Assessing aphids potato virus Y-transmission efficiency: A new approach.

In order to develop an alternative method to optimize the relative efficiency factor (REF) assessment, the efficiency of transmission of Potato virus Y (PVY) by seven aphid species was examined. In vitro micropropagated potato plantlets were used to experiment on phenotypically and genetically homogeneous material. Species-specific acquisition access period (AAP) on a PVY-infected plantlet was assessed for each aphid species using electrical penetration graph (EPG) technique. Aphid probing behaviour determined by EPG showed that Macrosiphum euphorbiae and Myzus persicae exhibited the shortest AAPs (15 and 11min, respectively) whereas Rhopalosiphum padi, Sitobion avenae, Brevicoryne brassicae and Acyrthosiphon pisum exhibited the longest ones (more than 30min). The transmission rate obtained for M. persicae (83.3%) was higher than the ones reported in the literature. REFs assessment showed that A. pisum and B. brassicae were poor efficient vectors while M. euphorbiae and S. avenae seemed to be efficient ones even though their respective REF were significantly lower than that of M. persicae. The species R. padi and A. fabae did not transmit PVY. The hypothesis assessed for M. euphorbiae and S. avenae and consisting in the compensation of a weak PVY-transmission efficiency by a higher number of vectors, was not supported. The use of this new method for REF evaluation and the need to consider aphid behaviour for such an assessment was discussed.