Exploiting an extraordinary case of intrasexual cuticular hydrocarbon profile dimorphism in a mason wasp, Odynerus spinipes, to shed new light on cuticular hydrocarbon genetics and evolution

• Applicants: Professor Dr. Oliver Niehuis; Professor Dr. Thomas Schmitt
• Subject Area: Evolution, Anthropology ; Evolutionary Cell and Developmental Biology (Zoology)
• Term: from 2015 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 282602688

The cuticle of insects is covered by a layer of cuticular hydrocarbons (CHCs). CHCs serve as an important desiccation barrier and have gained additional fundamental importance for communication among insects. For example, in many species, CHCs act as cues and signals for species and sex recognition. However, little is known about the genes involved in the biosynthesis of CHCs. In particular this is the case for these genes in the species-rich insect order Hymenoptera, which includes ants, bees, and wasps. In context of a DGF-funded research project, we recently discovered an extraordinary case of distinct intrasexual CHC dimorphism: females of the mason wasp Odynerus spinipes are capable of expressing two very different CHC chemotypes. These two chemotypes differ qualitatively from each other in over 70 substances. O. spinipes females with different chemotypes found at the same time and at the sample place do not differ in any non CHC-related trait, making this species an eligible and promising model for learning more about the genes involved in CHC biosynthesis. Our research project accordingly aims to identify those genes that are involved in the manifestation of the astounding CHC dimorphism in O. spinipes. To identify genes with chemotype-associated activity/expression differences, we will sequence the transcripts, and assess the transcripts' abundance as a measure of the activity of the corresponding genes, of all protein-coding genes of adult O. spinipes females of each chemotype. To demonstrate a causal link between the expression of these genes and the biosynthesis of CHCs, we intend to experimentally manipulate the expression of ten selected genes, whose expression significantly differs between females with different chemotype. We will manipulate the expression of the above genes by means of a molecular technique called RNA interference (RNAi). Our intended experiments are feasible, since we are able to raise O. spinipes under experimentally controlled conditions and have deeply sequenced the O. spinipes genome. We will compare the nucleotide and amino acid sequences of those candidate genes, whose involvement in CHC biosynthesis we were able to experimentally prove, with corresponding sequences from 21 additional vespid wasps, whose transcripts we sequenced in the international 1KITE project (http://www.1kite.org). This will allow us to also shed light on the evolutionary history of these genes and on the selective forces that have acted on them. Accompanying laboratory and field experiments will address the question of whether or not adult O. spinipes females are capable of changing their chemotype. The results from our project will consequently be of major and fundamental interest to researchers in numerous biological disciplines, ranging from chemical ecology and evolutionary genomics to speciation genetics and behavioral biology.

• DFG Programme: Research Grants