entomo.ch 2021

Annual meeting of the Swiss Entomological Society (SES) - 05.03.2021

In 2021 the traditional annual meeting of the SES, the entomo.ch, took place via Zoom.

Contact: oliver.martin@env.ethz.ch

Programme:

13.30-14.20 General assembly

14.30-15.30 keynote lecture Yuko ULRICH: "Social behaviour and disease dynamics in clonal ant colonies." (English)

15.30-15.50 Elena GIMMI & Christoph VORBURGER: "Defensive symbionts protect aphids from parasitoid wasps depending on stable genotype-by-genotype interactions." (Deutsch)

15.50-16.10 Julia LANNER, Bärbel PACHINGER & Harald MEIMBERG: "Megachile sculpturalis Smith, 1853 (Hymenoptera: Megachilidae), an Asian wild bee populates Europe." (Deutsch)

16.10-16.30 Corinne HERTÄG, Christoph VORBURGER, Mark C. MESCHER & Consuelo DE MORAES: "Homemade or take away: Where do the cuticular hydrocarbons of parasitoid wasps come from?" (English)

16.30-16.50 Patrick ROHNER, David LINZ & Armin MOCZEK: "Entwicklungsbiologische Ursachen sexueller Merkmale bei Mistkäfern: Wie macht man lange Beine?" (English)

Yuko Ulrich experimental setup ants
Yuko Ulrich experimental setup antsImmagine: copyright Yuko Ulrich

I riassunti delle presentazioni & informazioni sui presentatori:

1) Yuko ULRICH: "Social behaviour and disease dynamics in clonal ant colonies."

yuko.ulrich@env.ethz.ch; ETH Zürich, Dep. of Environmental Systems Science, Prof. Dr. Yuko Ulrich, Experimentelle Epidemiologie, CHN H75.1, Universitätstrasse 16, 8092 Zürich, Switzerland. https://www.ulrichlab.com/yuko-ulrich

Group-living is a widespread strategy, which is thought to come with particular costs and benefits. Here, I will describe recent findings on the emergence and regulation of division of labour, a proposed benefit of group-living, in ant colonies. I will then explain how we build on this work to study how social organisation can mitigate the risk of disease outbreak that is associated with group-living. This work capitalises on a new, experimentally accessible system for the study of social behaviour, the queenless, clonal raider ant Ooceraea biroi, as well as on custom tools for the automated tracking of individual behaviour and social interactions in groups.

2) Elena GIMMI & Christoph VORBURGER: "Defensive symbionts protect aphids from parasitoid wasps depending on stable genotype-by-genotype interactions."

Elena.Gimmi@eawag.ch; Eawag, Ueberlandstrasse 133, 8600 Dübendorf & D-USYS, ETH Zürich

Parasitoid wasps are among aphids’ most important natural enemies. Some black bean aphids (Aphis fabae) carry the symbiotic bacteria Hamiltonella defensa, which are able to defend their aphid hosts against the parasitoid Lysiphlebus fabarum. When multiple Hamiltonella and Lysiphlebus genotypes get exposed to each other, the combinations of symbiont genotype and parasitoid genotype determine the aphid survival probability. We added a third dimension to such a classical infection matrix experiment, by additionally varying an environmental variable: the aphid’s host plant. It allowed us to test for the presence of a genotype-by-genotype-by-environment (GxGxE) effect determining parasitism levels. However, rather than observing such a GxGxE effect, we found the symbiont-parasitoid interactions to be remarkably stable over all host plants. These results support the repeatedly suggested importance of Hamiltonella defensa as a mediator of natural coevolution between Aphis fabae and Lysiphlebus fabarum.

3) Julia LANNER(1, 2), Bärbel PACHINGER(1) & Harald MEIMBERG(1): "Megachile sculpturalis Smith, 1853 (Hymenoptera: Megachilidae), an Asian wild bee populates Europe."

julia.lanner@hotmail.com; 1) Institute for Integrative Nature Conservation Research, University of Natural Resources and Life Sciences Vienna (BOKU), Gregor-Mendel-Straße 33, A-1180 Vienna, Austria; 2) University of Berne, Hochschulstrasse 6, 3012 Berne, Switzerland

