pesticide againstagricultural plagues woolly whitefly [Aleurothrixus floccosus (Maskell)],Chilean false red mite (Brevipalpus chilensis Baker) and two-spotted mite(Tetranychus urticae Koch) / Aceite esencial de Acantholippia deserticola como pesticida natural contra plagas agrícolas como mosquita blanca algodonosa [Aleurothrixus floccosus (Maskell)], falsa arañita de la vid (Brevipalpus chilensis Baker) y arañita bimaculada (Tetranychus urticae Koch)

Different concentrations of essential oil obtained from Acantholippia deserticola (Phil.ex F. Phil.) Moldenke were assessed against Chilean agricultural pests like Aleurothrixus floccosus (Maskell), Brevipalpus chilensis Baker, and Tetranychus urticae Koch. Thebioassays were carried out under laboratory conditions and both direct and residual applications were done through Potter precision spraytower test. The oil was obtained by steam distillation containing a rich fraction of alpha and beta-thujones (88.4 percent) and it shows marked toxic effects against pests. Indeed, a mortality of 82 percent and 89 percent was observed in both B. chilensis and T. urticae after 48 h whereas in A. floccosus over 97 percent of mortality was seen after 7 days. These results open the possibility to use essential oil from Acantholippia deserticola as natural pesticide.

Se evaluó el efecto a diferentes concentraciones de una solución de aceite esencial de Acantholippia deserticola sobre plagas agrícolas en Chile, tales como Aleurothrixus floccosus (Maskell), Brevipalpus chilensis Baker y Tetranychus urticae Koch. Los bioensayos fueron realizados mediante una torre de Potter en condiciones de laboratorio y las aplicaciones fueron directas y residuales. El aceite se obtuvo por hidrodestilación, el cual contenía una gran cantidad de alfa and beta-tuyonas (88.4 por ciento), mostrando marcados efectos tóxicos para A. floccosus, con un 97 por ciento de mortalidad después de 7 d y, para B. chilensis, y T. urticae, con una mortalidad de 82 por ciento y 89 por ciento respectivamente, después de 48 h. Estos resultados abren la posibilidad de usar aceite esencial de Acantholippia deserticola como pesticida natural.

Pesticidal and pest repellency activities of a plant derived triterpenoid 2α, 3ß, 21ß, 23, 28-penta hydroxyl 12-oleanene against Tribolium castaneum

BACKGROUND: Tribolium castaneum (Herbst) is a major pest of stored grain-based products, and cause severe damage to cereal grains throughout the world. The present investigation was aimed to determine the pesticidal and pest repellent activities of 2α,3ß,21ß,23,28-penta hydroxyl 12-oleanene against T. castaneum. The compound 2α,3ß,21ß,23,28-penta hydroxyl 12-oleanene is a triterpenoid which was isolated from the roots of Laportea crenulata Gaud. Surface film technique was used for pesticidal screening, whereas, pest repellency property of the triterpenoid was determined by filter paper disc method. RESULTS: At 24 hours of exposure duration, significant mortality records (80% and 86%) were observed at doses 0.88 and 1.77 mg/cm². No significant change in mortality records was observed when duration of exposure was increased up to 48 hours. The triterpenoid showed significant repellency activity at doses 0.47 and 0.94 mg/cm². CONCLUSION: These data suggest that the triterpenoid 2α,3ß,21ß,23,28-penta hydroxyl 12-oleanene possess both pesticidal and pest repellency activities against T. castaneum and can be used in controlling the pest of grain-based products.

Effects of Some Pesticides on Development of Ascaris suum Eggs

To evaluate the effects of pesticides to parasite eggs, Ascaris suum eggs were incubated with 5 different pesticides (1:1,500-1:2,000 dilutions of 2% emamectin benzoate, 5% spinetoram, 5% indoxacarb, 1% deltamethrin, and 5% flufenoxuron; all v/v) at 20degrees C for 6 weeks, and microscopically evaluated the egg survival and development on a weekly basis. The survival rate of A. suum eggs incubated in normal saline (control eggs) was 90+/-3% at 6 weeks. However, the survival rates of eggs treated with pesticides were 75-85% at this time, thus significantly lower than the control value. Larval development in control eggs commenced at 3 weeks, and 73+/-3% of eggs had internal larvae at 6 weeks. Larvae were evident in pesticide-treated eggs at 3-4 weeks, and the proportions of eggs carrying larvae at 6 weeks (36+/-3%-54+/-3%) were significantly lower than that of the control group. Thus, pesticides tested at levels similar to those used in agricultural practices exhibited low-level ovicidal activity and delayed embryogenesis of A. suum eggs, although some differences were evident among the tested pesticides.

