Search

Non-native pests, climate change, and their interactions are likely to alter relationships between trees and tree-associated organisms with consequences for forest health. To understand and predict such changes, factors structuring tree-associated communities need to be determined. Here, we analysed the data consisting of records of insects and fungi collected from dormant twigs from 155 tree species at 51 botanical gardens or arboreta in 32 countries. Generalized dissimilarity models revealed similar relative importance of studied climatic, host-related and geographic factors on differences in tree-associated communities. Mean annual temperature, phylogenetic distance between hosts and geographic distance between locations were the major drivers of dissimilarities. The increasing importance of high temperatures on differences in studied communities indicate that climate change could affect tree-associated organisms directly and indirectly through host range shifts. Insect and fungal communities were more similar between closely related vs. distant hosts suggesting that host range shifts may facilitate the emergence of new pests. Moreover, dissimilarities among tree-associated communities increased with geographic distance indicating that human-mediated transport may serve as a pathway of the introductions of new pests. The results of this study highlight the need to limit the establishment of tree pests and increase the resilience of forest ecosystems to changes in climate. [ABSTRACT FROM AUTHOR]

Hymenoscyphus fraxineus causes ash dieback in Europe and threatens the future existence of Fraxinus excelsior in large parts of its natural distribution range. In this study, we report the first documented distribution of the pathogen on the most common ash species F. excelsior in Slovakia, identified molecularly using species-specific primers and based on sequencing of the ITS region of rDNA. Analysis of the mating type genes of H. fraxineus isolates revealed the presence of both mating types in Slovakia. Hymenoscyphus fraxineus-positive trees were recorded in 70 localities with different types of management in different parts of the country, mainly in forest stands. The results indicate the widespread distribution of H. fraxineus across the entire country, wherever the host is present. [ABSTRACT FROM AUTHOR]

The western corn rootworm (WCR), Diabrotica virgifera virgifera, is an invasive alien species and an important pest of maize in Europe. The insecticide potential of Greek oregano, Origanumvulgare subsp. hirtum, essential oil (EO) and the entomopathogenic fungus Metarhizium pemphigi were evaluated against WCR adults in laboratory conditions as alternative control agents. Pure undissolved Greek oregano EO applied at a volume of 3, 5 and 10 µl caused 97–100% mean corrected mortality of the test individuals with a rapid lethal effect. Treatment of WCR with four concentrations of EO (0.01, 0.1, 1 and 10 µl/ml) showed a strong concentration–time effect. Mortality rate increased with increasing concentration and exposure time. The median lethal concentration LC50 was 0.03 µl/ml. The time needed for Greek oregano EO to cause LT50 of D. v. virgifera ranged from 17.95 days for the lowest concentration (0.01 µl/ml) to 90 min for the highest concentration (10 µl/ml). Metarhizium pemphigi, which was tested in five conidia concentrations (2 × 103–2 × 107 conidia/ml), showed relatively lower effectiveness against D. v. virgifera adults. At the end of the bioassay (ten days post-treatment), the mean corrected mortality of the test specimens varied from 14 to 73%. LC50 was 3.3 × 106 conidia/ml. The results showed that Greek oregano EO had a bioinsecticidal effect against WCR adults at low concentrations and they are a basis for further investigations on the EO as an environmentally friendly alternative to chemical insecticides. [ABSTRACT FROM AUTHOR]

Adults of the large pine weevil (Hylobius abietis) cause serious damage to coniferous seedlings and are among the most important forest pests in Europe. Seedling protection by chemicals is gradually being restricted or banned for environmental reasons, and non-chemical alternatives are therefore needed. In this 3-year study, we compared the following five treatments for protecting Norway spruce seedlings against H. abietis in the Central European mountains where the weevil is especially abundant: alpha-cypermethrin sprays (the only chemical treatment); coating with sprayed glue (Vermifix); wax coating with C and F types (Norsk Wax); and physical protection with collars. The same block design was set up at a clear-cut site and at a nursery site to compare seedling mortality and wax quality under "wild conditions" with pests and under "ideal conditions" without pests. Repeated application of alpha-cypermethrin was the most effective and least expensive method to protect seedlings against H. abietis. Among the four non-chemical methods, repeated application of glue was the most effective. Because collars were moderately effective but not cost-effective, we do not recommend the use of collars. Wax was inexpensive and environmentally safe but protected seedlings for only 1 year; the newer F type of wax performed better than the C type of wax, and perhaps the F type can be improved. In general we found that seedlings at sites with high numbers of H. abietis require protection for at least 3 years. We conclude by providing an overview of all methods currently available for managing H. abietis in forests. [ABSTRACT FROM AUTHOR]

