Co-evolution and symbiont replacement shaped the symbiosis between adelgids (Hemiptera: Adelgidae) and their bacterial symbionts
Article first published online: 24 FEB 2012
© 2012 Society for Applied Microbiology and Blackwell Publishing Ltd
Volume 14, Issue 5, pages 1284–1295, May 2012
How to Cite
Toenshoff, E. R., Gruber, D. and Horn, M. (2012), Co-evolution and symbiont replacement shaped the symbiosis between adelgids (Hemiptera: Adelgidae) and their bacterial symbionts. Environmental Microbiology, 14: 1284–1295. doi: 10.1111/j.1462-2920.2012.02712.x
- Issue published online: 18 APR 2012
- Article first published online: 24 FEB 2012
- Received 21 November, 2011; revised 19 January, 2012; accepted 24 January, 2012.
The Adelgidae (Insecta: Hemiptera), a small group of insects, are known as severe pests on various conifers of the northern hemisphere. Despite of this, little is known about their bacteriocyte-associated endosymbionts, which are generally important for the biology and ecology of plant sap-sucking insects. Here, we investigated the adelgid species complexes Adelges laricis/tardus, Adelges abietis/viridis and Adelges cooleyi/coweni, identified based on their coI and ef1alpha genes. Each of these insect groups harboured two phylogenetically different bacteriocyte-associated symbionts belonging to the Betaproteobacteria and the Gammaproteobacteria, respectively, as inferred from phylogenetic analyses of 16S rRNA gene sequences and demonstrated by fluorescence in situ hybridization. The betaproteobacterial symbionts of all three adelgid complexes (‘Candidatus Vallotia tarda’, ‘Candidatus Vallotia virida’ and ‘Candidatus Vallotia cooleyia’) share a common ancestor and show a phylogeny congruent with that of their respective hosts. Similarly, there is evidence for co-evolution between the gammaproteobacterial symbionts (‘Candidatus Profftia tarda’, ‘Candidatus Profftia virida’) and A. laricis/tardus and A. abietis/viridis. In contrast, the gammaproteobacterial symbiont of A. cooleyi/coweni (‘Candidatus Gillettellia cooleyia’) is different from that of the other two adelgids but shows a moderate relationship to the symbiont ‘Candidatus Ecksteinia adelgidicola’ of A. nordmannianae/piceae. All symbionts were present in all adelgid populations and life stages analysed, suggesting vertical transmission from mother to offspring. In sharp contrast to their sister group, the aphids, adelgids do not consistently contain a single obligate (primary) symbiont but have acquired phylogenetically different bacterial symbionts during their evolution, which included multiple infections and symbiont replacement.