Target-site mutations (AChE and kdr), and PSMO activity in codling moth (Cydia pomonella (L.) (Lepidoptera: Tortricidae)) populations from Spain

Abstract

Codling moth,Cydia pomonella(L.) is a key pest of global importance that affects apple fruit production andwhose populations have developed resistance to insecticides in many apple production areas. In Spain, enhancedcytochrome P450 polysubstrate monooxygenase (PSMO) activity is the main mechanism involved in insecticidedetoxification by codling moth, although acetylcholinesterase (AChE) target site mutations have been describedin two populations. However, the extent ofAChEand knockdown resistance (kdr) mutations in Spain is unk-nown. To assess the actual occurrence ofAChEandkdrmutations concurrently with the frequency of moths withPSMO enhanced activity (R-PSMO), 32 Spanishfield populations from four apple-growing areas of Spain andtwo susceptible laboratory strains were evaluated. R-PSMO was significantly higher in 23 chemically treatedfield populations from Extremadura, Catalonia and Aragon, with proportions that varied between 25% and 90%,but no significant differences among strains and the non-chemically treated orchards (organic or abandoned)were observed. TheAChEmutation (F290 V) was detected in allfield populations from Catalonia (n = 21) and inthreefield populations from Aragon (n = 5), with resistant phenotype proportions varying from 34.2% to 97.5%and from 7.2% to 65% in Catalonia and Aragon, respectively. In addition, thekdrmutation (L1014F) wasdetected in twelve Catalonianfield populations, at rates of incidence ranging between 2.6% and 56.8%. Apositive correlation between R-PSMO andAChEmutation was found. The origin of the mutations and theirability to persist and spread infield populations with different management systems is discussed.