From midsummer onwards, the cereal aphids usually dominate the Scottish aphid bulletin and significantly affect the index that is used to estimate the vector pressure for aphid-transmitted potato viruses. Three species, the Rose-Grain aphid (Metopolophium dirhodum), the Grain aphid (Sitobion avenae) and the Bird Cherry-Oat aphid (Rhopalosiphum padi), are known to be vectors of non-persistently transmitted potato viruses (e.g. PVY) and because they can occur in high numbers in the suction traps, each individual species can make a relatively high contribution to the overall aphid vector pressure index. SASA have conducted field trials that support the role of cereal aphids, particularly the Rose-Grain aphid and the Grain aphid, in virus transmission.
As would be expected, cereal aphids are also important pests of cereal crops, causing direct damage by feeding on crops and through the transmission of viruses such as barley yellow dwarf virus (BYDV).
First flight predictions for season 2025
Based on the mean temperatures over January and February 2025, the following first flight predictions and numbers by 1st July are provided by Rothamsted Research (found at Aphid Forecast | Insect Survey):
- Rose-Grain aphid (Metopolophium dirhodum) – 18 May for Edinburgh (75% confidence limits: 25 April – 11 June) and 29 May for Dundee (75% confidence limits: 6 May - 21 June). Total numbers by 1st July are predicted to be 40 individuals for Edinburgh (75% confidence limits: 6 to 236) and 27 for Dundee (75% confidence limits: 2 to 218).
- Grain aphid (Sitobion avenae) – 23 May for Edinburgh (75% confidence limits: 3 May – 13 June) and 31 May for Dundee (75% confidence limits: 13 May – 18 June). Total numbers by 1st July are predicted to be 24 individuals for Edinburgh (75% confidence limits: 5 to 109) and 20 for Dundee (75% confidence limits: 3 to 116).
- Bird Cherry-Oat aphid (Rhopalosiphum padi) – 11 May for Edinburgh (75% confidence limits: 21 April – 1 June) and 13 May for Dundee (75% confidence limits: 26 April – 1 June). Total numbers by 1st July are predicted to be 56 for Edinburgh (75% confidence limits: 11 to 266) and 41 for Dundee (75% confidence limits: 4 to 361).
Cereal aphids and PVY transmission in 2024 into 2025
Although there was higher than average activity early in the 2024 season, cereal aphid numbers didn't increase as expected over the summer peak season, leading to below than average catch numbers by the end of the cropping year.
It is anticipated that the incidence of plants showing mosaic symptoms in 2025 will remain relatively high. Aphid activity in 2025 is expected to be approximately one to three weeks early and could potentially lead to higher than seasonal averages. Therefore, a balanced approach to the management of non-persistent viruses and their vectors, with heightened vigilance towards aphid activity and sources of virus, will be required based on the information currently available for the 2025 summer.
Potato varieties that have been revealed by virus testing of leaf samples collected during classification inspections as particularly prone to the acquisition of PVY include King Edward, Harmony, Shepody, Maris Peer and Nicola.
Cereal aphids in 2025
Cereal aphid activity started early this year, with the first individual caught in Edinburgh during the week beginning 17 March and numbers steadily increasing through April and May. The period of very warm weather during the spring has likely expedited aphid development and the first flights of all cereal aphid species have been 2-3 weeks earlier than predicted (apart from M. dirhodum which was 8 weeks early).
As the Inverness trap only started trapping in April 2019, we currently report on Edinburgh and Dundee catches only.
Please note that the graphs below represent actual numbers of aphids caught in these two east coast suction traps using a log scale. Viewing population data on a log scale makes it easier to spot subtle changes in early season numbers when comparing previous years for species with high seasonal peak numbers.
Rose-Grain aphid in 2025
The first Rose-Grain aphid (Metopolophium dirhodum) was caught in the Edinburgh suction trap during w/b 17 March, around 8 weeks earlier than predicted and outwith the 75% confidence limits. The first Rose-Grain aphid caught at Dundee was on 21 April, around 5 weeks early.
The cumulative total as of 24 August is 666, ranking 23rd over the last 39 years of trapping.
52% of the cumulative total has been caught at Dundee; 48% at Edinburgh.
Grain aphid in 2025
The first Grain aphid (Sitobion avenae) was caught in Edinburgh on 5th May and in Dundee on 21st May - both within the predicted 75% confidence limits.
The cumulative total up to 24 August is 220, ranking 36th over the last 39 years of trapping.
61% of this cumulative total was caught at Dundee; 39% at Edinburgh.
Bird Cherry-Oat aphid in 2025
The first Bird Cherry-Oat aphid (Rhopalosiphum padi) in 2025 was caught in Edinburgh on 22nd April and in Dundee on 27th April.
The cumulative total up to 24 August is 2432, ranking 20th out of the last 39 years.
42% of this cumulative total was caught at Dundee; 58% at Edinburgh.
Apple-Grass aphid in 2025
The first Apple-Grass aphids (Rhopalosiphum oxyacanthae) were caught in both Edinburgh and Dundee on 30 April.
The cumulative total up to 24 August is 3036, ranking 3rd out of the last 39 years.
20% of this cumulative total was caught at Dundee; 80% at Edinburgh.
SASA