Herbivores of the tree of heaven along a spatial rural-urban gradient in Freiburg by Michele Deis Part of Bachelor thesis at the Albert-Ludwig University Freiburg In November 2015 Supervisor: Dr. Gesine Pufal For the course „Academic Skills & Forests Sciences“ © Michele Deis
3rd most invasive species in Europe Ailanthus altissima = Tree of heaven Introduced in Germany 1751 abundant in urban environments & transport corridors efficient sexual reproduction, clonal growth, pollution tolerance causes health issues, economical damage & changes ecosystems © Michele Deis
How to control? manual, mechanical and chemical methods biological control??? Required to study potential herbivores and enemies
In previous studies: 46 phytophagus anthropod species in China 2 insects species & generalist herbivore snail in Europe mulberry moth ailanthus silk moth white-lipped snail
Enemy Release Hypothesis (ERH) Introduced plants in non-native regions are decreasingly regulated by herbivores and other natural enemies ensuing a rapid spread in distribution and abundance No general validity
Research Question Is there a change in the richness of herbivorous insect species, that feed on A. altissima along a rural-urban gradient? With other words: connection between the richness of insect herbivores to the rural-urban gradient in Freiburg
Methods Study site: Herbivor sampling: 35 trees on rural-urban gradient rural-urban gradient = in ArcGis with buffer tool 25m Buffer around each location & percentages of sealed and unsealed area recorded Herbivor sampling: Insect collecting using a beating tray & identification Statistical analysis in software “R”
Herbivor Sampling Results No herbivores on 43% of trees 55 individuals of 27 species: 16 aphids species 11 other insect species
Distribution of insect herbivores no significant (p-vaulue= 0,385) effect
Conculsion No connection between richness of insect herbivores to rural-urban gradient ERH is valid 27 potential herbivore species
Biological control??? My study: Study potential herbivores Further research: Herbivor damage of these potential herbivores? More research is needed!
Take away No connection between richness of insect herbivores to rural-urban gradient ERH is valid 27 potential herbivore species Fitness for biological control more research is needed