Insecticidal activity of three essential oils against two new important soybean pests: Sternechus pinguis (Fabricius) and Rhyssomatus subtilis Fiedler (Coleoptera: Curculionidae) / Actividad insecticida de tres aceites esenciales contra dos nuevas plagas importantes de la soja: Sternechus pinguis (Fabricius) y Rhyssomatus subtilis Fiedler (Coleoptera: Curculionidae)

In the present study, the essential oils from Eucalyptus globulus Labill., Citrus sinensis L. Osbeck and Citrus limon L. were analysed by GC-MS (gas chromatography–mass spectrometry) and evaluated for their toxic effects on Sternechus subsignatus and Rhyssomatus subtilis, two important pest of soybean in South America. Contact toxicity assayed by impregnation on filter paper discs showed that these oils caused significant mortality of the test insects (100 percent of mortality at 5 uL/cm2). Eucalyptus oil (98.9 percent of 1,8-cineole) had the greatest contact toxicity (LD50 = 0.40 and 0.84 uL/cm2 for S. pinguis and R. subtilis, respectively), whereas orange (87.6 percent of limonene) and lemon oils (62.5 and 12.6 percent of limonenen and beta pinene, respectively) were less toxic (LD50 > 1 uL/cm2 for both insects). All the responses were found dose-dependent. Rhyssomatus subtilis was more resistant than Sternechus pinguis to the toxicity of the essential oils studied.

En el presente estudio se analizaron por CG-EM (cromatografía de gases-espectrometría de masas) los aceites esenciales de eucalipto (Eucalyptus globulus Labill.), naranja (Citrus sinensis L. Osbeck) y limón (Citrus limon L) y se evaluaron sus efectos tóxicos contra dos especies de plagas importantes para la soja en Sud América: Sternechus subsignatus y Rhyssomatus subtilis. La toxicidad por contacto, ensayada por discos de papel de filtro impregnados, mostró que estos aceites causaron una mortalidad significativa de los insectos testeados (100 por ciento de mortalidad a 5 uL/cm2). El aceite de eucalipto (98.9 por ciento de 1,8-cineol) presentó la mayor toxicidad por contacto (LD50 = 0.40 y 0.84 uL/cm2 para S. pinguis y R. subtilis, respectivamente), mientras que el aceite de naranja (87.6 por ciento de limoneno) y el de limón (62.5 y 12.6 por ciento de limoneno y beta pineno, respectivamente) fueron menos tóxicos (LD50 > 1 uL/cm2 para ambos insectos). Todas las respuestas fueron dosis dependiente. Rhyssomatus subtilis fue más resistente que Sternechus pinguis a la toxicidad de los aceites esenciales estudiados.

Adulticidal activity of essential oil of Lantana camara leaves against mosquitoes.

Background & objectives: Development of insect resistance to synthetic pesticides, high operational cost and environmental pollution have created the need for developing alternative approaches to control vector-borne diseases. In the present study we have investigated the insecticidal activity of essential oil isolated from the leaves of Lantana camara against mosquito vectors. Methods: Essential oil was isolated from the leaves of L. camara using hydro-distillation method. Bioassay test was carried out by WHO method for determination of adulticidal activity against mosquitoes. Different compounds were identified by gas chromatography-mass spectrometry analysis. Results: LD50 values of the oil were 0.06, 0.05, 0.05, 0.05 and 0.06 mg/cm2 while LD90 values were 0.10, 0.10, 0.09, 0.09 and 0.10 mg/cm2 against Ae. aegypti, Cx. quinquefasciatus, An. culicifacies, An. fluvialitis and An. stephensi respectively. KDT50 of the oil were 20, 18, 15, 12, and 14 min and KDT90 values were 35, 28 25, 18, 23 min against Ae. aegypti, Cx. quinquefasciatus, An. culicifacies, An. fluviatilis and An. stephensi, respectively on 0.208 mg/cm2 impregnated paper. Studies on persistence of essential oil of L. camara on impregnated paper revealed that it has more adulticidal activity for longer period at low storage temperature. Gas chromatographic-mass spectrometric analysis of essential oil showed 45 peaks. Caryophyllene (16.37%), eucalyptol (10.75%), α-humelene (8.22%) and germacrene (7.41%) were present in major amounts and contributed 42.75 per cent of the total constituents. Interpretation &conclusion: Essential oil from the leaves of L. camara possesses adulticidal activity against different mosquito species that could be utilized for development of oil-based insecticide as supplementary to synthetic insecticides.

