Susceptibility of the Cowpea Aphid (Hemiptera: Aphididae) to Widely Used Insecticides in Australia

Discovery of insecticide resistance in field-collected populations of the aphid pest, Acyrthosiphon kondoi Shinji

BACKGROUND

The bluegreen aphid (Acyrthosiphon kondoi) is a worldwide pest of alfalfa, pulses, and other legume crops. An overreliance on insecticides to control A. kondoi has potentially placed populations under selection pressure favouring resistant phenotypes, but to date, there have been no documented cases of insecticide resistance. Recently, Australian growers began reporting that conventional insecticides were failing to adequately control A. kondoi populations, prompting this laboratory-based investigation into whether these populations have evolved resistance.

RESULTS

We discovered four A. kondoi populations with moderate resistance (10-40-fold) to three different insecticide groups: organophosphates, carbamates and pyrethroids. However, A. kondoi populations showed no resistance to the butenolide, flupyradifurone. We were unable to identify general metabolic mechanisms using synergist assays (cytochromes P450, glutathione S-transferases, or esterases), indicating that further detailed molecular investigations to characterise the putative resistance mechanism are needed.

CONCLUSION

Insecticide-resistant A. kondoi present an emerging challenge to Australian agriculture. Growers require new tools and updated strategies, including access to newer chemistries, to alleviate their reliance on the few insecticides currently registered against A. kondoi. The implications of insecticide resistant A. kondoi for future management, the potential mechanisms of resistance, and future research priorities are discussed. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.