Occurrence and impact of the parasitic mite Linobia coccinellae on its host beetle Chrysomela populi: implications for its potential as a biological control agent

Due to social demands with regard to sustainability and ecological considerations, an aim of current research in short-rotation coppices (SRC) is to find effective candidates for biological control of pest species. The great red poplar leaf beetle, Chrysomela populi L. (Coleoptera: Chrysomelidae), is one of the most harmful pests in the SRC. The endoparasitic mite Linobia coccinellae (Scopoli) (Acari: Astigmata, Hemisarcoptidae) lives under the elytra of C. populi and feeds on the beetles' hemolymph. The population dynamics of the mites and their impact on the fecundity and longevity of female beetles were examined in two experiments. To study the occurrence of the mites, beetles were collected from two poplar SRC sites in Germany on three dates. Infestation rates of collected male and female C. populi individuals increased over the course of the year and reached 78–97% in the last survey. Females were parasitized more often than males at any time. For the second part of the study, beetles were reared under laboratory conditions to study the development of the mites and their impact on the hosts. For this purpose, half of the females were actively seeded with five adult females of L. coccinellae and the other half was used as a control. There was no significant impact on longevity or reproductive traits of the beetles. Despite the high rates of infestation, it appears that the mites do not have a serious effect on female beetles. Thus L. coccinellae, by itself, is not an effective biological control agent against C. populi. However, it remains to be investigated whether the mites increase the beetles' susceptibility to other biotic and abiotic factors, and so may contribute to an integrated pest management regime with multiple antagonists.     

Biochemical and Physiological Responses of <i>Arabidopsis thaliana</i> Leaves to Moderate Mechanical Stimulation

Mechanical stimulation of plants can be caused by various abiotic and biotic environmental factors. Apart from the negative consequences, it can also cause positive changes, such as acclimatization of plants to stress conditions. Therefore, it is necessary to study the physiological and biochemical mechanisms underlying the response of plants to mechanical stimulation. Our aim was to evaluate the response of model plant Arabidopsis thaliana to a moderate force of 5 N (newton) for 20 s, which could be compared with the pressure caused by animal movement and weather conditions such as heavy rain. Mechanically stimulated leaves were sampled 1 h after exposure and after a recovery period of 20 h. To study a possible systemic response, unstimulated leaves of treated plants were collected 20 h after exposure alongside the stimulated leaves from the same plants. The effect of stimulation was assessed by measuring oxidative stress parameters, antioxidant enzymes activity, total phenolics, and photosynthetic performance. Stimulated leaves showed increased lipid peroxidation 1 h after treatment and increased superoxide dismutase activity and phenolic oxidation rate after a 20-h recovery period. Considering photosynthetic performance after the 20-h recovery period, the effective quantum yield of the photosystem II was lower in the stimulated leaves, whereas photochemical quenching was lower in the unstimulated leaves of the treated plants. Nonphotochemical quenching was lower in the stimulated leaves 1 h after treatment. Our study suggested that plants sensed moderate force, but it did not induce pronounced change in metabolism or photosynthetic performance. Principal component analysis distinguished three groups–leaves of untreated plants, leaves analysed 1 h after stimulation, while stimulated and unstimulated leaves of treated plants analysed 20 h after treatment formed together the third group. Observed grouping of stimulated and unstimulated leaves of treated plants could indicate signal transduction from the stimulated to distant leaves, that is, a systemic response to a local application of mechanical stimuli.     

QoS and Contention-Aware Multi-Resource Reservation

To provide Quality of Service (QoS) guarantee in distributed services, it is necessary to reserve multiple computing and communication resources for each service session. Meanwhile, techniques have been available for the reservation and enforcement of various types of resources. Therefore, there is a need to create an integrated framework for coordinated multi-resource reservation. One challenge in creating such a framework is the complex relation between the end-to-end application-level QoS and the corresponding end-to-end resource requirement. Furthermore, the goals of (1) providing the best end-to-end QoS for each distributed service session and (2) increasing the overall reservation success rate of all service sessions are in conflict with each other. In this paper, we present a QoS and contention-aware framework of end-to-end multi-resource reservation for distributed services. The framework assumes a reservation-enabled environment, where each type of resource can be reserved. The framework consists of (1) a component-based QoS-Resource Model, (2) a runtime system architecture for coordinated reservation, and (3) a runtime algorithm for the computation of end-to-end multi-resource reservation plans. The algorithm provides a solution to alleviating the conflict between the QoS of an individual service session and the success rate of all service sessions. More specifically, for each service session, the algorithm computes an end-to-end reservation plan, such that it guarantees the highest possible end-to-end QoS level under the current end-to-end resource availability, and requires the lowest percentage of bottleneck resource(s) among all feasible reservation plans. Our simulation results show excellent performance of this algorithm.     

Cytotoxicity and Antioxidative Effects of Herbal and Fruit Extracts In Vitro

Many studies have been carried out on bioactivities of individual herbs/fruits using in cosmetics or as a diet products, however, no collective study on their comparative antioxidant activities against oxidative damage or on cytotoxicity effect has been reported. The aim of this work was study the cytotoxicity and antioxidative activity of eight extracts with hypothetical antioxidative influence in vitro. To further elucidate of a possible role of herbals/fruits extracts on cell protection was used on the healthy and UV-A damaged mouse fibroblast cells. The cell viability was detect using MTT assay. Kinetic production of reactive oxygen species, identification of cell death, cell cycle and gene expression C-FOS were measured. Intracellular and mitochondrial transmembrane potential was evaluate with JC-1 fluorescence probe. Comet assay was employed to detect the UV-A induced DNA damage. The results indicated that using the extracts decreased ROS production. It can lead to greatly enhance and promote the viability of cells. As the most effective antioxidant in quenching of the ROS, in cell viability and DNA presentation was determined Prunella Vulgaris. However, one of them (Wheat Germ Oil) caused increased production of ROS and low cell viability.