Molecular phylogeny reveals the existence of two sibling species in the aphid pestBrachycaudus helichrysi(Hemiptera: Aphididae)

Abstract

Piffaretti, J., Vanlerberghe‐Masutti, F., Tayeh, A., Clamens, A.‐L., Cœur d’Acier, A. & Jousselin E. (2012). Molecular phylogeny reveals the existence of two sibling species in the aphid pestBrachycaudus helichrysi(Hemiptera: Aphididae). —Zoologica Scripta,41, 266–280.Brachycaudus helichrysiis a worldwide polyphagous aphid pest that seriously damages its primary hosts (Prunusspp.) and the various cultivated plants among its secondary hosts (e.g. sunflower). A recent study of theBrachycaudusgenus suggested that this species might encompass two differentiated lineages. We tested this hypothesis, by carrying out a phylogenetic study of this aphid pest based on worldwide sampling and the evaluation of mitochondrial, nuclear andBuchnera aphidicolaDNA markers. We show that this species is actually an amalgamation of two sibling taxa,B. helichrysiH1 andB. helichrysiH2, that seem to have overlapping geographic ranges and herbaceous host plant preferences. These two taxa displayed levels of genetic divergence as great as those generally found between sister species in theBrachycaudusgenus, suggesting that they actually correspond to two distinct species. Our phylogenetic reconstructions revealed a degree of incongruence between the topologies obtained with the aphid gene data set and with data for a DNA marker from its primary endosymbiont. We identified possible reasons for this observation and discuss the ecological and genotypic data suggesting thatB. helichrysiH1 andB. helichrysiH2 have different life cycles.