Evaluación experimental de la eficiencia de una pintura repelente para arañas del género Loxosceles / Effectiveness of a repellent paint against the spider Loxosceles laeta

Background: Loxoscelism is a severe reaction to the bite of the spider Loxosceles laeta. In recent years, a paint with repellent properties has been promoted in the commerce. However, there are no reports of experiments evaluating its effectiveness. Aim: To evaluate experimentally the repellent properties of a paint against Loxosceles laeta. Material and methods: Males, females and nymphs of L laeta were deposited in cockpits that allow the free displacement of the spider. Half of the cockpit was covered with repellent paint. Daily observations during one week, determined how frequently the spiders occupied the space covered with repellent paint. The experiments were run in triplicate. Results: No statisticaldifferences in the occupancy of spaces covered with repellent paint or not covered with it were observed for nymphs (87% and 67%, respectively), males (72% and 77%, respectively) orfemales (91% and 84%, respectively). Conclusions: The tested paint does not have a repellent action against the spider Loxosceles laeta.

Effect of application of different pesticides to soybean on the soil microflora.

Pesticide residues contributing to the contamination of soil may influence microbial population of the soil and in turn fertility of soil. The present paper reports the effect of pesticides applied to soybean i.e. phorate, carbofuran, carbosulfan, thiomethoxam, imidacloprid, chlorpyriphos and monocrotophos on soil microflora. The viable count of rhizobia and phosphate solubilizing bacteria from rhizospheric soil of soybean ranged between 10(7)-10(8) cfu/g soil which was comparable to the count of bacteria from untreated (control) soil. No significant change in the total viable count of any kind of bacteria due to application of pesticides has been found showing their ability to degrade these pesticides.

Histopathological changes in liver, kidney and muscles of pesticides exposed malnourished and diabetic rats.

Histopathological changes were observed in liver, kidney and muscles of normal, protein-malnourished, diabetic as well as both protein-malnourished and diabetic albino rats when exposed to a mixture of monocrotophos, hexachlorocyclohexane and endosulfan at varying intervals. The examination revealed hepatotoxic, nephrotoxic and muscular necrotic effects in pesticides exposed rats. Toxicity was aggravated in protein-malnourished and diabetic animals and more so, if the animals were both diabetic and protein-malnourished.

Inhibition of endocytotic functions in Dictyostelium discoideum treated with a carbamate pesticide.

Administration of a carbamate pesticide carbaryl (1-Naphthyl-N-methyl carbamate) at a concentration of 60 and 100 ppm greatly inhibits the endocytotic functions during growth of the cellular slime mold D. discoideum. The ingestion of fluorescien isothiocynate (FITC) labeled E. coli is reduced between 30 and 40% in the treated cells as compared to controls. Similarly, the uptake of FITC-labeled dextran, which has been used as fluid-phase marker for pinocytosis also show 40-50% inhibition in the treated cells. 3H-leucine uptake and incorporation are also inhibited in the treated cells. SDS-PAGE analysis of cytoskeletal proteins shows a higher actin association with the membrane of treated cells. The results demonstrate the detrimental effects of Carbamate on the soil microbe even at a very low concentration and the efficacy of the slime mold cells as a biosensor for the carbamate-induced cytotoxicity.

Los insecticidas actuales y las perspectivas de los nuevos para el futuro / Prospective and opportunistic analysis on insecticides for the future

La importancia de los pesticidas sintéticos orgánicos continuará creciendo acompañando al aumento de la población mundial y en tanto la proporción de tierra cultivable se mantenga relativamente constante. Los pesticidas permiten salvar el 10 por ciento de los cultivos pero todavía un 37 por ciento se pierden anualmente debido a la acción de las plagas. Se pueden tomar a los insecticidas como modelo para ilustrar la necesidad y posibilidades futuras de agroquímicos más eficaces y seguros para el hombre y su medio. Los insecticidas más importantes en ventas constituyen el 88 por ciento del total y actúan a nivel de sólo cuatro blancos moleculares (targets) nerviosos: Acetilcolinesterasa (AChE) el 62 por ciento; Canales de Sodio-dependientes de voltaje el 18 por ciento; Canales de Cloruro-dependientes de GABA (ácido gama aminobutírico) el 6 por ciento y Receptor Nicotínico para la acetilcolina el 2 por ciento. La utilidad de los tres "targets" primeros, será gradualmente comprometida debido a problemas de resistencia de insectos, en tanto que el receptor nicotínico para acetilcolina se espera que crezca significativamente. Los compuestos que actúan sobre targets No-Nerviosos se convertirán progresivamente en mucho más importantes. Dentro de éstos se incluyen a los desacoplantes de la fosforilación oxidativa, a los inhibidores de la NADH/Ubiquinona óxido-reductasa y a los inhibidores de la ATP-asa, a los reguladores del crecimiento (juvenoides, ecdisona) y a los pesticidas microbianos que actúan en varios nuevos targets. Con un panorama de 300 insecticidas comerciales disponibles en la actualidad y la prospectiva de introducción de no más de 2 ó 3 nuevos compuestos por año en promedio, sería esencial que se hiciera un uso lo más efectivo posible de los insecticidas corrientes. Los compuestos químicos más nuevos son en general más complejos y más costosos comparados con los anteriores, pero se los usa en general a dosis mucho menores resultando una relación costo/efectividad que resulta favorable a la economía minimizando además el impacto ambiental. Los nuevos compuestos son en general activos en contra de las cepas resistentes, integrales además a los programas de M.I.P. (manejo integrado de plagas) y suelen poseer una mínima toxicidad en los mamíferos

