Comparison of Potato virus Y and Plum Pox Virus transmission by two aphid species in relation to their probing behavior

Two different aphid species, Myzus persicae (Sulzer) and Hyalopterus pruni (Geoffroy) (Homoptera: Aphididae), were used to analyze their ability to transmit two different potyviruses, Potato virus Y (PVY) and Plum pox virus (PPV), to pepper (Capsicum annuum) and Nicotiana benthamiana plants, respectively. In parallel experiments, M. persicae consistently transmitted both viruses with high efficiency, whereas H. pruni always failed to transmit either virus. This is in contrast to previous reports describing H. pruni as a vector of these potyviruses. Different aphid probing behavior among individual aphids of each species was obtained in electrical penetration graph (EPG) experiments performed on pepper plants. This suggested that H. pruni did not transmit these potyviruses due to behavioral differences during probing that impeded virus acquisition and/or inoculation. It was found that M. persicae usually makes its first probe within the first 2 min, whereas H. pruni individuals remained for more than 10 min on the plant before starting to probe. Furthermore, M. persicae individuals displayed their first intracellular puncture during the first minute of probing whereas H. pruni needed similar to 15 min to penetrate the cell plasmalemma with their stylets. In addition, intracellular stylet punctures occurred very frequently for M. persicae but was a rare event, never exceeding a single one, for H. pruni. The relevance of these findings for the epidemiological spread of potyviruses by different aphid species is discussed.