The thrips, Frankliniella schultzei, and green peach aphid, Myzus persicae, cause direct damage to plants of economic importance and transmit phytoviruses, causing large economic losses. Chemical ...constituents of essential oils present a wide range of biological activities. The aim of this work was to evaluate insecticidal activity of essential oil from citronella grass, Cymbopogon winterianus, on F. schultzei and M. persicae. This essential oil was obtained by steam distillation and components were identified by GC/FID and GC/MS. A Potter spray tower was used to spray insects with the essential oil. The major constituents are geraniol (28.62%), citronellal (23.62%) and citronellol (17.10%). Essential oil of C. winterianus at 1% (w v-1) causes mortality in F. schultzei and M. persicae at 34.3% and 96.9%, respectively. The LC50 value for M. persicae was 0.36% and LC90 0.66%. Thus, citronella grass essential oil at 1% (w v-1) is more toxic to M. persicae than F. schultzei. This essential oil shows promise for developing pesticides to manage M. persicae.
O tripes, Frankliniella schultzei, e o pulgão-verde, Myzus persicae, além de causarem danos diretos a plantas de importância econômica, também são importantes transmissores de fitoviroses, acarretando grandes perdas econômicas. Os constituintes químicos dos óleos essenciais têm sido cada vez mais estudados, pois apresentam uma ampla gama de atividades biológicas. Neste trabalho, objetivou-se avaliar a atividade inseticida do óleo essencial de capim-citronela, Cymbopogon winterianus, sobre F. schultzei e M. persicae. O óleo essencial foi obtido por hidrodestilação e a identificação dos seus componentes foi realizada por CG/DIC e CG/EM. Uma torre de Potter foi utilizada para pulverizar os insetos com óleo essencial. Os componentes majoritários encontrados são geraniol (28,62%), citronelal (23,62%) e citronelol (17,10%). O óleo essencial de C. winterianus a 1% (m v-1) causa mortalidade de F. schultzei e M. persicae em 34,3% e 96,9%, respectivamente. O valor estimado de CL50 para M. persicae foi 0,36% e CL90 de 0,66%. Assim, o óleo essencial de capim-citronela a 1% (m v-1) é mais tóxico para M. persicae do que para F. schultzei. Este óleo essencial mostra-se promissor para o desenvolvimento de inseticidas para o manejo de M. persicae.
ABSTRACT The insect Dysmicoccus brevipes (Hemiptera: Pseudococcidae) has been reported as an important pest for several crops, especially coffee. The citrus essential oils can be obtained as ...by-products of the citrus-processing industry and have been tested as an alternative to control different insect groups. Therefore, the objective of this work was to determine the chemical composition and evaluate the toxicity of commercial sweet orange (Citrus sinensis), bitter orange (Citrus aurantium) and Sicilian lemon (Citrus limon) essential oils and pure monoterpene D-limonene on D. brevipes. The essential oils were analyzed by gas chromatography. Two bioassays were conducted; the first assessing the insect mortality in all oils and the second assessing the lethal concentrations (LC50 and LC95) of the most effective oils. The main components of the oils were D-limonene (83.33%) and Linalool (8.91%) (sweet orange); D-limonene (78.53%) and γ-terpinene (12.65%) (bitter orange); D-limonene (59.78%), beta-pinene (14.71%) and γ-terpinene (10.19%) (Sicilian lemon) and the compound D-limonene had 97% of purity. The highest mortalities were found with the use of the Sicilian lemon (98.68%) and sweet orange (94.11%)oils. The sweet orange oil presented lethal concentrations at 2.21% (LC50) and 3.55% (LC95), and the Sicilian lemon oil at 0.72% (LC50) and 2.91% (LC95). The main component of the sweet orange and Sicilian lemon essential oils was the D-limonene, and the Sicilian lemon oil was most effective oil to control D. brevipes.
