An estimate of the likelihood that aphids will transmit non-persistent potato viruses (e.g. PVY) in the field can be made using the data collected by the aphid suction traps. This estimate, the aphid vector pressure, is calculated by summing the total catch of each aphid species, after multiplication by a factor estimating the efficiency of that species as a vector of PVY. Details of the vector efficiencies used in these calculations are available via the AHDB (Potatoes) Aphid Monitoring webpages. The vector pressure is a very coarse measure of the likelihood of virus transmission. Numerous factors will influence virus transmission, including complex interactions between aphid species and the strain of virus they transmit.
The predicted early start to the aphid flight season due to mild winter temperatures was observed. The total number of aphids known to vector potato viruses that have been caught in the Dundee and Edinburgh suction traps up to the week ending 16 June is now 861. This figure ranks third of the last 10 years (behind 2017).
The total of 861 aphids includes 465 Willow-Carrot aphids (Cavariella aegopodii), 93 Leaf-Curling Plum aphids (Brachycaudus helichrysi) and 72 Shallot aphids (Myzus ascalonicus) making up 54%, 11% and 8% respectively of the total aphid vectors caught. 59% of the total number of aphids have been caught in the Edinburgh trap and 41% at Dundee.
The cumulative aphid vector pressure for 2019 (up to 16 June) at Edinburgh now ranks 5th over the last 32 years. The Willow-Carrot aphid (Cavariella aegopodii) is responsible for 70% of the accumulated pressure, with the Leaf-Curling Plum aphid (Brachycaudus helichrysi) and the Shallot aphid (Myzus ascalonicus) accounting for 5% and 4% respectively.
The cumulative aphid vector pressure for 2019 (up to 16 June) at Dundee ranks 5th over the last 32 years. The Willow-Carrot aphid is responsible for 57% of this value, the Leaf-Curling Plum aphid is responsible for 6% and the Bird Cherry-Oat aphid (Rhopalosiphum padi) accounts for 6%.