Responsabilité(s) collective(s)
Sujet : The role of transposable elements in the invasive success of Harmonia axyridis
Dates : 1er mars 2022 – 31 mai 2024
Responsables CBGP : M. Gautier & A. Estoup
Harmonia axyridis, or how it is normally named, the harlequin ladybug, was originated in eastern Asia, and during the 20th century was purposely introduced in North America and Europe to act as a biological control. However, it expanded too quickly and some years later it was considered an invasive species both in North America and Europe. Nowadays this species is present worldwide except in the Antarctica and other few countries. Because of this, H. axyridis is now considered as a model species for studying biological invasions. This invasion caused negative ecological and socio-economic impacts in its invaded areas. It is now considered a top predator which can affect aphidophagous guilds, and which has already impact on the native ladybirds’ populations. In the economic aspect, H. axyridis is an important contamination pest in wine grape production where it releases chemical compound which are unpleasant in the wine.
Transposable elements, or TEs, are mobile DNA sequences capable of replicating themselves within genomes, independently of the host cell DNA. They are virtually present in all eukaryotic genomes in a very wide variable proportion: from 1 to 90%. They have a very strong potential to affect gene expression since it has already been shown that they respond to abiotic and biotic stress conditions contributing to host genome evolution and host genome adaptation.
The main objective of this project is to study the role of transposable elements in the invasive process of H. axyridis worldwide. For this purpose, we are working on a de novo TE library in this species. During the first part of the pipeline, we search for de novo insertions in all the 7 H. axyridis assemblies using the software RepeatModeler2, whose new version includes a module specifically for one part of TE types: LTRs. The second part is the TE library manual curation process, which is based on the Goubert et al. 2022 pipeline.
Mots-clés : Population genetics, transposable elements, Harmonia axyridis, invasive species, insects
