Deciphering aphid behaviour to evaluate phytoviruses epidemiological riskssebastien.bocquel

Non-persistent potato virus Y (PVY) transmitted by aphids causes serious damage to several cultivated plant species. From 2006 to 2009, transient aphids represented 80 to 90% of aphids trapped in potato fields of Picardie (northern France). These aphids were mainly cereal, crucifer and legume aphids, most likely associated to neighboring habitats of monitored potato fields. PVY transmission efficiency by aphids is related to the early steps involved in host plant selection process (i.e. superficial intracellular brief stings by stylets after landing on hosts) and to interplant movement ability. To evaluate the potential role of these different species in PVY epidemics we investigated, through laboratory experiments, the host plant selection process in potato aphids (Myzus persicae, Macrosiphum euphorbiae), two cereal aphids (Sitobion avenae, Rhopalosiphum padi), the pea aphid Acyrthosiphon pisum, the black bean aphid Aphis fabae and the cabbage aphid Brevicoryne brassicae. A dual choice test was developed to evaluate the aphid interplant movements and plant probing ability. All the tested species initiated a host plant selection on one plant. Only transient aphids were able to realize interplant movements. The electrical penetration graph (EPG) technique was used to investigate aphid-probing behaviour on potato plants. All the species realized superficial intracellular brief stings (i.e. potential drops) involved in PVY transmission, only colonizing potato species ingesting phloem sap. The use of aphid behaviour as a predictor of phytoviruses spreading is discussed.