Unravelling the complex interaction of cereal aphids and the virus they vector
A greater understanding about the interplay between virus strain, insect vector, timing of infection, weather and barley genetics, and their impact on yield loss is needed if we are to advance decision support tools for control of BYDV. Louise McNamara, Teagasc Entomologist, tells us more.
Control of cereal aphids and the Yellow Dwarf Viruses (YDV) they vector is becoming increasingly challenging due to insecticide resistance, loss of insecticides, pesticide reduction targets and changing climate. Integrated Pest Management strategies built upon excellent monitoring networks, a greater understanding of aphid behaviour and virus transmission, and improved plant genetics offer hope to the sector in addressing the challenge.
There are many species of cereal and barley yellow dwarf virus, and each is transmitted by different aphids with variation in transmission efficiency. We surveyed barley crops throughout Ireland in 2021 and 2022 using DNA sequencing technology. This uncovered a greater diversity of BYDV strains than previously thought. While the most prevalent species identified was BYDV-MAV, which was observed in all field samples, BYDV-PAV and BYDV-PAS strains were also identified, but less frequently.
As a direct result of this work, we have been able to develop improved molecular surveillance tools, now being used in new Teagasc research, testing different aphid monitoring methods to determine the most appropriate approach individual growers can use to assess risk of aphid and BYDV to their crops.
This is being supported by research into how effectively these BYDV strains, typically found in Ireland, are transmitted by different aphids; including grain aphids with the knock-down resistance. Encouragingly, our research has shown that the grain aphid carrying the mutation conferring partial resistance to pyrethroids does not vector the virus more efficiently. However, our work has also shown that the behaviour of our grain aphids is affected when carrying the virus, with greater mobility favouring further virus transmission.
In the below video, Louise McNamara, Jack Perry and Maximilian Schughart provide an insight into their research work and what they will discuss at the upcoming Crops and Cover Crops Cultivations event, which takes place in Teagasc Oak Park on Wednesday, June 21st.
By combining data from the extensive monitoring programme, with research into virus transmission, we aim to enhance our understanding of BYDV risk and spread. Our next challenge is to understand how these different virus strains impact yield and determine the role that new tolerant cultivars can play in Ireland. This will improve our ability to advise on spray decisions for control of aphids and BYDV in the future.
Louise McNamara and her team will present key findings of their research at the Crops and Cover Crop Cultivations Open Day on Wednesday, June 21st. For more information on this open day, click here.