LOEWE Center for
Insect Biotechnology
& Bioresources

Analytics of Chemical Defences from Insects and Insect Symbionts

Dr. Gerrit Joop

We are interested in the ecology and evolution of insects, focusing on their chemical ecology and external secretions. We also study the evolution of insect immunity, phenotypic plasticity, host–parasite interactions and resistance.


Team 2015: Andreas Mitschke, Benedikt Eickhoff, Tilottama Biswas, Thorben Grau, Sara DeLeon, Prayan Pokharel, Gerrit Joop.

Analytics of Chemical Defences from Insects and Insect Symbionts


Insects can defend themselves against parasites and predators by the secretion of e.g. toxic substances.These substances, contrary to antimicrobial peptides, are mainly small molecules and have been widely neglected in the search for e.g. antimicrobial compounds until only recently. Furthermore, whiel some insects produce these substances themselves, in other species these defensive substances are produced with the help of symbionts, mainly bacteria and fungi. Here, in a knowledge-based approach, we are testing insect defensive sescretion for additional purposes and applications. We also investigate whether these secretions are produced by the insects or their symbionts and in the latter case identify the producing symbionts using classical microbiological approaches as well as molecular approaches, including next-generation-sequencing.

Involved people: Gerrit Joop, Thorben Grau, Sara DeLeon, Andreas Mitschke
Funding: LOEWE ZIB

Selective pressure on internal vs. external immune defense in Tribolium castaneum - experimental evolution using a microsporidian and a fungal parasite


The evolution of immune defense is currently one of the most interesting topics in evolutionary biology. The combination of evolutionary immunology and host–parasite co-evolution will deepen this understanding by taking immunology back to its natural conditions. This goes hand in hand with the recently-proposed hologenome theory and the importance of microbiota. However, external immune defense in non-social organisms is another aspect of immune defense that has been largely overlooked. This is an extended defense, outside of the body, reflecting e.g. behavioral changes or the secretion of antimicrobial compounds into the environment. Especially in the latter case, individuals not only act to their own benefit, but potentially also to the benefit of their offspring and other group members. Furthermore, external and internal immune defenses should ideally interact with each other. The red flour beetle, Tribolium castaneum, secrets broadly antimicrobial substances into the flour environment, and therefore displays such an external immune defense system. Previous studies suggest that external and internal immune defenses are well balanced under natural conditions, i.e. when there are parasites in the environment. Our research therefore focuses on the following questions:

  1. Whether external immune defense is under selection by parasites, and if different parasites shift external and classical internal immune defense in different directions.

  2. How the external and internal immune defenses are balanced, and if selection by multiple parasites causes disruption or stabilization.

  3. How the balance between external and internal immune defenses is mediated, and if there is an epigenetic mechanism.

These questions are being addressed through evolution experiments using T. castaneum, a microsporidian parasite and a fungal parasite, in three different concentrations each as well as a combined parasite treatment. During this experiment, we will study one external immune parameter and several internal parameters. Experimental evolution will be followed by transcriptomic and epigenetic analysis to understand how this is mediated. Answering these questions will provide valuable insight into the evolution of immune defense strategies in an ecological context.

Involved people: Gerrit Joop, Andreas Mitschke, Tilottama Biswas
Collaborators: Philip Rosenstiel (Kiel, Germany), Joachim Kurtz (Münster, Germany), Hinrich Schulenburg (Kiel, D), Erich Bornberg-Bauer (Münster, D)
Funding: DFG SPP 1399 Host-Parasite Coevolution

Corporate and individual immunity - understanding their relationship in a non-social insect, Tribolium castaneum


Tribolium beetles excrete quinones into their flour environment. Quinones show broad antimicrobial activity, and therefore can be considered as an external immune defense. We previously showed that the production of quinones is traded-off with the internal innate immune system, and that the excretion of quinones comes at the cost of reduced larval survival. Based on these findings, we are studying the function and evolution of external immunity in detail, by addressing four main questions:

  1. Does the secretion quinones enhance beetle fitness through the manipulation of microbial diversity in the flour and the beetle gut?
  2. What are the causes and consequences of trade-offs between external immunity and other aspects of immunity?
  3. How is quinone production regulated?
  4. Does external immunity represent a true corporate trait that benefits a group of unrelated individuals?

Involved people: Gerrit Joop, Andreas Mitschke, Prayan Pokharel
Collaborators: Hinrich Schulenburg (Kiel, D), Philip Rosenstiel (Kiel, D), Stanislav Gorb (Kiel, D), Arne Traulsen (MPI Plön, D) und Joachim Kurtz (Münster, D)
Funding: Volkswagenstiftung