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The oak lace bug Corythucha arcuata (Hemiptera: Tingidae), native to North America, has already colonized millions of hectares of forests in Europe, Asia and Russia in recent years and continues to expand towards Central and Western Europe. Nymphs and adults suck on leaves and cause yellowing and premature leaf drop when trees are heavily infested. The aim of the project is to document the spread of this invasive species and to survey the current infestation of oak forests in Austria and Bulgaria. The data will be complemented by laboratory experiments on the biology and ecology of the oak lace bug, in particular generation development at different temperatures and mortality rates of overwintering imagines will be investigated. This information is critical for forecasting future damage trends. In addition, insects from the field will be examined for the presence of parasitoids and pathogens that can significantly dampen population development of the pest. A key aspect of the project is the mutual exchange of information and experience between the research groups of both countries, which will allow to fill knowledge gaps on the regulation of the population dynamics of this invasive species by abiotic (e.g. temperature) and biotic factors (e.g. natural counterparts). Translated with www.DeepL.com/Translator (free version)
Research project (§ 26 & § 27)
Duration : 2021-09-01 - 2024-08-31

The aim of the project is to determine the potential for and the risk of damage to forest stands, paying particular attention to the threat posed by the proliferation of harmful organisms and abiotic damage events, through the combined use of modern remote sensing methods and innovative modeling approaches. The current mass reproduction of the bark beetle (Ips typographus) made it clear that efficient bark beetle control is not least a question of logistics. The proposed project aims to create an innovative tool for risk analysis of forest stands by linking the analysis of the predisposition of the stands, the probability of occurrence of the damaging factor and the estimation of the threat, which can be an important basis for improved logistics of damaged wood. For this purpose we use methods of ecoclimatic modeling (development of the spruce bark beetle, defensive capacity of spruce), remote sensing (stand data, current occurrence of damage) and the assessment of the supply situation. The very detailed site data from the dynamic forest typing of Styria, which are available for the first time in Austria, give the possibility to develop the models for this province in great detail and to look into the future by means of climate scenarios - as a pilot project for other provinces which will follow with the forest typing. The risk analysis tool developed in the project can thus be continuously adapted and further developed and should thus serve the users in the longer term.
Research project (§ 26 & § 27)
Duration : 2022-06-01 - 2026-05-31

Virtually all animal life depends on bacteria for survival and associations range from pathogenic to mutualistic. A good example of such interactions are bacterial endosymbionts of insects, such as Wolbachia, a ubiquitous maternally inherited microorganism which often induces reproductive manipulations in hosts like cytoplasmic incompatibility (CI). Only very few examples exist to confidently assert how endosymbionts spread through populations, i.e. Fisherian, with positive effects of host fitness or bistable with negative fitness effects where local infection frequencies tend to increase only once the infection becomes sufficiently common. The aim of this proposal is to test how the Wolbachia strain wCer2 spreads in the European cherry fruit fly, Rhagoletis cerasi, a univoltine species with a small dispersal capacity. wCer2 induces unidirectional CI, resulting in embryonic death when wCer2-infected males mate with wCer2-uninfected females. A transect between populations fixed for wCer2 and populations free of wCer2 has been described in 2015, with transitional populations showing a gradual increase of wCer2-infected individuals from south to north. This transect will be screened over ten years and the wCer2-dynamics will be determined. Fitness parameters will be elaborated and incorporated into the theoretical modelling. Furthermore, we aim to analyse the mitochondrial genome of R. cerasi from the transect populations to detect deviations from the associations of mitochondrial haplotypes and wCer2-infected individuals in transitional populations. By applying genome sequencing, we will also be able to compare the wCer1 and wCer2 genomes to detect if co-infecting Wolbachia variants positively interact. Finally, we aim to study the nuclear diversity of R. cerasi on the transect populations to study effects of wCer2 infections on the nuclear genome. Collections in Czech and German transects, PCR screenings, crossing studies, semi-field experiments and high-throughput sequencing of the host genomes and the endosymbiont genomes will provide a detailed understanding of the dynamics. The theoretical approach will test the wave modelling, besides others. Transitional populations are evolutionary hotspots to study Wolbachia dynamics and endosymbiont-host interactions. No comparable system to study the spatio-temporal spread of Wolbachia exists, and indeed, there are very few detailed data on the spread of infections in nature.

Supervised Theses and Dissertations