Integrated pest management

Combatting insecticide resistance in the green peach aphid

Turnip yellows virus (TuYV) is not a present you want for your canola crop; however, the green peach aphid refuses to listen. When it comes to unwelcome guests, these tiny green guys really know how to ruin a party.

Not only do the aphids spread Turnip yellows virus (formerly known as Beet western yellows virus) as they feed, they are evolving resistance to most chemical control options available in grains.

With insecticide resistance in green peach aphid populations a growing and significant problem for the Australian grains industry, cesar is partnering up with the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Western Australian Department of Primary Industries and Regional Development (DPIRD) in a new four-year project to develop our understanding of this complex issue.

This new project, funded by the Grains Research and Development Corporation (GRDC) and in conjunction with ISK, BASF and Corteva, will focus on developing improved insecticide resistance surveillance, preparedness and virus management for the green peach aphid with an aim to increase adoption of integrated resistance management strategies for reducing Turnip yellows virus-incurred yield losses and to extend the life of existing chemical options.

The green peach aphid story

This project will build upon the research produced through a previous collaboration between cesar, CSIRO and DPIRD that ran from 2015-2019.

Resistance testing undertaken on aphid populations across Australia has demonstrated that the green peach aphid exhibits some level of insecticide resistance to five insecticide groups registered for use on this species in canola.

Research has shown that many green peach aphid populations are highly resistant to pyrethroids and carbamates, moderately resistant to organophosphates and that low-level resistance is developing to neonicotinoids.

Worryingly, reduced sensitivity to sulfoxaflor (Transform) was also detected in multiple Western Australian populations in the Esperance region. Sulfoxaflor had previously been the only registered active for use by the grains industry that remained fully effective against green peach aphid. If resistance to sulfoxaflor was to spread to other green peach aphid populations, it would represent a substantial threat for growers’ ability to control this pest effectively.

The findings from this past project demonstrated the importance of further developing our knowledge of these risks and appropriate management responses.

The Turnip yellows virus sneak attack

The green peach aphid tends to first appear in crops early in the season, moving in from host pastures or weeds. While the aphids attack a variety of broadacre, broadleaf pastures and horticultural crops, the major threat posed by the green peach aphid is rarely from direct feeding damage.

A more significant risk from feeding is the spread of plant viruses, notably Turnip yellows virus transmission in canola and other Brassicaceae crops.

Turnip yellows virus is not seed-borne and is carried by insect vectors from plant to plant, often hosted in weeds or volunteer plants through summer before being transmitted by feeding aphids to emerging crops.

Recent research as part of a GRDC-funded project has shown that most commercial canola varieties are highly susceptible to the Turnip yellows virus. It is therefore very important that Australian growers retain efficacy of key chemical controls by mitigating further insecticide resistance developments.

Crowd control measures

So, what can we do to combat these risks and minimise crop losses associated with insecticide resistance in green peach aphid? Well throughout this new project we will be looking to:

1)    develop a national insecticide resistance surveillance and testing program of green peach aphid populations;

2)    improve the industry’s preparedness for the future effects of insecticide resistance in green peach aphids by developing prediction modelling on the seasonal movement of aphid populations across the landscape;

3)    develop new methods for testing insecticide resistance to novel chemistries in green peach aphids;

4)    provide growers with updated resistance management information that reflects research on the regional and seasonal risk of green peach aphid and turnip yellows virus; and,

5)    develop informational material to support the adoption of effective resistance management strategies by growers and advisors that reflect the research findings.

Ultimately, by the end of the project in 2023, we hope for growers and advisors to have a better understanding of the risks of Turnip yellows virus transmission and improved tools for managing insecticide resistance in green peach aphids.

And in the meantime, over the next four years the project team will be providing the industry with updates on the key research outcomes and developing tools for improved management.  

Keep a lookout – there will be more to come!

Cover image: Photo by Julia Severi, Cesar Australia

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