RESUMO O inseto Dysmicoccus brevipes (Hemiptera: Pseudococcidae) tem sido relatado como uma praga de importância para diversas culturas, em especial a cafeicultura. Os óleos essenciais cítricos podem ser obtidos como subprodutos da indústria de sucos e vem sendo testados como alternativa no controle de diferentes grupos de insetos. Logo, objetivou-se neste trabalho determinar a composição química e avaliar a toxicidade de óleos essenciais comerciais de laranja doce (Citrus sinensis), laranja amarga (Citrus aurantium), limão Siciliano (Citrus limon) e do monoterpeno D-limoneno sobre a D. brevipes. Os óleos essenciais foram analisados por cromatografia gasosa. Foram realizados dois bioensaios. O primeiro para avaliar a mortalidade em todos os óleos e o segundo para avaliar as concentrações letais (CL50 e CL95) dos óleos mais efetivos. Os constituintes majoritários do óleo de laranja doce foram o D-limoneno (83,33%); linalol (8,91%), do óleo de laranja amarga foram o D-limoneno (78,53%); γ-terpineno (12,65%), do óleo de limão Siciliano foram o D-limoneno (59,78%); beta-pineno (14,71%); γ-terpineno (10,19%) e o composto D-limoneno (97% de pureza). O óleo de limão Siciliano e laranja doce foram os que apresentaram maior percentual de mortalidade, sendo 98,68%, 94,11%.As CL50 e CL95, para o óleo de laranja doce foram de 2,21% e 3,55% e para o óleo de limão Siciliano foram de 0,72% e 2,91%, respectivamente. Portanto, o composto majoritário presente na composição química do óleo essencial de laranja doce e do limão Siciliano foi o D-limoneno e o mais efetivo sobre D. brevipes foio óleo de limão Siciliano.
The use of Chenopodium ambrosioides L. has shown to be promising in the management of gastrointestinal nematodes. The objective of this study was to quantitate the yield and characterize the chemical ...composition of the essential oil of C. ambrosioides, as well as to evaluate the in vitro effect of the ethanolic extract and the essential oil in L3 of Ancylostoma spp. and the in vivo effect(s) of the essential oil in dogs. The effects of the ethanol extract and essential oil on Ancylostoma spp. were evaluated in vitro by exposing larvae to the extract at concentrations ranging from 0.005 g mL-1 to 0.2 g mL-1 and to essential oil at concentrations of 50, 100, and 150 ?L mL-1. For the in vivo test, 26 healthy dogs, naturally infected by Ancylostoma spp., were divided into three groups: F1 - cookies were administered without active principle; F2 - herbal cookies containing 37.5 ?L g-1 essential oil of C. ambrosioides L.; F3 - cookies plus a commercial formulation containing febantel, pyrantel, praziquantel, and ivermectin. Complete blood counts and serum biochemistry for AST, ALT, AF, urea, creatinine, total protein, and albumin were performed. The yield of the essential oil was 0.3% m v-1, and its major components included ?-terpinene (1.24%), p-cymene (4.83%), and ascaridol Z (87%) and E (5.04%) isomers. The concentrations of C. ambrosioides L. ethanol extract used were ineffective against Ancylostoma spp. larvae. The essential oil at a concentration of 150 ?L mL-1 was effective against L3 larvae. In the in vivo study in dogs, the herbal cookies containing C. ambrosioides L essential oil reduced the number of eggs per gram of feces.
Lepidaploa rufogrisea is a promising candidate in the search of natural herbicides, with compounds (sesquiterpene lactones-glaucolide B) which have been reported to present with phytotoxic potential ...against weeds. Thus, this work aimed to accomplish the phytochemical investigation of L. rufogrisea as well as the evaluation of its biological effects on the plant model Lactuca sativa. To this end, different extracts (aqueous, hydroalcoholic and hexane) of L. rufogrisea at different concentrations 0.25, 0.5, 1.0, 2.0 and 4.0 % (m/v) were evaluated from macroscopic (percentage of germinated seeds, germination speed index and root length) and microscopic analysis (mitotic index and cell cycle alterations) in plantlets (150 per treatment) and meristematic cells (10 000 per treatment) of L. sativa var. Cristina. The extracts decreased the germination speed index and also the root growth of L. sativa plantlets. Cell proliferation was not significantly affected by the extracts. However, some chromosome and nuclear alterations in the mitotic spindle were observed, due to the interference of allelochemicals present in L. rufogrisea. Moreover, the plant model L. sativa demonstrated to be efficient for this kind of studies.
