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Bark beetles on logging residues of European larch: Effects of shading and diameter of logging residues on infestation density
Get PDF1. Ips cembrae, an important pest of European larch (Larix decidua), has caused local outbreaks in the last two decades and is becoming increasingly important as the proportion of European larch in forests increases. 2. In 2021-2023, larch logs and piles of branches were placed into shaded forest and sunlit areas every month to study bark beetle species on logging residues. After adult emergence, the logs and branches were debarked, and the infestation density of bark beetles was analysed. The results indicate that shading, log diameter and top/bottom parts of log had a significant effect on infestation density of I. cembrae on logs. The infestation density of I. cembrae was higher on logs felled between December and June than on logs felled between July and November. 3. Shading of branches was the most significant variable affecting the bark beetle species composition on branches. All four of the bark beetle species recorded were affected by diameter of the branches. Ips cembrae primarily infested sunlit branches while Cryphalus intermedius preferred shaded branches. In contrast, the infestation densities of Pityogenes chalcographus and Pityophthorus pityographus seemed to be affected primarily by moisture content of the branches.O
Germination responses with different treatments, seed vigour and seedling growth of Pterolobium stellatum (Forssk.) provenances stored from 19 to 30 years
Get PDFKnowledge of the genetic variability of different species for conservation purposes and quality seedling production after longer storage time is important. The aim of the research paper was to examine the effect of longer seed storage periods (19-30 year) on seed viability, seed vigour and initial growth of seedlings from five provenances of Pterolobium stellatum (Forssk). Seeds collected from Dabena, Gambo, Agaro, Bishofitu, and Merti localities and stored for 19, 19, 21, 25, and 30 years, respectively used for the study. Different seed dormancy-breaking treatments such as; soaking in cold water for 48 h (CW-48); soaking in hot water for 10 min (HW-10); 20 min (HW-20) and mechanical scarification; i.e., nicking (NK) used for the germination of the seeds. A randomized complete block design was used for the experiment and the study undertaken in a greenhouse. For each treatment, four replications and for each replication, 50 seeds were used. One-way analysis of variance was used for germination index, early seedling growth and seed vigour index data. The results showed that for all the provenance seeds stored for different periods, NK treatment resulted relatively in a higher mean germination percentage and germination indices as compared to the other pre-treatments. The seed vigour index result showed significant differences among the different provenances (P < 0.001). Similarly, there were significant differences among the early growth of seedlings germinated from different provenance seeds (P < 0.001). The seeds collected from Merti provenance and stored for 30 years and Dabena provenance, stored for 19 years, have relatively resulted in higher mean germination index, seed vigour and seedling growth relative to the other studied provenance seeds. We observed that provenance had a more significant influence on germination, seed vigour and seedling growth than the seed storage period for the P. stellatum. Finally it is recommended that despite there is inter population variation, the seeds of P. stellatum can be stored for a longer time and application of nicking as a dormancy breaking treatment could enhance seed germination of the species.OA-hybri
Synergistic effect of selected carboxylic acids and phenolic compounds detected by the FRAP method
Get PDFAntioxidants in nutrition are a widely discussed topic. In this study, a synergistic effect was observed for 13 selected substances - antioxidants and potential synergists, whereby two substances were mixed in the same concentration ratio of 1:1. The antioxidant capacity (AC) of the mixtures was determined using the FRAP method. The AC measured was compared with a theoretical AC value (as only additive effect) to calculate the synergistic or antagonistic effect. Out of 78 possible combinations, a synergistic effect (SE) was detected in 72. For the 10 combinations, the SE was more than twice that of the pure substances. The largest synergistic effect was exhibited by vanillin and 4-hydroxybenzoic acid with increases even above 200% compared to the pure substances. Some of the phenolic substances that were subject to measurement can be used for the fortification of fruit juices.O
Effects of digital skills and other individual factors on retirement decision-making and their gender differences
