What was it all about?

The green peach aphid is a major horticultural pest within Australia. It attacks a broad range of plants, including capsicum, eggplants, tomatoes, broccoli and lettuce. Insecticides are the main tool used to control this pest, but the aphid can rapidly acquire insecticide resistance. Within Australia, green peach aphid populations with resistance are increasingly common, posing issues both in the short and long term.

This project was undertaken to better understand resistance in green peach aphid populations across Australia, so that better insecticide resistance management strategies could be devised.

Researchers collected and cultured green peach aphid populations from 25 different locations across Queensland, Victoria, Tasmania, South Australia and Western Australia. They tested the aphids for resistance to four groups of insecticides in the lab.

In addition, the team developed testing methods for newer chemistries available for green peach aphid control. This provided baseline sensitivity data that will allow detection of any changes in resistance.

Since the cornerstone of any insecticide resistance management plan is to use different chemicals on a rotating basis, the team also compared the effectiveness of these newer chemistries.

Major findings from the work were

• Resistance to three major insecticide groups commonly used to control aphids in Australia (synthetic pyrethroids, carbamates and organophosphates) is widespread.
  
  
• Low levels of resistance to neonicotinoids were detected in a small number of aphid populations from Queensland, South Australia and Western Australia. This is the first time neonicotinoid resistance has been detected in Australia.
  
  
• Several resistant biotypes were found across horticultural regions, improving our understanding of the genetic make-up of aphid populations regionally and nationally, which suggests that the pest is able to move freely between crops, between production areas and even across states.
  
  
• Several chemical products from new chemical groups were found to be effective in controlling the pest.

The findings of this project, along with feedback from growers, advisors and agrichemical companies, were incorporated into a resistance management strategy focused on the Bundaberg vegetable growing region in Queensland.

While the management strategy has been optimised to help growers and advisors specifically in this area, with chemical and cultural management options based on local cropping practices, pest control, and environmental conditions, there are many elements of the strategy that are applicable nationally.

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Further details about the project and its findings are available in this Vegenotes fact sheet, produced by the levy-funded vegetable communications program