Impact of host and plant phylogenies on parasitoid host range

Host specificity of parasitoids is a key trait reflecting their functional role in ecosystems. It is thought to be shaped by phylogenetic relationships among potential host species and those plants bearing the hosts. However, the respective importance of these phylogenetic signals in the host range of the parasitoid has been scarcely described. In this context, we evaluated the effect of phylogenetic (and taxonomic) signals of plants and host species on parasitoid host range (assessing parasitoid ability to produce offspring) in three aphid parasitoids (Aphelinus abdominalis, Aphidius ervi and A. rhopalosiphi) exposed to 16 plant-aphid complexes encompassing their ecological host range. The parasitoids were all categorized as oligophagous species and a phylogenic signal was detected in plant and aphid species phylogenies for A. rhopalosiphi and A. abdominalis host ranges, respec-tively. Aphelinus abdominalis specialized on aphids belonging to the Dactynotine subtribe and A. rhopalosiphi on species feeding on Poaceae. By contrast, no cluster was detected in the host range of A. ervi. Similar results were found when considering taxonomic signals, suggesting that taxonomic data are equally useful for assessing parasitoid host specificity. Identifying phylogenetic (or taxonomic) signals that dictate parasitoid host specificity could be useful for detecting non-target species at risk in the framework of classical biological control programs and targeting pest species in the context of such programs.