Neonicotinoid and pyrethroid target-site resistance in Italian populations of the green peach aphid (Myzus persicae).

Myzus persicae is a key pest of many crops, controlled mainly by chemical treatments. Till now neonicotinoids have been an important component of control strategies, but monitoring programmes in Southern Europe have recently shown the widespread presence of resistant populations, posing a serious threat to their long-term efficacy. This work describes the current Italian status of the main target-site mutations associated to neonicotinoid and pyrethroid insecticide resistance. R81T in the nicotinic receptor is very common in aphids from Italian specialised peach-growing areas, but it is also present in samples collected from herbaceous crops, underlying that resistant aphids, moving to secondary hosts, can affect any neonicotinoid-based management strategies. L1014F (kdr) and M918T (s-kdr) in the voltage sodium channel are present in almost all the populations collected, confirming the compromised effectiveness of this insecticide class for the control of this pest. The recently described mutation (M918L) in the s-kdr locus is present with two alternative polymorphisms (a/t or a/c) and it has been found in various genotype combinations with other target-site mutations. Our data describe a worrying situation that must be monitored, in order to avoid ineffective insecticide applications and to provide correct information to support coordinated control strategies regarding resistance management.