Plant extracts have been studied as a promising source of natural insecticides. This study assessed the effect of the ethanol extract of Cymbopogon winterianus Jowitt (citronella grass) in comparison ...with an insecticide containing azadirachtin (ICA) on mortality and number of eggs of Tetranychus urticae Koch (Acari: Tetranychidae) in laboratory conditions. For the tests, the mites were sprayed with the aid of a Potter spray tower. To assess the mortality of females, LC50 value for extract of citronella grass and ICA was, respectively, 2.63 and 2.83%. With respect to the number of eggs, the greatest reduction was observed at a concentration of 5% for the evaluation period of 120h, both for the extract of citronella grass (86%) and for ICA (81%). These results suggest the potential of the ethanol extract of citronella grass to control of T. urticae. However, experiments, under field conditions, involving other populations of T. urticae should be performed to verify the efficacy of this extract as an alternative to be used in pest management programs
Extratos vegetais têm sido estudados como uma fonte promissora de inseticidas naturais. Neste trabalho, foi avaliado o efeito do extrato etanólico de Cymbopogon winterianus Jowitt (capim-citronela) em comparação com um inseticida contendo azadiractina (ICA) sobre a mortalidade e o número de ovos de Tetranychus urticae Koch (Acari: Tetranychidae), em condições de laboratório. Para a realização dos ensaios, os ácaros foram pulverizados com o auxílio da torre de Potter. Para o teste de avaliação da mortalidade de fêmeas, a CL50, para o extrato de capim-citronela e ICA, foi, respectivamente, 2,63 e 2,83%. Em relação ao número de ovos, a maior redução foi observada na concentração de 5% no intervalo de avaliação de 120h, tanto para o extrato de capim-citronela (86%) quanto para o ICA (81%). Estes resultados sugerem que o extrato etanólico de capim-citronela apresenta potencial para ser utilizado no controle de T. urticae. Entretanto, ainda devem ser realizados experimentos em condições de campo, envolvendo outras populações de T. urticae, para averiguar a eficácia deste extrato como alternativa a ser utilizada em programas de manejo da praga
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Phytovirus vectors Frankliniella schultzei (Trybom, 1920) (Thysanoptera: Thripidae) and Myzus persicae (Sulzer, 1776) (Hemiptera: Aphididae) feed on crops of great economic importance brings large ...economic losses worldwide to cultivated species such as tomato and cotton. F. schultzei transmits Tospovirus, Groundnut ring spot virus (GRSV) and Tomato spotted wilt virus (TSWV) to tomato plants and M. persicae transmits Potato virus Y (PVY), Tomato yellow top virus (ToYTV) and Tomato bottom yellow leaf virus (TBYLV) to tomato crops. Chemical constituents of essential oils have been increasingly studied because they present a wide range of biological activities. The aim of this work was to characterize Cymbopogon citratus essential oil and evaluate its potential insecticide activity against F. schultzei and M. persicae. The essential oil was obtained from fresh leaves by hydrodistillation using a Clevenger apparatus. Its yield (1.04%) was determined relative to the dry mass of the plant. Qualitative analysis was performed by gas chromatography coupled to mass spectrometry and chemical constituent content was determined by gas chromatography with a flame ionization detector. Nine compounds were identified, with geranial (49.98%) and neral (37.78%) being the major components. The insects were sprayed with C. citratus essential oil at different concentrations using a Potter tower. The LC50 values for M. persicae and F. schultzei were 0.28% and 1.49%, respectively. Essential oil from C. citratus is a promising natural alternative for developing pesticides to manage M. persicae.
Tetranychus urticae Koch (1836) (Acari: Tetranychidae), conhecido como ácaro rajado, é uma praga que pode reduzir a produção de frutos do morangueiro em até 80%. O controle desta praga por meio de ...acaricidas sintéticos tem proporcionado à destruição de organismos benéficos e o desenvolvimento de populações resistentes. Como alternativa ao controle tradicional, este trabalho teve como objetivo avaliar os efeitos do extrato de Sapindus saponaria e de solução sabão sobre a oviposição e mortalidade de fêmeas de T. urticae. Os ácaros foram pulverizados, com auxílio da Torre de Potter, usando formulações do extrato/solução sabão a 1, 2, 3, 4, 5% (m/v) e avaliados em 24, 72 e 120h. Verificou-se que o extrato de S. saponaria apresentou maior eficiência (CL50, 1,18%) do que a solução sabão (CL50, 1,31%). Em relação à atividade ovicida, o maior efeito foi observado com a formulação a 5% (m/v) após 120h, tanto para o extrato de S. saponaria (60,9%) quanto para solução sabão (84%). Os resultados observados, em condições de laboratório, são favoráveis à utilização do extrato de S. saponaria e de solução sabão no controle de T. urticae em programas de manejo fitossanitário para a cultura do morango.
