An improved detection method for the Rhopalosiphum padi virus (RhPV) allows monitoring of its presence in aphids and movement within plants.

Rhopalosiphum padi virus (RhPV) is an insect RNA virus that infects aphids, reducing their lifespan and fecundity. It can be transmitted vertically between aphids and horizontally via the plant. An improved detection method for the virus in aphids and plants using RT-PCR was developed; this allowed individual aphids to be tested for RhPV. Testing of R. padi aphids collected from different sites in Sweden revealed the presence of RhPV in wild aphid populations for the first time in Europe. Virus could be detected in several life stages of R. padi, including sexual individuals and eggs, establishing an over-wintering route for the virus. Using RT-PCR, systemic transport of the virus in plants was tracked. Virus spread from the aphid feeding site to all parts of the plant, including roots, within 7 days, and could be acquired by virus-free aphids feeding on the same plant.