Origin, selection, and spread of diamide insecticide resistance allele in field populations of diamondback moth in east and southeast Asia

Abstract

BACKGROUND: The investigation of molecular mechanisms and evolution of resistance to insecticides is an ongoing challenge, as researchers must provide guidance to manage the resistance to achieve sustainable production in agriculture. Predicting, monitoring, and managing insecticide resistance requires information on the origins, selection, and spread of resistance genes. The resistance of Plutella xylostella (L.) against diamide insecticides is becoming an increasingly severe problem in east and southeast Asia. In this study, the evolution of resistance was investigated using a resistance allele [ryanodine receptor (RyR); G4946E mutation] and its flanking regions, as well as mitochondrial cytochrome c oxidase subunit I (mtCOI). RESULTS: The sequences of the flanking region of the G4946E and mtCOI suggested that the G4946E mutation has a key role in resistance. Furthermore, the G4946E mutation has multiple origins, and congenic resistant mutations have spread across east and southeast Asia, despite substantial geographical barriers. In addition, the susceptibility of field populations partially recovered during winter, based on the observed decrease in the G4946E (resistant allele) frequency. Finally, the resistance level indexed by the frequency of the E4946 allele was significantly lower in non-overwintering regions than in overwintering regions. CONCLUSION: The information of the present study is useful to monitor resistance using molecular markers and to develop strategies to delay the evolution of diamide resistance.

Climate warming promotes pesticide resistance through expanding overwintering range of a global pest

“…Different pesticides and management practices across sites likely result in different levels of selection and/or resistance patterns that could have reduced our power to detect a general pattern across sites. Furthermore, migration may muddle resistance patterns due to the frequent gene exchange in non-overwintering areas that could either promote (the same variety of pesticide between emigrated area and immigrated area) 45 or reduce the resistance (the different variety of pesticides between emigrated area and immigrated area) 46 . These factors likely account for a good portion of the observed variation in pesticide resistance and could potentially reduce the effect of winter survival on the evolution of pesticide resistance.…”

Historical changes in the lethal effects of insecticides against the diamondback moth, Plutella xylostella (L.)

“…The decrease in susceptibility might be explained by two hypotheses: first, resistance evolved from the selection of insecticides within Japan; and second, the resistant individuals immigrated from continental Asia to Japan. 34,45 The rotation strategy underlies the recovery of susceptibility, which means that the resistance to one MoA insecticide declines when another MoA insecticide is being applied. 46 Resistance to these newer MoAs would continue to develop until it reaches an equilibrium between the selection pressure and the recovery of susceptibility, and such an equilibrium would depend on the fitness cost of the resistance to each MoA.…”

“…Nereistoxin analogues and organophosphates maintained longterm moderate effects, which might be owing to the fitness costs associated with resistance. The use of diamides also might be sustainable in the rotation strategy, unless they are used intensively, 34 because several authors have detected fitness costs associated with diamide resistance. 59,73 Several MoAs have become less effective in the 2010s, when the operation of the rotation programme began in Japan.…”

“…S1). 34 The data were categorized into four periods of P. xylostella collection before 1990, the 1990s, the 2000s and the 2010s. For the duplicate susceptibility data, only the data from the first publication were used.…”

“…In addition, the population of nonoverwintering regions is re-established annually by immigrants in the southern region, which might make a difference of susceptibility between regions of overwintering and non-overwintering. 34 The size of the fixed effects, except for the duration of the bioassay and relative concentration, was unstable in some cases. The effects might not be important to estimate differences among MoAs and periods when there is little information.…”