The green peach aphid is an economically important crop pest that is worth keeping a close eye on.
As one of the most insecticide-resistant insect species worldwide, we’ve been doing just that for quite some time. Recently in a collaborative study published in Insect Biochemistry and Molecular Biology, we have findings that, once again, demonstrate the adaptative potential of this species.
This research, supported through funding provided by the Grains Research and Development Corporation and Corteva Agriscience, has revealed significant levels of insecticide resistance to sulfoxaflor in the green peach aphid in Australia.
And notably, resistance persists after many months of culturing in the laboratory in the absence of insecticide exposure, demonstrating the heritable basis of this resistance.
These are important findings given sulfoxaflor is one the last remaining active ingredients in the grains industry that remains effective against the green peach aphid. With evolved resistance to many registered insecticides, the list of available chemical control options is quickly diminishing.
How’d we get here
The green peach aphid, Myzus persicae, is a global pest with an extremely broad host range of more than 400 different plants species. In Australia, they infest a variety of horticultural and broadacre crops including canola, lupins, field peas, capsicums, pepper, eggplant, cruciferous vegetables, and tomatoes.
In this study our researchers from Cesar Australia, together with The University of Exeter, The University of Melbourne and CSIRO, examined the sensitivity of green peach aphid populations from Western Australia to sulfoxaflor.
An important backstory here is that in 2018 the insecticide Transform® – containing the active ingredient sulfoxaflor – experienced control failures in canola fields following applications in the Esperance region of Western Australia.
However, it remained unclear the cause of these failures, whether due to poor application practices, the use of sulfoxaflor at rates below those recommended for green peach aphid, or because of resistance to the chemical.
New resistance findings
There were several questions this new research study set to answer. Firstly, to determine whether there were significant levels of resistance to sulfoxaflor present in field populations of aphids. And if so, whether this resistance was conferred by known mechanisms of resistance to neonicotinoids, that act on the same target-site as sulfoxaflor, or was due to novel mechanisms of resistance.
We found low, but significant, levels of resistance to sulfoxaflor across multiple independent bioassay experiments. And somewhat surprisingly, we identified two novel mechanisms – the overexpression of a P450 gene and a UDP-glucuronosyltransferase gene – conferring resistance to this compound.
This study demonstrates the importance of continued resistance monitoring of green peach aphid populations in Australia and elsewhere, and further highlights the need to implement long-term resistance management strategies in the field.
Find more information about Resistance Management Strategy for the Green Peach Aphid in Australia Grains via the GRDC website.
Technical input into this study was provided by James Maino, Siobhan de Little, Evatt Chirgwin, Andrew Weeks, Lisa Kirkland and Samantha Ward (Cesar Australia) and Victoria Mallott, Emma Bass and Jo Mackisack (University of Exeter).
We thank Ben Congdon, Emma Clarke and Alice Butler for assistance with aphid collections. This study was supported through funding provided by the Grains Research and Development Corporation and Corteva Agriscience.
The project also received funding from the European Research Council (ERC) and the European Union’s Horizon 2020 research and innovation programme (grant agreement n◦ 646625-P450RESIST and 773902–SUPERPEST).