A theoretical model describing the influence of diffusion on microbidal action in biofilms

Um dos métodos padröes para avaliar a atividade de um microbicida é a medida da taxa de morte de células sésseis ou em suspensäo (planctônicas). Sabe-se que, na maioria dos casos, células sésseis säo mais resistentes às substâncias inibidoras do que as células planctônicas. Este aumento de resistência pode ser devido à mudança na fisiologia das células ou à falta de penetraçäo do microbicida no biofilme. Um modelo que demonstra a influência da taxa de penetraçäo de microbicidas sobre a morte das células é apresentado. Os cálculos podem ser feitos por computador utilizando-se programas de planilhas eletrônicas. Os resultados mostram que o biofilme reduz a taxa de morte das células, quando a fisiologia microbiana näo é alterada. Pelo modelo, pode-se estimar a concentraçäo de microbicida necessária para matar tanto células sésseis quanto células em suspensäo, no mesmo estado fisiológico, num tempo

Microbial contamination of stored diesel oil in Brasil

As refinarias e sistemas de distribuiçäo tem enfrentado problemas com a contaminaçäo microbiana em óleo diesel armazenado. A atividade microbiana nesses sistemas leva à produçäo de uma biomassa na interface óleo/água, provocando problemas operacionais, como entupimento de filtros, tubulaçöes, alteraçäo na qualidade do combustível. O controle dessa contaminaçäo pode envolver o uso de agentes químicos, como os biocidas. O objetivo desse trabalho foi selecionar biocidas eficientes para o controle de fungos, bactérias aeróbicas e bactérias redutoras de sulfato (BSR), que foram isoladas de óleo diesel comum, urbano e naval, armazenados em tanques de refinaria no Rio Grande do Sul. Dois biocidas (um composto quaternário de amônio e uma mistura de isothiazolona) foram selecionados por apresentarem alta eficácia, em baixas concentraçöes para os principais contaminantes, como fungos do gênero Aspergillus e Hormoconis, BSR e bactérias aeróbias do gênero Pseudomonas e Bacillus

Influence of different pesticide dethamethrin concentrations on the phospholipid composition of carp erythrocyte plasma membrane

In this study, the effect of different concentrations [0.1, 1.2 and 4 ppm] of deltamethrin on the carp erythrocyte plasma membrane was examined following exposure time 48 and 96 hours. The results showed that, the deltamethrin pollutants significantly [P < 0.01] led to decrease of phosphotidyle ethanolamine [PE], phosphoglycerides [PG] and phosphatidic acids [PA] and high concentrations of it led to eliminates the phosphatidic acids and cardiolipin [CL]. Also, deltamethrin pollutant brought about marked difference in the fatty acid patterns of the phospholipids erythrocyte plasma membrane. The increase concentration leads to an increase in the level of saturated fatty acids primarily palmitic [16: 0] and stearic acid [18: 0] as well as in the level of polyunsaturated fatty acids [PUFAs], especially arachidonic acid [20: 4 n-6]. Of monosaturated fatty acids [MUFAs] palmitoleic acid [16: 1 n-7] and oleic acid [18: 1 n-9] did not increased significantly. At the same time the level of omega-3 polyunsaturated fatty acids eicosapentenoic [DHA, 22: 6 n-3], are significantly [P < 0.01] decreased and this makes membrane more rigid and less permeable

Effect of some pesticides/weedicides on cathepsin B activity and lysosomal membrane.

The in vitro inhibitory effects of various weedicides and pesticides on goat brain cathepsin B and their labilizing potency on the lysosomal membrane were quantitated. Endosulfan an organochlorine insecticide inhibited the enzymic activity to approximately 50% at 7 mM concentration followed by methyl parathion, aldrin, melathion and benzene hexachloride (BHC) in that order. Among the weedicides, butachlor was found to be most inhibitory (approximately 50% activity was lost at 6 mM) followed by isoproturone (28%) and anilophos (19%). When the labilizing/stabilizing potency of all these drugs was observed on lysosomal membrane it was found that none of these was capable of stabilizing the membrane. At 40 degrees C and 1 mM drug concentration, aldrin, endosulfan, melathion and anilophos were found to be strong labilizers of the lysosomal membrane. Others like isoproturone, BHC and methyl parathion had moderate labilizing effect. The labilization potency of the drugs was temperature dependent and was less pronounced at 25 degrees C as compared to 40 degrees C.