Sawfly Genomes Reveal Evolutionary Acquisitions That Fostered the Mega-Radiation of Parasitoid and Eusocial Hymenoptera

Genome Biol Evol. 2020 Jul 1;12(7):1099-1188. doi: 10.1093/gbe/evaa106.


The tremendous diversity of Hymenoptera is commonly attributed to the evolution of parasitoidism in the last common ancestor of parasitoid sawflies (Orussidae) and wasp-waisted Hymenoptera (Apocrita). However, Apocrita and Orussidae differ dramatically in their species richness, indicating that the diversification of Apocrita was promoted by additional traits. These traits have remained elusive due to a paucity of sawfly genome sequences, in particular those of parasitoid sawflies. Here, we present comparative analyses of draft genomes of the primarily phytophagous sawfly Athalia rosae and the parasitoid sawfly Orussus abietinus. Our analyses revealed that the ancestral hymenopteran genome exhibited traits that were previously considered unique to eusocial Apocrita (e.g., low transposable element content and activity) and a wider gene repertoire than previously thought (e.g., genes for CO2 detection). Moreover, we discovered that Apocrita evolved a significantly larger array of odorant receptors than sawflies, which could be relevant to the remarkable diversification of Apocrita by enabling efficient detection and reliable identification of hosts.

Keywords: hexamerin; major royal jelly protein; microsynteny; odorant receptor; opsin; phytophagy.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Conserved Sequence
  • DNA Transposable Elements
  • Female
  • Gene Dosage
  • Genetic Speciation*
  • Genome, Insect*
  • Glycoproteins / genetics
  • Herbivory / genetics
  • Host-Parasite Interactions / genetics*
  • Hymenoptera / genetics*
  • Immunity / genetics
  • Insect Proteins / genetics
  • Male
  • Multigene Family
  • Receptors, Odorant / genetics
  • Social Behavior
  • Vision, Ocular / genetics


  • DNA Transposable Elements
  • Glycoproteins
  • Insect Proteins
  • MRJP1 protein, Apis mellifera
  • Receptors, Odorant
  • storage proteins, Insecta