Identification of onosma visianii roots extract and purified shikonin derivatives as potential acaricidal agents against tetranychus urticae

There is an increasing need for the discovery of reliable and eco-friendly pesticides and natural plant-derived products may play a crucial role as source of new active compounds. In this research, a lipophilic extract of Onosma visianii roots extract containing 12% of shikonin derivatives demonstrated significant toxicity and inhibition of oviposition against Tetranychus urticae mites. Extensive chromatographic separation allowed the isolation of 11 naphthoquinone derivatives that were identified by spectral techniques and were tested against Tetranychus urticae. All the isolated compounds presented effects against the considered mite and isobutylshikonin (1) and isovalerylshikonin (2) were the most active, being valuable model compounds for the study of new anti-mite agents

Chemical composition of Cinnamosma madagascariensis (Cannelaceae) essential oil and its larvicidal potential against the filariasis vector Culex quinquefasciatus Say

Madagascar flora is diverse and unique. Cinnamosma madagascariensis is an endemic species widely present in the forests of Madagascar. This plant has important traditional uses ranging from management of dementia, epilepsy, headache to malaria. Fewdata have been reported about the chemical composition of the essential oil, and no studies have been published on its bioactivity againstmosquitoes. Here,we focus on the chemical composition of essential oils extracted from C. madagascariensis stem bark and leaves, and their larvicidal potential against the filariasis vector Culex quinquefasciatus. GC-MS analysis revealed differences between the chemical volatile profiles of leaves and bark oils. In the former, linalool (30.1%), limonene (12.0%), myrcene (8.9%) and α-pinene (8.4%) were the major constituents, while in the latter β-pinene (33.3%), α-pinene (19.3%) and limonene (12.0%) were the most representative compounds. Acute toxicity experiments conducted on larvae of the filariasis vector C. quinquefasciatus led to LC50 of 61.6 μL L−1 and 80.1 μL L−1 for the bark and the leaf essential oils, respectively. Overall, the chance to use compounds from the C. madagascariensis bark and leaf essential oils against filariasis vectors seems promising, since they are effective at moderate doses and could be an advantageous alternative to build newer and safer mosquito control tools. To the best of our knowledge, this is the first report about the chemical composition of C. madagascariensis essential oils

Insecticidal Activity of Four Essential Oils Extracted from Chilean Patagonian Plants as Potential Organic Pesticide

Patagonia is a geographical area characterized by a wide plant biodiversity. Several native plant species are traditionally used in medicine by the local population and demonstrated to be sources of biologically active compounds. Due to the massive need for green and sustainable pesticides, this study was conducted to evaluate the insecticidal activity of essential oils (EOs) from understudied plants growing in this propitious area. Ciprés (Pilgerodendron uviferum), tepa (Laureliopsis philippiana), canelo (Drimys winteri), and paramela (Adesmia boronioides) EOs were extracted through steam distillation, and their compositions were analyzed through GC–MS analysis. EO contact toxicity against Musca domestica L., Spodoptera littoralis (Boisd.), and Culex quinquefasciatus Say was then evaluated. As a general trend, EOs performed better on housefly males over females. Ciprés EO showed the highest insecticidal efficacy. The LD50(90) values were 68.6 (183.7) and 11.3 (75.1) µg adult−1 on housefly females and males, respectively. All EOs were effective against S. littoralis larvae; LD50 values were 33.2–66.7 µg larva−1, and tepa EO was the most effective in terms of LD90 (i.e., <100 µg larva−1). Canelo, tepa, and paramela EOs were highly effective on C. quinquefasciatus larvae, with LC50 values < 100 µL L−1. Again, tepa EO achieved LD90 < 100 µL L−1. This EO was characterized by safrole (43.1%), linalool (27.9%), and methyl eugenol (6.9%) as major constituents. Overall, Patagonian native plant EOs can represent a valid resource for local stakeholders, to develop effective insecticides for pest and vector management, pending a proper focus on their formulation and nontarget effects

