Green peach aphids with world-first resistance to popular active ingredient spirotetramat spark concern

Australia’s horticulture industry is on high alert after populations of green peach aphid were found with a world-first resistance to spirotetramat — an active ingredient in several insecticides — in Queensland vegetable crops.

The pest’s resistance to many chemical mode of action groups has been an ongoing management challenge for Australian farmers, with populations evolving resistance to synthetic pyrethroids, carbamates, organophosphates, neonicotinoids, sulfoxaflor.

Researchers recently found populations of green peach aphid with resistance to spirotetramat, which is the active ingredient in Movento 240 SC Insecticide, as well as several generic products containing the same active ingredient in crops at Burdekin in Queensland.

While the detection was limited to Burdekin, they believe the populations are likely to spread elsewhere.

Associate Professor Paul Umina, the director of Melbourne-based scientific research organisation Cesar Australia, led the research that led to the discovery through a collaborative effort with the University of Exeter.

The research was a co-investment by Bayer Crop Science and the Grains Research and Development Corporation.

“Resistance to spirotetramat has been confirmed in a small number of GPA populations collected from Queensland vegetable crops,” Professor Umina said.

“Importantly, this resistance has been shown to persist after multiple generations of culturing in the laboratory, demonstrating there is an underlying genetic basis.”

Spirotetramat, a Group 23 insecticide, is an important tool in GPA management in vegetable crops in Australia.

The research was a co-investment by Bayer Crop Science and the Grains Research and Development Corporation.

Spirotetramat resistance in GPA has not been found in any other country, despite this product being widely used to manage GPA in a range of crops around the world.

“Clearly, there is something that we are doing in Australia that is selecting for resistance in this species, which really should be looked at,” Professor Umina said.

Bayer Crop Science market development agronomist Troy Mulcahy recommended applying Movento early, before pest numbers build up.

“It should be applied as two sprays seven to 10 days apart to target a single generation of aphids for the most effective control,” he said.

Research has demonstrated that the correct adjuvant is essential to achieve high level pest control when using Movento.

Without the correct adjuvant, poor product performance will result.

“Thorough coverage is also critical, so spray booms need to be set up to deliver the chemical where the aphids are located and growers should pay attention to dust and honeydew on the leaf as these factors can all reduce product performance,” Mr Mulcahy said.

For a species like green peach aphid, which has a high propensity to evolve new resistances, this means only spraying insecticides when absolutely needed and rotating insecticides from different mode of action groups in those instances where multiple sprays are required in a single season.

Growers are urged to keep a close eye on their crops this year and to contact their local Bayer Crop Science territory manager if unsatisfactory aphid control is observed following the application of Movento.