Jacobaea vulgaris interactions

 

We compare aboveground and belowground communities associated to the plant ragwort (Jacobaea vulgaris) and study how the diversity of the plant community affects these multitrophic communities, and the behaviour of individuals in these communities. We aim to disentangle the importance of host plant quality and of characteristics of the surrounding plant community for aboveground and belowground interactions.

 

 


 

Using plant-insect-microbe interactions to strengthen biological control of the highly invasive weed Jacobaea vulgaris

Jacobaea vulgaris (common ragwort) is a highly invasive and toxic plant species native to Eurasia. Both in its native and in its invaded range it spreads quickly in abandoned or poorly managed fields, reducing biodiversity and causing harm to the livestock that grazes on these pastures. In the invaded range control efforts focus on biological control with highly specialized herbivores like the moth Tyria jacobaeae. However, biological control has so far failed to provide complete control of J. vulgaris, and it often needs to be combined with less specific and sustainable methods, like herbicide application or mechanical removal. There is an urgent need to improve control of common ragwort in an environmentally friendly and specific way. The aim of this research is to improve the efficacy of T. jacobaea at reducing common ragwort populations by combining the release of this insect species with the application of microbes that boost their impact on common ragwort.

Plants and insects are hosts to a diverse and rich group of microbes, which make up their microbiome. Each component of the microbiome can have a direct positive or negative impact on their host, for instance promoting plant growth or increasing the ability of an insect to acquire nutrients. Moreover, the microbiome has a crucial function in modulating the interactions between plants and herbivore insects. Some insect symbionts can increase insect fitness on particular plant species by helping them overcome plant defenses. On the other hand, some components of the plant microbiome alter plant resistance to herbivory. Microbes can induce plant systemic resistance or produce insecticidal toxins, thus making plants more resistant to herbivores; but they can also increase their susceptibility to insect feeding, for instance by downregulating plant defenses to herbivory. Obtaining a thorough understanding of how particular microbial strains modulate the interactions of specific plant-insect systems could be harnessed to steer these interactions towards a desired state that benefits either the insect or the plant species. In the particular case of this project, the identification of microbial strains that can be combined with herbivory by T. jacobaeae to reduce the fitness of common ragwort plants in a synergistically way would provide an exciting new tool to fight common ragwort invasions. Additionally, the knowledge acquired through this research will be key to understand the complex set of interactions between plants, aboveground insect herbivores and the microbiomes of both from a fundamental perspective.