Group Menzel

Evolutionary Chemical Ecology and Biotic Interactions

Currently, our research group focuses on three topics:

  • Evolutionary ecology of insect cuticular hydrocarbons
  • Behavioural traits and their role for biotic interactions
  • Insect ecology and conservation

Evolutionary ecology of insect cuticular hydrocarbons – linking physics, chemistry and biology

Imagine you have to design a material that is waterproof, can be used as lubricant, enhances attachment to smooth surfaces, and has such a unique odour that you can use it to communicate your identity to another individual and attract a partner. Moreover, it should repair itself if damaged, and ideally should work at all kinds of temperatures. How should such a material be composed, and what material properties should it have?

A daunting task – but all insects have exactly that: a thin waxy layer of cuticular hydrocarbons (CHCs) covering their body surface like a multifunctional suit. Although 100 times thinner than a sunscreen film on your skin, it fulfils all of the above functions. How can this layer fulfil all the functions at the same time? Why is the chemical composition of insect hydrocarbon films so complex, with up to 100 different compounds? And which selection pressures led to such an astonishing chemical diversity across species?

How is multifunctionality achieved on a physical level?

All the biological functions of the CHC layer and possible conflicts between them depend mainly on their physical properties, but these are poorly understood. Waterproofing relies on solid or high-viscosity compounds, but the other functions require them in a more fluid state. We believe that cuticular lipid layers can meet these conflicting needs due to their complex phase behaviour and other physical properties, and that insects can tune these to different demands by varying their chemical composition.

Our team studies the multifunctionality of insect cuticular hydrocarbons by integrating physical chemistry, physiology and evolutionary ecology. By combining various techniques for measuring physical properties of hydrocarbon layers with biological experiments on insects, we determine how lipid composition, phase state and physical properties affect each function. To this end, we collaborate with physicists and biomechanists from Mainz (Svenja Morsbach), Cambridge (Walter Federle), Paris (Bérengère Abou), Zurich (Dimitris Tsalikis), Patras (Greece) (Vlasios Mavrantzas) and Fukuoka (Japan) (Fumitoshi Kaneko).

How does the CHC layer help to cope with climate change?

A focus of our group is how CHC layers protect against desiccation. Phase behaviour is temperature-dependent. This is why insects need to adjust CHC composition to the current climate conditions. We study how insects do that, and what consequences it has, for their drought resistance on one hand, and for the CHC biophysics on the other hand. So far, it seems that species, and potentially also conspecific populations, differ in their ability to acclimate – and this will have strong implications for the species’ ability to survive in a changing climate.

Even apart from climate change, the CHC layer is linked to an insect's ecological niche. Some micro-habitats or activity periods (day vs night, for example) result in higher or lower desiccation risk. This is likely reflected in the insect's CHC layer, which we currently study in tropical ants and in Central European grasshoppers.

How do insects produce such a complex CHC layer?

CHC profiles can evolve rapidly, and even closely related species can have completely different CHC profiles. Also within a species, castes or sexes differ greatly in their CHC composition. How do insects manage to biosynthesise such complex CHC profiles, and why can they evolve so fast?

Through a comparative genomics approach of 26 species across the Hymenopteran tree, we investigate the evolution of gene families plus the evolution of the underlying gene regulatory networks associated to this pathway. This will allow us to elucidate the importance and interplay of various putatively involved mechanisms such as gene duplication, transposable elements, alternative splicing, DNA methylation, and co-expressed gene networks. This project is done in collaboration with Barbara Feldmeyer (Frankfurt), Oliver Niehuis (Freiburg), Volker Nehring (Freiburg), Jan Büllesbach (Münster), and Thomas Schmitt (Würzburg).

How do CHCs shape biotic interactions?

Cuticular hydrocarbons essentially form the language of ants – no other signal is so important for communication within the colony and beyond. CHCs are vital to organise the division of labour in a colony, both between queen and workers, and between different task groups among workers (e.g. nurses and foragers). But they also shape a surprisingly large variety of interspecific interactions. Check out my article in Myrmecological News blog, where I show how fascinating and diverse CHC-mediated biotic interactions are. Currently, we investigate how ant CHCs influence interactions and coevolution with social parasites (collaboration with Susanne Foitzik), and with other ant species. When insects walk, they inevitably leave chemical traces on the ground – so-called chemical footprints (which are completely different from trail pheromones!). They consist of hydrocarbons and are largely congruent with CHCs. Using these footprints, ants can sense where other ants walked – and exploit this information to their benefit  (PhD project Vanessa Menges). Finally, CHCs influence interactions of insect prey with spider predators - because CHCs adhere to spider webs of certain spider species, and this is why insects get stuck in the first place. Here, the physical properties of CHCs determine the forces with which the insect prey is ‘glued’ into the spider web. We investigate this fascinating interaction using chemical analyses, biological experiments, and biophysical measurements (PhD project Lucas Baumgart, collaboration with Anna-Christin Joel, Aachen),

Behavioural traits and their role for biotic interactions

Beside chemical traits, I am interested in how other traits mediate niche differentiation, but also social, competitive and other interactions among organisms. An important, but rarely considered set of traits is behaviour. Behavioural traits such as aggression and exploration mediate competitive interactions within and among species. Currently, we investigate how these traits vary with environmental variation, and how they may shape competitive interactions.

  • PhD project of Vanessa Menges
  • Bachelor theses of Luca Kunze, Christina Duthel

Insect ecology and conservation

Insects are declining massively. Together with Daniel Dreesmann (Biology didactics, Mainz), we therefore created the Interactive Insect Campus. This project combines innovative teaching formats (digital and offline) and other forms of environmental education with practical insect conservation on campus. This way, we want to create small habitats for insects all over the campus of our university. At the same time, we want to pass on our passion for insects to students, employees and visitors. For example, we are creating the I²-Campus infotrail with a number of stations that explain various aspects of insects and their ecology. In this context, we also survey the insect fauna on the JGU campus, and offer excursions.

To further elucidate causes of insect decline, we collaborate with the Natural History Museum of Mainz. When pollinators visit a flower, they retain a lot of pollen on their body. This pollen can be recovered even from decades-old museum specimen. Currently, we collect this pollen from hoverflies from older collections. Using pollen metabarcoding, we try to reconstruct our flora from 30 and 40 years ago, and compare it to current plant communites (collaboration with Alexander Keller, Munich, as well as Bernd Herkner and Carsten Renker, Natural History Museum of Mainz).

We also study how insect communities are structured by niche differentiation. Currently, we investigate how ants of the Amazon rainforest in Perú are structured into different niches. These niches include dietary differentiation, but also the daily activity period (dawn, noon, dusk, midnight), arboreal or terrestrial foraging, nesting close to a creek or not, and others. Many of these niches are linked to desiccation resistance, because some niches lead to warmer or drier microclimate than others.

  • Bachelor thesis of Juliana Hastamorir Torres

GROUP MEMBERS

Group leader

PhD students / scientific employees:

  • Selina Huthmacher (Biophysical and functional consequences of cuticular hydrocarbon variation in ants)
  • Sascha Schlüter (The role of lipid physical properties for the multifunctionality of insect cuticular hydrocarbons)
  • Shadi Karimifard (Genomic and gene regulatory basis of rapid evolutionary diversification of a multifunctional trait) (co-supervisor Barbara Feldmeyer)

Bachelor students:

  • Carl Vitting
  • Juliana Hastamorir Torres
  • Luca Kunze
  • Christina Duthel
  • Leonidas Zein
  • Mathilda Wiederänders (co-supervised with Dr. Jörn Buse, NP Schwarzwald)

Former Postdocs and PhD students: