Functional insights from the GC-poor genomes of two aphid parasitoids, "Aphidius ervi" and "Lysiphlebus fabarum

authors

• Dennis Alice
• Ballesteros Gabriel
• Robin Stéphanie
• Schrader Lukas
• Bast Jens
• Berghöfer Jan
• Beukeboom Leo
• Belghazi Maya
• Bretaudeau Anthony
• Buellesbach Jan
• Cash Elizabeth
• Colinet Dominique
• Dumas Zoé
• Errbii Mohammed
• Falabella Patrizia
• Gatti Jean-Luc
• Geuverink Elzemiek
• Gibson Joshua
• Hertaeg Corinne
• Hartmann Stefanie
• Jacquin-Joly Emmanuelle Joly
• Lammers Mark
• Lavandero Blas
• Lindenbaum Ina
• Massardier-Galatà Lauriane
• Meslin Camille
• Montagné Nicolas
• Pak Nina
• Poirié Marylène
• Salvia Rosanna
• Tagu Denis
• Tares Sophie
• Vogel Heiko
• Schwander Tanja
• Simon Jean-Christophe
• Figueroa Christian
• Vorburger Christoph
• Legeai Fabrice
• Gadau Jürgen
• Smith R.Chris

keywords

• DNA methylation loss
• GC content
• Lysiphlebus fabarum
• Parasitoid wasp
• Toll and Imd pathways
• Venom proteins
• De novo genome assembly
• Aphid host
• Aphidius ervi
• Chemosensory genes

abstract

Background: Parasitoid wasps have fascinating life cycles and play an important role in trophic networks, yet little is known about their genome content and function. Parasitoids that infect aphids are an important group with the potential for biological control. Their success depends on adapting to develop inside aphids and overcoming both host aphid defenses and their protective endosymbionts. Results: We present the de novo genome assemblies, detailed annotation, and comparative analysis of two closely related parasitoid wasps that target pest aphids: Aphidius ervi and Lysiphlebus fabarum (Hymenoptera: Braconidae: Aphidiinae). The genomes are small (139 and 141 Mbp) and the most AT-rich reported thus far for any arthropod (GC content: 25.8 and 23.8%). This nucleotide bias is accompanied by skewed codon usage and is stronger in genes with adult-biased expression. AT-richness may be the consequence of reduced genome size, a near absence of DNA methylation, and energy efficiency. We identify missing desaturase genes, whose absence may underlie mimicry in the cuticular hydrocarbon profile of L. fabarum. We highlight key gene groups including those underlying venom composition, chemosensory perception, and sex determination, as well as potential losses in immune pathway genes. Conclusions: These findings are of fundamental interest for insect evolution and biological control applications. They provide a strong foundation for further functional studies into coevolution between parasitoids and their hosts. Both genomes are available at https://bipaa.genouest.org.

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