Os óleos essenciais constituem um tipo de metabólito secundário de grande importância econômica e estão sendo cada vez mais estudados e utilizados como potentes inibidores de sementes e do ...crescimento de diversas plantas. O presente trabalho teve por objetivo a análise química qualitativa e quantitativa bem como a avaliação da atividade alelopática do óleo essencial extraído das folhas frescas de eucalipto (Eucalyptus citriodora) sobre a germinação e o desenvolvimento radicular das sementes de sorgo (Sorghum bicolor L.) e pepino (Cucumis sativus L.), cultivados em placa de Petri. O óleo essencial foi obtido por hidrodestilação, utilizando um aparelho tipo Clevenger, e analisado por cromatografia em fase gasosa com detector de ionização de chama e espectrometria de massas. Foi possível identificar doze constituintes químicos correspondendo a 97,69%, com predominância dos monoterpenos oxigenados citronelal (64,92%) e iso-isopulegol (10,20%) e do citronelol (8,25%). Os ensaios biológicos utilizando o óleo essencial mostraram que o mesmo apresenta efeito alelopático, prejudicando a germinação e o desenvolvimento da radícula das sementes de sorgo e pepino, sendo a redução da germinação mais pronunciada no sorgo, e que o aumento da concentração do óleo leva a uma redução linear na capacidade germinativa e no desenvolvimento da radícula.
The formation of an urban heat island (UHI) is one of the most common impacts of the urbanization process. To mitigate the effects of UHI, the planning of urban forests (e.g., creation of parks, ...forests and afforestation streets) has been the major tool applied in this context. Thus, the aim of this study is to evaluate the spatial and temporal distribution of heat islands in Vila Velha, ES, Brazil using the mono-window algorithm. The study followed these methodological steps: 1) mapping of urban green areas through a photointerpretation screen; 2) application of the mono-window algorithm to obtain the spatial and temporal patterns of land surface temperature (LST); 3) correlation between LST and the normalized difference vegetation index (NDVI) and normalized difference build-up index (NDBI); 4) application of ecological evaluation index. The results showed that the mean values of LST in urban areas were at least 2.34 to 7.19°C higher than undeveloped areas. Moreover, the positive correlation between LST and NDBI showed an amplifying effect of the developed areas for UHI, while areas with a predominance of vegetation attenuated the effect of UHI. Urban centers, clustered in some parts of the city, received the worst ecological assessment index. Finally, the adoption of measures to guide the urban forest planning within urban centers is necessary to mitigate the effect of heat islands and provide thermal comfort in urban areas.
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•Urbanization resulting in higher radiation absorption, causing the effect of UHI•Green areas attenuate the effect of UHI, provide thermal comfort.•Identification of UHI as indicators for urban management and planning•The methodology applied proved to be appropriate to identify the UHI.
Concerned about weed infestation, a major threat to food production and herbicide resistance that interferes in the mechanism of action of the main herbicides, we have synthesized eight isatin ...derivatives using the “Click Chemistry” approach through copper-catalyzed azide–alkyne cycloadditions (CuAAC). Sixteen isatin derivatives were evaluated for their phytotoxic activity against the seed culture of the model plants, Lactuca sativa and Allium cepa. Six of them showed phytotoxic activity similar to the positive control, trifluralin. Hypocotyl length measurement analysis in L. sativa revealed that triazole derivative 8 is more active than trifluralin. For A. cepa, root length measurement analyses revealed that 3, 10, 14, 16, and 17 were similar to the positive control trifluralin. Three-dimensional quantitative structure–activity relationship (3D-QSAR) comparative molecular field analysis (CoMFA) model construction using the acetolactate synthase (ALS) crystallographic structure displayed pk i values of predicted inhibitory activity and contour maps revealing sterically bulky groups for 11, the CF3 group in ortho, and for 17, Br in ortho, favoring the inhibitory ALS activity.
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