Invasive species are a severe threat for an already declining entomofauna. Monitoring programs focusing on introduced species are therefore especially critically. Performed together with the public, such programs can be implemented on a broad spatial and temporal scale. Megachile sculpturalis Smith, 1853 native to East Asia, is the first ever recorded invasive bee in Europe. The species was first observed in South France in 2008 and only two years later, the invasive bee was found in southern Switzerland. Megachile sculpturalis passed the Swiss Alps and was found in northern districts in 2013. However, it remained unclear if gaps in the documented biogeography in Switzerland and Austria reflected distribution or rather resulted from inquiry gaps. Hence, we established an international citizen science project to investigate this invasive bee. Together with public members, we collect distribution records as well as specimens to investigate its dispersal modalities, trace colonization pathways, analyze its nesting biology and competitive ability. During the last three years we gathered 150 records from Switzerland, Liechtenstein and Austria. And although we were able to close most distribution gaps in Switzerland, the detected occurrence pattern indicates multiple dispersal modalities mediated by human activities. These findings were supported by a distinctive cluster formation of different genotypes in Middle Europe. Specimens collected by our citizen scientists showed signals of multiple introduction events on the European continent. These findings might explain its invasion success and speed. However, several fundamental traits regarding its life history or biotic interaction are still unknown and remain focus of future research.

4) Corinne HERTÄG, Christoph VORBURGER, Mark C. MESCHER & Consuelo DE MORAES: "Homemade or take away: Where do the cuticular hydrocarbons of parasitoid wasps come from?"

corinne.hertaeg@usys.ethz.ch; Department of Environmental System Sciences, ETH Zürich, LFO, Schmelzbergstrasse 9, 8092 Zürich

The insect cuticle contains long-chain hydrocarbons that act as a physical barrier against pathogens and parasites but also play a central role in insect communication. The communicative functions of cuticular hydrocarbons (CHCs) are especially well documented in social insects. Ants, for example, use CHCs to recognize suitable aphid mutualists from which they collect honeydew and in return protect them from predators and parasitoids. Aphid parasitoids of the genus Lysiphlebus have evolved a chemical mimicry strategy to avoid being attacked by ants. These wasps have CHCs that are similar to those of aphis so that the ants cannot tell the two CHC profiles apart. Since CHCs can either be genetically determined and expressed by an insect, or acquired from the environment or an insect’s host, we set out to investigate where Lysiphlebus wasps get their CHCs from. We show that the linear alkanes and many long di- and trimethyl-branched compounds are homemade by the wasps, while short mono-methyl alkanes are “take away” compounds that are acquired from the aphid hosts. During behavioral experiments with aphid-tending ants, we measured their aggressivity towards wasps with different CHC profiles that were reared on different aphid hosts. We found that the homemade compounds are more important than the take away ones in this chemical mimicry system. This has important consequences for the host range of these parasitoids which not only influences their specialization, but also their potential use as biocontrol against pest aphids.

5) Patrick ROHNER, David LINZ & Armin MOCZEK: "Entwicklungsbiologische Ursachen sexueller Merkmale bei Mistkäfern: Wie macht man lange Beine?"

prohner@iu.edu; Department of Biology, Indiana University, 915 East Third Street, 102 Myers Hall, Bloomington, Indiana, 47405, United States. https://www.patrickrohner.org

Männchen und Weibchen unterscheiden sich oft nicht nur in primären Geschlechtsmerkmalen, sondern auch in diversen anderen Aspekten. Geschlechtsunterschiede in der Grösse und Form von morphologischen Strukturen leisten dabei einen beträchtlichen Beitrag zur Insektenvielfalt. Die evolutionären Kräfte die Geschlechtsunterschieden zugrunde liegen sind deshalb gut untersucht. Wie Männchen und Weibchen trotz grösstenteils geteiltem Erbgut unterschiedliche Strukturen entwickeln ist jedoch noch wenig bekannt. Wir untersuchen die entwicklungsbiologischen Grundlagen von morphologischen Geschlechtsunterschienden bei Mistkäfern bei denen Männchen aussergewöhnlich lange Vorderbeine entwickeln. Unsere Resultate zeigen dass das doublesex-Gen für die Entwicklung von Geschlechtsunterschieden nicht nur in der Größe der Merkmale, sondern auch in deren Form erforderlich ist. Da doublesex in unterschiedlichen Formen in Männchen und Weibchen vorliegt und unterschiedliche Zielgene regulieren kann, deutet dies darauf hin dass doublesex es den Geschlechtern ermöglicht trotz eines geteilten Genoms unterschiedliche Merkmale ausbilden zu können. Im Allgemeinen zeigen wir, dass die Untersuchung der Entwicklungsgrundlagen morphologischer Merkmale unser Verständnis der Evolution und Diversifizierung von Insekten fördern kann.