International trade in plants and climate change are two of the main factors causing damaging tree pests (i.e. fungi and insects) to spread into new areas. To mitigate these risks, a large-scale assessment of tree-associated fungi and insects is needed. We present records of endophytic fungi and insects in twigs of 17 angiosperm and gymnosperm genera, from 51 locations in 32 countries worldwide. Endophytic fungi were characterized by high-throughput sequencing of 352 samples from 145 tree species in 28 countries. Insects were reared from 227 samples of 109 tree species in 18 countries and sorted into taxonomic orders and feeding guilds. Herbivorous insects were grouped into morphospecies and were identified using molecular and morphological approaches. This dataset reveals the diversity of tree-associated taxa, as it contains 12,721 fungal Amplicon Sequence Variants and 208 herbivorous insect morphospecies, sampled across broad geographic and climatic gradients and for many tree species. This dataset will facilitate applied and fundamental studies on the distribution of fungal endophytes and insects in trees. Measurement(s) metagenomics analysis • Cytochrome C Oxidase Subunit 1 Technology Type(s) amplicon sequencing • Dideoxy Chain Termination DNA Sequencing Factor Type(s) tree species • geographic location • mean annual temperature • mean annual precipitation Sample Characteristic - Organism Fungi • Insecta Sample Characteristic - Environment dormant tree twigs Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.16764229 [ABSTRACT FROM AUTHOR]

For non-native tree species with an origin outside of Europe a detailed compilation of enemy species including the severity of their attack is lacking up to now. We collected information on native and non-native species attacking non-native trees, i.e. type, extent and time of first observation of damage for 23 important non-native trees in 27 European countries. Our database includes about 2300 synthesised attack records (synthesised per biotic threat, tree and country) from over 800 species. Insects (49%) and fungi (45%) are the main observed biotic threats, but also arachnids, bacteria including phytoplasmas, mammals, nematodes, plants and viruses have been recorded. This information will be valuable to identify patterns and drivers of attacks, and trees with a lower current health risk to be considered for planting. In addition, our database will provide a baseline to which future impacts on non-native tree species could be compared with and thus will allow to analyse temporal trends of impacts. Measurement(s) area of attack of enemy species on non-native tree • intensity of attack of enemy species on non-native tree Technology Type(s) species identification • visual observation method Factor Type(s) plant health • country • species Sample Characteristic - Organism tree Sample Characteristic - Environment forested area Sample Characteristic - Location Europe Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.14345921 [ABSTRACT FROM AUTHOR]

Symptoms of dry clove rot of Allium sativum produced in Slovakia were noticed during storage in 2019. In 2020, garlic bulbs of eight cultivars were analysed and fungal isolates were obtained. Morphological and molecular identification confirmed the isolation of Fusarium proliferatum from all cultivars. The mean proportion of symptomatic cloves in evaluated samples reached 78.68%, and the mean area of clove surface damaged by the disease ranged from 5.97% to 14.83% 5 weeks after the harvest. The pathogenicity of the selected F. proliferatum isolate was verified by inoculation of garlic cloves in laboratory bioassays. This is the first report of F. proliferatum causing dry rot of garlic bulbs in Slovakia. [ABSTRACT FROM AUTHOR]

Key message: Endophytic fungus, usually treated as an entomopathogenic agent, can provide drought stress tolerance to red oak seedlings. Its effect is realized through root growth stimulation. Endophytic fungi are known to be active in the plant environmental stress alleviation. In this work, we proved the ability of endophytic Beauveria bassiana, which is almost exclusively treated as an entomopathogenic fungus, in mitigating drought stress in dehydrated red oak (Quercus rubra L.) seedlings. Despite small differences between experiments, in general, leaf relative water content and stomatal conductance were less reduced (ca. 50% and 15%, respectively), free proline did not accumulate over the control level, carbon isotope 13C discrimination/water use efficiency was not affected and root growth was stimulated at a similar plant transpiration area in the endophyte-colonised individuals. Regression analysis revealed that the root growth stimulation provided by the fungus under drought had the most important effect on their water status. [ABSTRACT FROM AUTHOR]

The Eurasian spruce bark beetle, Ips typographus (IT), is considered the most destructive insect pest of spruce forests in the Palaearctic region. Its control is based on a range of phytosanitary measures, insecticide treatments targeting the tree trunks, and pheromone trappings. Essential oils (EOs) from aromatic plants have been recognized as ecological alternatives to synthetic pesticides. In this study, EOs from plants in the Lamiaceae family (Origanum vulgare, Thymus vulgaris, Hyssopus officinalis and Mentha × piperita) and the Apiaceae family (Pimpinella anisum and Foeniculum vulgare) were studied for insecticidal and repellent effects against IT. EOs chemical composition was analyzed with gas chromatography mass spectrometry. IT adults were exposed to different concentrations of EOs, and their effects were recorded 2-96 h post-treatment. Significant differences in biological activity were observed, and the greatest insecticidal effect was detected for O. vulgare, T. vulgaris, and P. anisum; but O. vulgare EO was significantly more toxic at all doses or exposure times. Repellency index (RI) varied among the EOs and depended on dose and exposure time. At doses of 0.077‒0.219 µl/cm2, the RI increased until 4‒6 h post-treatment; after that period, it decreased. Pimpinella anisum, O. vulgare, and T. vulgaris EOs showed significantly higher repellent effects compared to F. vulgare and H. officinalis EOs. Mentha × piperita EOs exhibited neither repellent nor insecticidal activity against IT. To our knowledge, this is the first time that EOs biological activity against IT was studied. [ABSTRACT FROM AUTHOR]

In Slovakia, a diversity of entomopathogenic fungi (Ascomycota, Hypocreales) associated with outbreaks of Ips typographus was studied in 81 localities and as many as 113 in vitro cultures of five entomopathogenic species were isolated from infected individuals: Beauveria bassiana (87 isolates), B. pseudobassiana (14 isolates), B. caledonica (6 isolates), Lecanicillium lecanii (4 isolates) and Isaria farinosa (2 isolates). B. pseudobassiana is recorded in natural populations of I. typographus for the first time. Biological properties of selected Beauveria isolates, including colony growth, biomass production, conidia yield and pathogenicity to I. typographus adults, were studied in a series of laboratory bioassays and much intra- and interspecific variability was detected. B. bassiana isolates produced biomass or conidia at significantly higher rate than B. pseudobassiana and B. caledonica isolates. Two B. bassiana isolates were selected as the most virulent to bark beetle adults, demonstrating a mean LC50 ranging from 0.72 to 2.05 × 106 conidia ml−1, and were qualified as promising candidates for biocontrol of I. typographus. Their virulence was significantly higher than that of the mycoinsecticides Boverol®, which was used as a reference strain in the virulence bioassays. [ABSTRACT FROM AUTHOR]

The cypress aphid ( Cinara cupressi) is listed among the hundred most important invasive pests in the world. In Chile, it was first detected in 2003 and currently is present throughout the country. In the course of a survey of their natural enemies in Chile, three strains of entomopathogenic fungi were isolated. The isolates were identified and tested against the aphid in laboratory experiments. Two further entomopathogenic fungi (ARSEF 5126 and 5128), formulated in the mycoinsecticides Vertalec and Mycotal, were used as reference strains. The three Chilean isolates were identified genomically as Lecanicillium attenuatum and were pathogenic to third-instar nymphs. The isolate ARSEF 13279 yielded the lowest overall lethal concentration (LC), 3 × 10 conidia ml at four days post-inoculation, and the shortest lethal time (LT), 3.7 days after inoculation with 10 conidia ml. The results indicate that the isolates have considerable potential as microbial control agents of the invasive cypress aphid. [ABSTRACT FROM AUTHOR]

Leptoglossus occidentalis, a species native to North America, has been expanding through European conifer forests. The fast spread across the European continent demonstrates its great invasive potential and poses a threat to conifer seed orchards. To better understand its potential distribution and population growth in infested regions, the temperature-dependent development in laboratory as well as life history, phenology, and winter survival were investigated in southern Slovakia during 2009-2011. The lower temperature thresholds to complete embryonic and postembryonic development estimated with the linear model were 13.38 and 14.37 °C, respectively. The number of degree-days required for completion of development from egg to adult estimated by the linear model was 533 °C. Overwintered adults or late nymphal instars became active in mid-March, oviposition was not observed before mid-April, and nymphs passing through five stages reached adulthood after mid-July. Individual females laid on average 31 eggs (max 78). The second generation started in August but did not complete its development till winter, although part of the 5th instar nymphs did survive until spring. Using temperature data of 41 localities across Europe and cumulative degree-days for complete life cycle, a prediction of the potential number of generations per year was made. In conditions of southern Slovakia L. occidentalis was univoltine, but up to four generations per year were estimated depending on the locality in Europe. [ABSTRACT FROM AUTHOR]

In the laboratory, a commercial neem-based insecticide—Nimbecidine®—was evaluated as a potential pest management tool for the terrestrial snail, Monacha obstructa (Pfeiffer, 1842) (Hygromiidae). Effects of different concentrations of the botanical insecticide on food consumption and egg hatchability of the terrestrial snail were studied. Generally, food consumption of immature and adult snails decreased as the concentrations of Nimbecidine® increased. At the highest concentration (10 ml/l), the snails avoided contacting with food completely. The food intake of immature individuals was significantly ( p < 0.05) more affected by the Nimbecidine® treatment (at 1.25 ml/l) than that of adults. LC50 of Nimbecidine® for the treated eggs was 2.18 ml/l, and eggs failed to hatch at concentration of 10 ml/l. Nimbecidine® showed sufficient biological activity against the food consumption and eggs viability of M. obstructa, thus the preparation has a potential to protect field crops from this pest snails. [ABSTRACT FROM AUTHOR]