This year, a small number of cereal aphids (grain aphid and bird cherry–oat aphid) are undergoing tests for barley yellow dwarf virus (BYDV).

Collected from five suction traps, the results show how many of these individuals carry the virus. Results to date (10 September 2019) show that the vast majority of aphids do not carry BYDV.

The tests form part of a strategic investment in work on BYDV risk and integrated pest management (IPM) strategies in cereals.

Long-term monitoring information from the national network of suction traps shows that aphid numbers vary annually and regionally. The proportion of aphids that carry BYDV also varies between years and regions.

The test results provide a general indication of the prevalence of BYDV. However, due to the uncertainty surrounding virus pressure, there are no autumn spray thresholds for cereal aphid control.

Current advice is to consider a spray when second-generation aphids are present, irrespective of whether they carry virus or not. Based on drilling date and air temperatures, the AHDB BYDV management tool predicts when this generation is likely to be present in crops.

A team at Rothamsted Research team will use a molecular test to determine whether aphid samples (up to 90 aphids each week) carry BYDV. From next week, AHDB Aphid News will present the latest test results.

Figure 1. BYDV test results for cereal aphids at five suction trap sites: Starcross (SX), Writtle (WR), Brooms’ Barn (BB), Kirton (K) and Newcastle (N). Cumulative weekly data (7 May–10 September 2019) shown.

Download this figure in a PDF document.

As part of a UK aphid-monitoring programme, Rothamsted Research needs live peach–potato aphid samples. Typically, most samples come from oilseed rape crops in East Anglia. However, to help establish the spread of insecticide resistance in the UK, samples from other regions are required.

To submit a sample, follow the aphid sampling protocol on the Insecticide Resistance Action Group (IRAG) page ahdb.org.uk/irag