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Improving Aphid control through enhanced monitoring and diagnostics

Control of cereal aphids and BYDV virus is more challenging in recent years due to insecticide resistance and the recent loss of neonicotinoid seed treatments.The newly constructed Teagasc suction tower network improves farmer data and decision-making as Louise McNamara Crops Researcher outlines

The newly constructed Teagasc suction tower network coupled with advanced diagnostics aims to improve the information available, when making decisions about whether or not to apply an insecticide.



Why is this research important?

Currently no thresholds exist for controlling aphids and their associated virus in cereal fields. As low numbers of aphids are capable of spreading BYDV within a crop, the presence of aphids in a field is automatically considered a risk, even though the resistance status of the aphids and the presence of virus (i.e. viral load) in the aphids is unknown. Furthermore, virus levels vary from field-to-field and across seasons making it difficult to know when spray decisions are justified. These challenges may be causing overuse of insecticides, which in turn increases the risk of insecticide resistance developing further.

This research will allow us to:

  • understand the virus levels in migrating aphids
  • identify time periods when virus carrying aphids are most prominent,
  • associate aphid levels and virus status with the occurrence of BYDV in fields and resulting yields

Until now virus testing only allowed us to determine the presence/absence of BYDV; however, using new Droplet digital PCR (ddPCR) technology, we can quantify the level of virus in a sample. This  will allow us to gain evidence about the dynamics of virus spread by aphids, while also allowing us to determine the presence of BYDV virus in a plant, irrespective of whether there are visual symptoms or not.

What are you doing in this experiment?

Three 12.2 m suction towers have been constructed to date, in Oak Park, Ashtown and Cork. Information about migrating aphids from each tower is representative of a zone of approximately 80km diameter around the tower. Aphids are collected daily in the suction tower and identified in the laboratory, before undergoing molecular analysis to detect BYDV and/or confirm insecticide resistance status.

What have you observed/recorded to date?

Data from the Oak Park suction tower in 2020 found that the Bird Cherry-Oat Aphid R. padi was the most abundant migrating cereal aphid found and was present until the end of November. The grain aphid, S. avenae in comparison was only found until the end of August. Aphid flight strongly increased at mean temperatures above 15 °C and, as expected, strong winds and rain negatively affected aphid migration, as aphids cannot take off in unfavourable conditions.

In 2020, 22% of grain aphids recovered from the Oak Park suction tower tested positive for the gene mutation (kdr) conferring partial insecticide resistance to pyrethroids. This indicates that partially resistant aphids are still present in the population and capable of migrating large distances. The next research step is to incorporate BYDV testing of migratory aphids, and study the impact of different migrating aphids towards the spread of BYDV.

What does this research mean to a grower?

Through combining data from the Irish suction tower network with our advanced diagnostic tools, we aim to enhance our understanding of BYDV risk and spread. This will improve our ability to advise on spray decisions for control of aphids and BYDV in the future. Furthermore this platform allows us to monitor other insects of importance to growers in both tillage and horticulture sectors. 

Find more information on Teagasc Crops here