EFFICACY EVALUATION OF INSECTICIDES ON LARVAE OF THE TOMATO BORER TUTA ABSOLUTA, MEYRICK (LEPIDOPTERA: GELECHIIDAE) UNDER LABORATORY CONDITIONS

Abstract The tomato borer Tuta absoluta (Meyrikc

Effect of the Predecessor and the Nitrogen Rate on Productivity and Essential Oil Content of Coriander (Coriandrum sativum L.) in Southeast Bulgaria

Received: May 31st, 2022 ; Accepted: August 13th, 2022 ; Published: September 19th, 2022 ; Correspondence: [email protected] (Coriandrum sativum L.) is one of the most important essential oil crops on a global scale. Coriander productivity is determined by the genotype, the environmental factors, as well the agronomic practices. A field experiment was conducted in Southeast Bulgaria during three vegetation seasons (2015, 2016, and 2017). The present study aimed at analysing the influence of two crop predecessors (winter wheat and sunflower) and four nitrogen (N) levels (0, 40, 80, and 120 kg ha-1 ). Productivity elements, seed yield, and seed essential oil content of coriander (cv. Mesten drebnoploden) were under evaluation. The results obtained showed that winter wheat was a more suitable predecessor of coriander in comparison to sunflower. The highest results regarding the number of umbels per plant, the umbel’s diameter, the number of umbellets per umbel, the number of seeds per umbel, the seed weight per plant, the 1,000 seed mass, as well as the seed yield for the rate of 80 kg ha-1 of N were recorded. The highest essential oil content after applying 120 kg ha-1 of N was established. Increasing the N level from 0 to 120 kg ha-1 led to a positive and significant effect on essential oil yield. No significant differences between the N rates of 80 and 120 kg ha-1 were recorded. The received results contributed for the evaluatation of the optimum nitrogen level, as well as for the determination of a more suitable predecessor of coriander in order to obtain the highest yield of better quality in the region of Southeast Bulgaria

The Antioxidant Role of Xanthurenic Acid in the Aedes aegypti Midgut during Digestion of a Blood Meal

In the midgut of the mosquito Aedes aegypti, a vector of dengue and yellow fever, an intense release of heme and iron takes place during the digestion of a blood meal. Here, we demonstrated via chromatography, light absorption and mass spectrometry that xanthurenic acid (XA), a product of the oxidative metabolism of tryptophan, is produced in the digestive apparatus after the ingestion of a blood meal and reaches milimolar levels after 24 h, the period of maximal digestive activity. XA formation does not occur in the White Eye (WE) strain, which lacks kynurenine hydroxylase and accumulates kynurenic acid. The formation of XA can be diminished by feeding the insect with 3,4-dimethoxy-N-[4-(3-nitrophenyl)thiazol-2-yl] benzenesulfonamide (Ro-61-8048), an inhibitor of XA biosynthesis. Moreover, XA inhibits the phospholipid oxidation induced by heme or iron. A major fraction of this antioxidant activity is due to the capacity of XA to bind both heme and iron, which occurs at a slightly alkaline pH (7.5-8.0), a condition found in the insect midgut. The midgut epithelial cells of the WE mosquito has a marked increase in occurrence of cell death, which is reversed to levels similar to the wild type mosquitoes by feeding the insects with blood supplemented with XA, confirming the protective role of this molecule. Collectively, these results suggest a new role for XA as a heme and iron chelator that provides protection as an antioxidant and may help these animals adapt to a blood feeding habit

Germ band retraction as a landmark in glucose metabolism during Aedes aegypti embryogenesis