Liquidation of Corporation

Import 22/07/2015Diplomová práce se zabývá procesem likvidace obchodních společností v České republice. Cílem této práce je popsat postup likvidace obchodních společností a upozornit na některé problémy, které proces likvidace s sebou přináší, poukázat na řešení základních organizačních a ekonomických otázek související s likvidací a propojit právní a daňový pohled na likvidaci. Práce je rozdělena do čtyř kapitol. V první kapitole jsou definovány jednotlivé právní formy obchodních společností a možné způsoby jejich zrušení. Druhá kapitola se zabývá popisem likvidačního procesu, kdy jsou popsány jednotlivé kroky likvidátora v průběhu likvidace. Třetí kapitola je věnována osobě likvidátora, podmínky nutné k výkonu likvidátora, povolání likvidátora do funkce. Čtvrtá kapitola je věnována praktickým problémům spojenými s procesem likvidace.Thesis deals with the process of liquidation of corporations in the Czech Republic. The aim of this thesis is to describe the procedure of liquidation and to point out some possible problems that could occur during liquidation. The legal and tax point view of the topic will also be included. Thesis is divided into 4 main chapters. Different legal forms of the corporations and the ways of dissolution of companies are defined in the first chapter. The second chapter pursues the process of liquidation. One part of this chapter is devoted to activities of the liquidator. The person of the liquidator, including his competences and required skills, is described in the third chapter. The last chapter is focused on practical problems concerning the process of liquidation.119 - Katedra právavelmi dobř

Bumble bee parasite strains vary in resistance to phytochemicals

Nectar and pollen contain diverse phytochemicals that can reduce disease in pollinators. However, prior studies showed variable effects of nectar chemicals on infection, which could reflect variable phytochemical resistance among parasite strains. Inter-strain variation in resistance could influence evolutionary interactions between plants, pollinators, and pollinator disease, but testing direct effects of phytochemicals on parasites requires elimination of variation between bees. Using cell cultures of the bumble bee parasite Crithidia bombi, we determined (1) growth-inhibiting effects of nine floral phytochemicals and (2) variation in phytochemical resistance among four parasite strains. C. bombi growth was unaffected by naturally occurring concentrations of the known antitrypanosomal phenolics gallic acid, caffeic acid, and chlorogenic acid. However, C. bombi growth was inhibited by anabasine, eugenol, and thymol. Strains varied >3-fold in phytochemical resistance, suggesting that selection for phytochemical resistance could drive parasite evolution. Inhibitory concentrations of thymol (4.53-22.2 ppm) were similar to concentrations in Thymus vulgaris nectar (mean 5.2 ppm). Exposure of C. bombi to naturally occurring levels of phytochemicals—either within bees or during parasite transmission via flowers—could influence infection in nature. Flowers that produce antiparasitic phytochemical, including thymol, could potentially reduce infection in Bombus populations, thereby counteracting a possible contributor to pollinator decline

Semiochemical-based alternatives to synthetic toxicant insecticides for pollen beetle management

There is an urgent need to develop sustainable pest management systems to protect arable crops in order to replace the current over-reliance on synthetic insecticides. Semiochemicals are insect- or plant-derived chemicals that are used by organisms as information signals. Integrated pest management tools are currently in development that utilise semiochemicals to manipulate the behaviour of pest insects and their natural enemies to provide effective control of pests within the crop. These innovative tools usually require fewer inputs and can involve multiple elements therefore reducing the likelihood of resistance developing compared with use of synthetic toxicants. We review here the life cycle of the pollen beetle Brassicogethes aeneus (previously known as Meligethes aeneus) which is a pest insect of oilseed rape (Brassica napus) and describe the current knowledge of any behaviour mediated by semiochemicals in this species. We discuss the behavioural processes where semiochemical-based control approaches may be appropriate and consider how these approaches could be integrated into an integrated pest management strategy for this important arable crop