This year, the Thuringian Forest is not the only one to be affected by a major bark beetle infestation, which is killing many spruce trees and will ultimately change the entire forest ecosystem in the future. This is primarily due to the drought caused by global warming and the lack of diversity in most of our native forests. However, we also find that there are still many unanswered scientific questions about the basics of bark beetle infestation, such as which trees are affected and why.
In our department we are trying to find answers to these questions. For example, we are investigating the exact relationships from the tree's point of view. We are interested in why, despite the mass reproduction of the spruce bark beetle (Ips typographus), some spruce trees (Picea abies) in the forest are preferentially attacked while others are not. To do this, we create genetically modified trees and alter the composition of the tree resin, which is the main defense mechanism of the spruce, as well as the bouquet, which plays a crucial role in finding attractive trees for the bark beetle. We then test how the beetles respond to these changes in the laboratory.
At the same time, we are trying to gain new insights into the bark beetle. It does not live alone, but in symbiosis with a variety of microorganisms. For example, it harbors a large number of fungi on its body surface, which probably play an important role in the digestion of food. In addition, the beetle's gut contains a complex mix of specialized bacteria that primarily break down the tree's toxic antibodies, making the food more digestible for the beetle. To confirm these hypotheses, and ultimately to better understand this complex system, we are trying to identify the chemicals involved and are also testing the beetles' interactions with fungi and bacteria in our labs. To gain further insight into this symbiotic system of beetles, fungi and bacteria, we are also using the slightly larger and easier to keep large pine weevil (Hylobius abietis). Although this beetle feeds only on the bark of young trees, it is likely to have a comparable community of fungi and bacteria, since it is confronted with the same substances and defenses of the tree as the spruce bark beetle.
In addition to the latest research results, we will present the organisms to be studied, such as transgenic spruces, spruce bark beetles, spruce weevils and their fungi and bacteria, as well as some of the experimental set-ups to be used for laboratory tests.