Get PDFIncreasing the pension age as a dominant solution to population ageing does not bring desirable outcomes, if not accompanied by other essential measures in lifelong learning and fighting age discrimination. Moreover, rapid digitalisation and automation in the labour market bring additional uncertainties for the growing group of older workers. The analysis is based on the SHARE data from Waves 5, 6, and 7 and examines predictors of retirement intentions by two different estimation methods. While digital skills are positively associated with a willingness to stay in the labour market in the random-effect modelling, fixed-effects regression shows no correlation between digital skills and retirement intentions. This difference means that digital skills do not correlate with retirement intentions once we control for time-invariant individual characteristics. Thus, increasing ICT literacy among older workers can have a very limited potential for extending working lives. In contrast to this result, starting to be self-employed, health improvement, having an additional grandchild, and losing a partner increase the willingness to work longer. The study identifies the factors shaping retirement intentions, which should be reflected in any effective social policy.OA-hybri
Incipient decay in beech (Fagus sylvatica L.) and linden (Tilia cordata Mill.): An interspecific static and dynamic material analysis
Get PDFWith increasing awareness of the ecological value of trees in urban areas, there is a growing need to preserve mature specimens often colonised by wood-decay fungi. Nonetheless, cases of stem collapse or uprooting of such trees under adverse weather conditions remain a significant issue requiring further investigation. Depending on the decay type and the wood structure of the host tree, different combinations of wood-decaying fungi and host species can have varying impacts on the mechanical and vibroacoustic properties of green wood. This study compares the physical and mechanical properties of green European beech (Fagus sylvatica L.) and small-leaved linden (Tilia cordata Mill.) artificially exposed to Fomes fomentarius (L.) Fr. and Kretzschmaria deusta (Hoff.) P.M.D. Martin after different exposure periods. Mass loss () caused by both fungi differed according to the wood species. A statistically significant difference between the two fungal species was observed in beech wood, but not in linden. Significant differences in the modulus of rupture () and dynamic bending modulus of elasticity () were observed among the fungus-wood combinations, also depending on the exposure time. The relationships between and varied according to the fungal species, where at the same values, K. deusta caused a higher loss in both wood species. Strong relationships between and were demonstrated for all fungus-wood combinations, without significant differences related to the decay type. The is a reliable parameter for predicting loss even at incipient degradation stages, irrespective of the type of decay. The presented results can lead to better prediction of the impact of fungal colonization on standing trees and improve non-destructive methods used for tree stability assessment.OA-hybri
Diversity and impact of single-stranded RNA viruses in Czech Heterobasidion populations
Get PDFHeterobasidion annosum sensu lato comprises some of the most devastating pathogens of conifers. Exploring virocontrol as a potential strategy to mitigate economic losses caused by these fungi holds promise for the future. In this study, we conducted a comprehensive screening for viruses in 98 H. annosum s.l. specimens from different regions of Czechia aiming to identify viruses inducing hypovirulence. Initial examination for dsRNA presence was followed by RNA-seq analyses using pooled RNA libraries constructed from H. annosum and Heterobasidion parviporum, with diverse bioinformatic pipelines employed for virus discovery. Our study uncovered 25 distinct ssRNA viruses, including two ourmia-like viruses, one mitovirus, one fusarivirus, one tobamo-like virus, one cogu-like virus, one bisegmented narna-like virus and one segment of another narna-like virus, and 17 ambi-like viruses, for which hairpin and hammerhead ribozymes were detected. Coinfections of up to 10 viruses were observed in six Heterobasidion isolates, whereas another six harbored a single virus. Seventy-three percent of the isolates analyzed by RNA-seq were virus-free. These findings show that the virome of Heterobasidion populations in Czechia is highly diverse and differs from that in the boreal region. We further investigated the host effects of certain identified viruses through comparisons of the mycelial growth rate and proteomic analyses and found that certain tested viruses caused growth reductions of up to 22% and significant alterations in the host proteome profile. Their intraspecific transmission rates ranged from 0% to 33%. Further studies are needed to fully understand the biocontrol potential of these viruses in planta.O
Competitiveness of Individuals in the Labour Market During the Pandemic
Get PDFThe global COVID-19 pandemic has changed the behaviour of individuals and companies. This study aims to determine changes in the labour market behaviour of economically active individuals in the context of the pandemic and to identify competitive segments in this period. For this purpose, a representative survey (n = 3079) conducted in the Czech Republic was used. The paper's contribution is a perspective of individuals' behaviour and their perception of the situation. Based on subjective perceptions, respondents provided an assessment of their living situation before and during the pandemic, expressing their opinion on the importance of selected aspects of quality of life, such as their health, active social contacts, creation of financial savings, ability to pay bills, leisure time and coping with stressful situations. The results of a Wilcoxon test showed that individuals re-evaluated each aspect of life and that the pandemic changed the importance for all of them (except leisure time). This change is also reflected in their psyche, attitude towards work organisation, digitalisation and other factors; these were applied in a cluster analysis, which resulted in the identification of three segments in the group of employees in the labour market (competitive individuals, surviving individuals and those reluctant to respond to change). For the group of entrepreneurs, two segments emerged (flexible and loss-creating), while for the unemployed group, the typical segment can be described as dissatisfied and Covid victims. The names of these segments indicate their behaviour and provide possibilities for future use.O
