Rethinking bluegreen aphid control as insecticide resistance spreads

A study has revealed that insecticide resistance is now widespread among bluegreen aphids (BGA) in southern Australian legume crops, particularly alfalfa. This resistance renders broad-spectrum insecticides ineffective and raises concerns about further spread. Researchers collected BGA from pasture, seed and pulse crops across South Australia, Victoria, and southern New South Wales, finding resistant populations from the Eyre Peninsula to near Tamworth and in various parts of Victoria.

Resistance was more common in alfalfa but also detected in lentil crops in the Yorke Peninsula and Wimmera and Mallee regions. The study examined flupyradifurone, sulfoxaflor and flonicamid against resistant and susceptible BGA and found no evidence of resistance to these active ingredients, suggesting they could be viable alternative controls.

However, current registrations and permits for these products may vary between products and crops. Researchers also identified 132 parasitoid wasps of the species Aphidius ervi across South Australia, New South Wales and Victoria. This parasitoid wasp develops inside aphids and can help control BGA populations. The findings emphasize the importance of an integrated pest management approach, focusing on accurate identification of aphids, monitoring pest pressure and beneficial insects, and judicious use of insecticides only when necessary.

Growers should select products with appropriate modes of action, avoid repeated use of the same mode-of-action group, and consider the broader spray program to minimize selection pressure on BGA. Reporting control failures and adhering to Australian Pesticides and Veterinary Medicines Authority requirements will help manage resistance and maintain effective control options.