<p>Abstract</p> <p>Background</p> <p>The mosquito <it>A. aegypti </it>is vector of dengue and other viruses. New methods of vector control are needed and can be achieved by a better understanding of the life cycle of this insect. Embryogenesis is a part of <it>A. aegypty </it>life cycle that is poorly understood. In insects in general and in mosquitoes in particular energetic metabolism is well studied during oogenesis, when the oocyte exhibits fast growth, accumulating carbohydrates, lipids and proteins that will meet the regulatory and metabolic needs of the developing embryo. On the other hand, events related with energetic metabolism during <it>A. aegypti </it>embryogenesis are unknown.</p> <p>Results</p> <p>Glucose metabolism was investigated throughout <it>Aedes aegypti </it>(Diptera) embryonic development. Both cellular blastoderm formation (CBf, 5 h after egg laying - HAE) and germ band retraction (GBr, 24 HAE) may be considered landmarks regarding glucose 6-phosphate (G6P) destination. We observed high levels of glucose 6-phosphate dehydrogenase (G6PDH) activity at the very beginning of embryogenesis, which nevertheless decreased up to 5 HAE. This activity is correlated with the need for nucleotide precursors generated by the pentose phosphate pathway (PPP), of which G6PDH is the key enzyme. We suggest the synchronism of egg metabolism with carbohydrate distribution based on the decreasing levels of phosphoenolpyruvate carboxykinase (PEPCK) activity and on the elevation observed in protein content up to 24 HAE. Concomitantly, increasing levels of hexokinase (HK) and pyruvate kinase (PK) activity were observed, and PEPCK reached a peak around 48 HAE. Glycogen synthase kinase (GSK3) activity was also monitored and shown to be inversely correlated with glycogen distribution during embryogenesis.</p> <p>Conclusions</p> <p>The results herein support the hypothesis that glucose metabolic fate changes according to developmental embryonic stages. Germ band retraction is a moment that was characterized as a landmark in glucose metabolism during <it>Aedes aegypti </it>embryogenesis. Furthermore, the results also suggest a role for GSK3 in glycogen balance/distribution during morphological modifications.</p

Study of ZnO sol-gel films: Effect of annealing

Thin films of zinc oxide were deposited by spin coating method on different substrates. The obtained samples were thermally treated at temperatures from 400 degrees C up to 850 degrees C. The structural study was performed by XRD and FTIR techniques in order to observe the effect of the annealing temperatures. The sol-gel ZnO films showed polycrystalline hexagonal structure. The optical transmittance reached 91% and it diminished with increasing annealing temperatures. (C) 2010 Elsevier B.V. All rights reserved

Investigation of sol-gel yttrium doped ZnO thin films: structural and optical properties

peer reviewedNanostructured metal oxide films are extensively studied due to their numerous applications such as optoelectronic devices, sensors. In this work, we report the Y–Zn–O nanostructured films prepared by sol-gel technology from sols with different concentration of yttrium precursor, followed by post-annealing treatment. The Y doped ZnO thin films have been deposited on Si and quartz substrates by spin coating method, then treated at températures ranging from 300-800°C. XRD analysis reveals modification of the film structure and phases in the doped ZnO films

Optical characterization of Sol-Gel ZnO:Al thin films

peer reviewedThis paper presents a sol-gel technological process for preparing thin films of ZnO and ZnO:Al. The effect of annealing treatments (500, 600, 700 and 800 oC) on their properties was studied. The structural evolution with the temperature was investigated by using X-Ray diffraction (XRD). Fourier Transform Infrared (FTIR) and UV-VIS spectrophotometry were applied to characterizing the films’ vibrational and optical properties. The ZnO and ZnO:Al films possessed a polycrystalline structure. The films studied are highly transparent in the visible spectral range. The optical band gap values and the haze parameter were also determined

Study of sol-gel Cu-doped Al2O3 thin films: Structural and optical properties

peer reviewedWe present a study of of copper-doped Al2O3 films prepared by sol-gel deposition. The films were spin-coated on Si and quartz substrates and a high-temperature treatment was conducted in the range 500-800 °C in oxygen or nitrogen. The impact was followed of the annealing procedures on the AlxCu1-xO3 films's properties. XRD was used to determine the films' structure; it revealed a mixture of amorphous and crystalline phases. Optical characterization was performed by UV-VIS spectroscopy. The sol-gel films prepared are very transparent. The band gaps of the Al-Cu-O films were estimated from the optical data, with the values ranging from 3.4 to 4.8 eV depending on the Cu content, the annealing and the gas ambients

Structural analysis of Fe Mn O nanoparticles in glass ceramics by small angle scattering

Magnetic nanocrystals containing Fe and Mn were obtained by annealing of silicate glasses with the composition 13.6Na2O 62.9SiO2 8.5MnO 15.0Fe2O3 x mol at 580 C for different periods of time. Here, we present Small Angle Neutron Scattering using Polarized neutrons SANSPOL and Anomalous Small Angle X ray Scattering ASAXS investigation on these glass ceramic samples. Analysis of scattering data from both methods reveals the formation of spherical core shell type of nanoparticles with mean sizes between 10nm and 100 nm. ASAXS investigation shows the particles have higher concentration of iron atoms and the shell like region surrounding the particles is enriched in SiO2. SANSPOL investigation shows the particles are found to be magnetic and are surrounded by a nonmagnetic shell like region