Assessing the risk of resistance to flonicamid and afidopyropen in green peach aphid (Hemiptera: Myzus persicae) via in-vivo selection

Insecticide resistance is an ever-growing problem affecting crop production and pest management strategies worldwide. One of the most damaging aphid pests worldwide, the green peach aphid, Myzus persicae (Sulzer), has evolved resistance to at least 80 different active ingredients from a large number of chemical groups. In Australia, M. persicae has evolved resistance to organophosphates, carbamates, synthetic pyrethroids, neonicotinoids, sulfoximines and tetronic and tetramic acid derivatives. Two chemical options that remain effective against M. persicae in Australia are the recently registered active ingredients flonicamid and afidopyropen. Here, we investigated the potential risk of Australian populations of M. persicae evolving resistance to flonicamid and afidopyropen by undertaking an in-vivo selection experiment. Despite applying strong selection pressure to multi-clonal M. persicae colonies over 30 generations, we did not detect any meaningful shifts in sensitivity to either flonicamid or afidopyropen. At the conclusion of the experiment, LC50 values for flonicamid from unselected and selected colonies overlapped closely with the population baseline sensitivity responses prior to selection and with each other. A similar result was observed for afidopyropen, with LC50 values from unselected and selected colonies overlapping at the conclusion of the experiment. These findings support the long-term use of flonicamid and afidopyropen against M. persicae, but do not necessarily mean resistance will not evolve in the future, particularly if field practitioners ignore resistance management programs and use these chemicals indiscriminately.