Time filter

Source Type

Pavela R.,Czech Republic Crop Research Institute
Industrial Crops and Products | Year: 2011

The essential oils from 9 aromatic plants were tested on repellency and mortality of Meligethes aeneus adults. All the tested essential oils caused high mortality of M. aeneus adults in the tarsal tests. The lethal doses after 6h exposure were ranged between 197 and 1508μgcm-2. Essential oils obtained from Carum carvi and Thymus vulgaris were most efficient where LD50 was estimated as 197 and 250μgcm-2, respectively.Repellency declined in all the essential oils as a function of time. The longest persistence time was determined for essences obtained from C. carvi and T. vulgaris where significantly the highest repellent index of 65.6% and 63.8%, respectively, was determined. Repellent index lower than 15% was determined for the remaining essential oils. © 2011 Elsevier B.V.

The efficacy of 30 aromatic compounds and their mutual binary combinations was assessed for acute toxicity against the larvae Culex quinquefasciatus. Based on comparison of the lethal doses, thymol and p-cymene were selected as the most effective (LD50 = 18 and 21 mg L−1, respectively, and LD90 = 25 and 30 mg L−1, respectively). Although the LD50 for terpinolene and trans-anethole was also estimated at 21 mg L−1, their LD90 was significantly higher compared to the substances above (245 and 34 mg L−1, respectively). In total, 435 binary combinations were tested, of which 249 combinations showed a significant synergistic effect, while 74 combinations showed a significant antagonistic effect on mortality. Only nine substances were identified as being able to create a synergistic effect with more than 20 substances: limonene, trans-anethole, 4-allylanisole, carvacrol, isoeugenol, menthone, carvone, borneol, and camphor. The highest synergistic effect on larval mortality was achieved for the combinations: eugenol and isoeugenol, carvone and carvacrol, carvone and 4-allylanisole, carvone and α-terpineol, carvone and menthone, limonene and trans-anethole, limonene and menthone, α-pinene and menthone, β-citronellol and menthone, carvacrol and 4-allylanisole, carvacrol and terpineol, α-terpinene and trans-anethole, camphor and menthone, camphene and menthone, and 4-allylanisole and menthone. Significant differences between achieved mortality and the mutual mixing ratio were found for the five selected binary mixtures that had shown the most significant synergistic effect in the previous tests. The mixture of limonene and trans-anethole showed the highest mortality, with the mixing ratio 1:1; the mixture of eugenol and isoeugenol caused 90.2 % mortality, with the mixing ratio 1:3. One hundred percent mortality was achieved if carvacrol was contained in a mixture with carvone in a ratio >2. After a comparison of all our results, based on our experiments, we can choose two pairs that caused mortality higher than 90 % in concentrations lower than 20 mg L−1: limonene and trans-anethole (with the mixing ratio 1:1), and carvone and carvacrol (with the mixing ratio 1:2–3). The information gained can thus be used in the development of new botanical insecticides based on essential oils (EOs) and particularly in the creation of formulations. © 2015, Springer-Verlag Berlin Heidelberg.

Jarosova J.,Czech Republic Crop Research Institute
BMC plant biology | Year: 2010

