Potato Virus Y‐Transmission Efficiency of Three Aphid Species Infesting Weeds and Virus Susceptibility of Their Host Plants and Other Common Weeds

ABSTRACT Aphid species that test positive for plant viruses in reverse transcription‐PCR (RT‐PCR) analysis are not necessarily vectors. This is because virus RNA can also be detected in non‐vector aphid species using this method. Potato virus Y (PVY) has been previously detected using RT‐PCR from three common weed‐infesting alate aphid species, Aphis fukii Shinji, Aphis oenotherae Oestlund, and Capitophorus hippophaes javanicus Hille Ris Lambers, trapped in potato fields in Hokkaido, northern Japan. However, these three taxa are not known as PVY vectors, and it remains unclear whether they acquired PVY from their respective host plants or other common weeds. Therefore, we conducted two experiments: (i) transmission experiments of these aphids using Myzus persicae (Sulzer), a species widely regarded as the most efficient PVY vector, as a reference species, and (ii) virus susceptibility experiments of typical host plant species of the three aphid species and other common weed species in and around potato fields in Hokkaido. The transmission experiments showed that the PVY‐transmission efficiency of A . fukii and A. oenotherae was not significantly different from that of M. persicae . In contrast, C. hippophaes javanicus did not transmit PVY. The estimated maximum transmission efficiency by one aptera was 7.5%. Mechanical inoculations and field sampling revealed that the tested weed species were not susceptible to PVY. These findings suggest that A . fukii and A. oenotherae serve as common and efficient PVY vectors in potato fields in Hokkaido, despite their individual transmission efficiency being < 7.5%. They likely acquire PVY from infected potato plants and/or unidentified reservoirs. These novel insights can advance our understanding of PVY epidemiology in Japan and contribute to the development of more effective vector‐based control strategies against PVY.