Understanding bluegreen aphid resistance in the pasture seeds industry

  • 44 pages

  • Published: 5 Oct 2022

  • Author(s): Evatt Chirgwin, Joshua Thia, Katrina Copping, Paul Umina

  • ISBN: 978-1-76053-309-0

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Bluegreen aphid (BGA) is a pest of lucerne seed and other legume crops; the pest damages lucerne plants via direct damage due to feeding and indirect damage due to virus transfer. Traditionally, BGA has been controlled with several effective chemical control options and lucerne seed crop losses due to BGA damage have so far been minimal. However, the pest has potential to cause serious losses in the lucerne seed industry if chemical control is no longer effective.

In 2019, growers and advisors began reporting insecticides failing to achieve adequate control of BGA in lucerne seed crops to Cesar Australia, and these reports continued in subsequent years. Off the back of similar reports made to Lucerne Australia in 2021, this concern was raised with the AgriFutures Pasture Seeds Program to seek research and development support. As a result, an investment was made in this project to understand the scope of the issue and inform further research and development investments.

The project found that BGA populations collected from New South Wales (NSW) and South Australia (SA), where chemical control failure had occurred, have evolved resistance to organophosphates, carbamates and pyrethroids. It was also concluded that this resistance has a heritable basis, persisting in aphids that were cultured in the laboratory for multiple generations. These findings are consistent with growers’ reports of chemical control failure in the field.

The project also provides short-term (1-3 years) and long-term (more than three years) recommendations for how the lucerne seed industry might respond to the discovery of insecticide-resistant BGA. Short-term recommendations aim to provide growers and advisors with avenues to mitigate damage from insecticide-resistant BGA by using the tools and resources currently available; including chemical options, biocontrol, and cultural-control methods. Long-term recommendations identify the key gaps in scientific knowledge and tools available to growers, which will need to be addressed to develop effective long-term management strategies for BGA. Further investments will be made in this area of research to help the industry tackle BGA resistance.