Phytophthora, Nothophytophthora and Halophytophthora diversity in rivers, streams and riparian alder ecosystems of Central Europe
Get PDFWaterways are ideal pathways for Phytophthora dispersal and potential introduction to terrestrial ecosystems. While many Phytophthora species from phylogenetic clades 6, 9 and 10 are predominant oomycetes in watercourses due to their adaptation to a lifestyle as saprotrophs and opportunistic pathogens of riparian plants, species from clades 2, 7 and 8 are predominantly soil- or airborne using aquatic habitats as temporal niches for spreading and invading terrestrial sites along the watercourses. In contrast to forest ecosystems, knowledge of Phytophthora diversity in watercourses in Central Europe is limited. Between 2014 and 2019 extensive surveys of streams and rivers were undertaken across Austria, in South Moravia, Czech Republic and Žilina province, Slovakia to unveil the diversity and distribution of Phytophthora and related oomycetes. In addition, in Austria riparian forests of black alder (Alnus glutinosa) and grey alder (A. incana) in lowlands and in the Alps were examined. A variety of Phytophthora species from clades 2, 6, 7, 8, 9 and 10 were isolated, with clade 6 species showing the widest distribution and abundance. Furthermore, interspecific clade 6 hybrids and other oomycetes such as Halophytophthora fluviatilis and undescribed Nothophytophthora spp. were also obtained. In riparian alders, symptoms of Phytophthora infections were associated with species from the P. x alni complex and P. plurivora. Phytophthora plurivora was most common in alder stands whereas P. uniformis was the oomycete species occurring at the highest altitude in alpine riparian areas.OA-hybri
Patterns of Ips cembrae (Herr) infestation on trap and standing trees of European larch (Larix decidua Mill.)
Get PDFThe large larch beetle, Ips cembrae, is a significant pest causing the death of larch. In 2020, the attack density of I. cembrae on larch trap trees and standing trees was evaluated using sample sections placed along the trunk. As a defensive measure against I. cembrae, trap trees were highly effective in both spring and summer. The attack density increased with increasing trap tree surface area/volume. Galleries were established evenly throughout the entire trunk including the thin upper portion. When the number of trap trees was low and their capacity full, a continual aggregation of adults occurred due to pheromone communication, leading to attacks on healthy standing trees in the immediate vicinity. It was found that I. cembrae attacked standing trees from the trunk base, with a continual colonization of the stem up to 70% of the tree height in a time-differentiated progression of development stages. The attack density of I. cembrae on standing trees was up to 40% lower than on the trap trees.OA-hybri
Female melon fruit flies, Zeugodacus cucurbitae, are attracted to a synthetic chemical blend based on male epicuticular components
Get PDFThe melon fly, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae), is considered to be the most destructive pest of melons and other related cucurbit crops worldwide. Despite the potential of behaviour-based control strategies, little is known about the mechanisms involved in female mate choice. Herein, we investigated the production and chemoreception of cuticular hydrocarbons in both sexes of Z. cucurbitae, and the behavioural responses they induce. We studied the epicuticular composition of virgin males and females, using two-dimensional gas chromatography coupled with mass spectrometric detection. Data were interpreted using multivariate factorial analysis. The differentiation of chemical profiles was consistently observed over time. In young individuals, the chemical profiles did not differ between sexes, while sex-specific differences were noted in mature flies. The fly olfactory sensitivity to these compounds was explored using gas chromatography combined with chopped triple electroantennography and electropalpography detectors. This extensive exploration of the pest olfactory sensitivity highlighted three compounds produced by the male. When blended, they induced a robust positive response in unmated naive females in a six-choice olfactometer. The responsiveness of other Tephritidae species (a polyphagous species Bactrocera dorsalis (Hendel) and the cucurbit specialist Dacus demmerezi (Bezzi)) to whole body extracts of Z. cucurbitae was also investigated. Our findings showed that Z. cucurbitae uses species-specific olfactory receptors to detect male produced compounds. In addition, the palps were sensitive to a female-specific component, 1,7-dioxaspiro[5.5]undecane, which the males produce in minute quantities. Overall, this study provides a starting point for a pheromone-based tephritid lure that targets unmated females. The potential implications for pest management are discussed.OA-hybri