BACKGROUND: Reference genes are commonly used as the endogenous normalisation measure for the relative quantification of target genes. The appropriate application of quantitative real-time PCR (RT-qPCR), however, requires the use of reference genes whose level of expression is not affected by the test, by general physiological conditions or by inter-individual variability. For this purpose, seven reference genes were investigated in tissues of the most important cereals (wheat, barley and oats). Titre of Barley yellow dwarf virus (BYDV) was determined in oats using relative quantification with different reference genes and absolute quantification, and the results were compared. RESULTS: The expression of seven potential reference genes was evaluated in tissues of 180 healthy, physiologically stressed and virus-infected cereal plants. These genes were tested by RT-qPCR and ranked according to the stability of their expression using three different methods (two-way ANOVA, GeNorm and NormFinder tools). In most cases, the expression of all genes did not depend on abiotic stress conditions or virus infections. All the genes showed significant differences in expression among plant species. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), beta-tubulin (TUBB) and 18S ribosomal RNA (18S rRNA) always ranked as the three most stable genes. On the other hand, elongation factor-1 alpha (EF1A), eukaryotic initiation factor 4a (EIF4A), and 28S ribosomal RNA (28S rRNA) for barley and oat samples; and alpha-tubulin (TUBA) for wheat samples were consistently ranked as the less reliable controls.The BYDV titre was determined in two oat varieties by RT-qPCR using three different quantification approaches. There were no significant differences between the absolute and relative quantifications, or between quantification using GAPDH + TUBB + TUBA +18S rRNA and EF1A + EIF4A + 28S rRNA. However, there were discrepancies between the results of individual assays. CONCLUSIONS: The geometric average of GAPDH, 18S rRNA and TUBB is suitable for normalisation of BYDV quantification in barley tissues. For wheat and oat samples, a combination of four genes is necessary: GAPDH, 18S rRNA, TUBB and EIF4A for wheat; and GAPDH, 18S rRNA, TUBB and TUBA for oat is recommended.

Muhlbachova G.,Czech Republic Crop Research Institute
Ecological Engineering | Year: 2011

A 40-day incubation experiment was carried out in order to evaluate the microbial activities and heavy metal availability in long-term contaminated arable and grassland soils after addition of EDTA (ethylenediaminetetraacetic acid) or EDDS ([S,S]-ethylenediaminedisuccinic acid). Soils with similar contamination of heavy metal from the vicinity of a lead smelter were used in the experiment. The soil microbial carbon (Cmic) decreased significantly after addition of EDTA in the arable soil (CM1); lesser effects were observed in the grassland soil (CM2). Addition of EDDS caused a decrease of Cmic during the first 10 days of incubation. In the later phases of the experiment, Cmic increased, and even exceeded the amounts found in the control soils. Respiratory activities and metabolic quotients (qCO2) increased after the addition of the chelating agents into the soils. Higher respiratory activities and qCO2 were observed in the EDTA-treated soils. The readily available heavy metal fractions were extracted with NH4NO3 solution. Readily mobilizable heavy metal fractions of Cd, Pb, Zn, and (in part) Cu increased during the first 3-10 days of incubation in the presence of EDTA. The addition of EDDS particularly increased concentrations of available Cu. Significant correlations between NH4NO3-extractable metals, soil respiratory activities, and qCO2 were found in both soil treatments with EDTA and EDDS. This indicates that enhanced metal mobility seriously affects the microbial processes in experimental soils. In addition, the relationships between NH4NO3-extractable Cd, Cu, and the microbial biomass were found in the CM1 soil amended with EDTA. © 2010 Elsevier B.V.

Pavela R.,Czech Republic Crop Research Institute
Industrial Crops and Products | Year: 2013

Acute toxicity of seven naphthoquinones was tested against adults of the house fly (Musca domestica), of which plumbagin was the only one to show sufficient acute toxicity (LD 50=21 and 18μg for females and males, respectively). The efficacy of sublethal doses (LD 30) was determined for plumbagin. Sublethal doses of plumbagin caused significant reductions in the longevity, fecundity and fertility of M. domestica. The treated females oviposited 22.1-30.5 eggs/female on average, while in the variant where treated males coupled with untreated females, the mean number of eggs was 129.3 eggs/female, thus significantly less compared to the control of 224.8 eggs/female. A significantly lower hatching capacity of the larvae (50%) was found in eggs oviposited by treated females compared to the control, where 99% of the larvae hatched.The larvae that did hatch showed reduced vitality compared to the control larvae, manifested by higher mortality during their development and significantly lower natality, which ranged between 44.1 and 57.3% in all treated variants, whereas the natality of the control larvae achieved 76%. Of the tested naphthoquinones, plumbagin exhibits a potential for the development of new botanical insecticides against the house fly. © 2012 Elsevier B.V.

Discover hidden collaborations