Field survey of ryanodine receptor mutations (G4946E and I4790K) and their effects on biotic performance in the diamondback moth

BACKGROUND: Resistance to diamide insecticides in Lepidoptera is known to be caused primarily by amino acid changes on the ryanodine receptor (RyR). Recently, two new target site mutations, G4946V and I4790M, have emerged in populations of diamondback moth, Plutella xylostella, as well as in other lepidopteran species, and both mutations have been shown empirically to decrease diamide efficacy. Here, we quantify the impact of the I4790M mutation on diamide activation of the receptor, as compared to alterations at the G4946 locus.RESULTS: I4790M when introduced into P. xylostella RyR expressed in an insect-derived Sf9 cell line was found to mediate just a ten-fold reduction in chlorantraniliprole efficacy (compared to 104-and 146-fold reductions for the G4946E and G4946V variants, respectively), whilst in the field its presence is associated with a ≥150-fold reduction. I4790M-mediated resistance to flubendiamide was estimated to be >24-fold. When the entire coding sequence of P. xylostella RyR was integrated into Drosophila melanogaster, the I4790M variant conferred ~4.4-fold resistance to chlorantraniliprole and 22-fold resistance to flubendiamide in the 3rd instar larvae, confirming that it imparts only a moderate level of resistance to diamide insecticides. Although the I4790M substitution appears to bear no fitness costs in terms of the flies' reproductive capacity, when assessed in a noncompetitive environment, it does, however, have potentially major impacts on mobility at both the larval and adult stages.CONCLUSIONS: I4790M imparts only a moderate level of resistance to diamide insecticides and potentially confers significant fitness costs to the insect.

Section: I4790m-mediated Resistance May Have a Costmentioning

confidence: 99%

Diamide insecticide resistance in transgenic Drosophila and Sf9‐cells expressing a full‐length diamondback moth ryanodine receptor carrying an I4790M mutation

Richardson

Homem

Troczka

et al. 2021

“…These sodium channel mutations have been widely detected in DBM populations in Australia, China, Korea, Thailand and Japan. The mutations I4790K/M, G4946E, E1338D and Q4594L were identified in the ryanodine receptor (RyR), conferring high resistance to the chlorantraniliprole in DBM 57–60 . The glutamate‐gated chloride channel (GluCl) is present only in invertebrates and is the main target gene of abamectin.…”

Section: Methodsmentioning

confidence: 99%

“…The mutations I4790K/M, G4946E, E1338D and Q4594L were identified in the ryanodine receptor (RyR), conferring high resistance to the chlorantraniliprole in DBM. [57][58][59][60] The glutamate-gated chloride channel (GluCl) is present only in invertebrates and is the main target gene of abamectin. The A309V substitution at the N terminus of the third transmembrane helix (M3) of the GluCl of DBM was identified in the resistant strain.…”

Section: Target Resistance Mutationsmentioning

confidence: 99%

A comprehensive assessment of insecticide resistance mutations in source and immigrant populations of the diamondback moth Plutella xylostella (L.)

Shen

Cao

Chen

et al. 2022

BACKGROUND The diamondback moth (DBM) Plutella xylostella has developed resistance to almost all insecticides used to control it. Populations of DBM in temperate regions mainly migrate from annual breeding areas. However, the distribution pattern of insecticide resistance of DBM within the context of long‐distance migration remains unclear. RESULTS In this study, we examined the frequency of 14 resistance mutations for 52 populations of DBM collected in 2010, 2011, 2017 and 2018 across China using a high‐throughput KASP genotyping method. Mutations L1041F and T929I conferring pyrethroid resistance, and mutations G4946E and E1338D conferring chlorantraniliprole resistance were near fixation in most populations, whereas resistant alleles of F1020S, M918I, A309V and F1845Y were uncommon or absent in most populations. Resistance allele frequencies were relatively stable among different years, although the frequency of two mutations decreased. Principal component analysis based on resistant allele frequencies separated a southern population as an outlier, whereas the immigrants clustered with other populations, congruent with the migration pattern of northern immigrants coming from the Sichuan area of southwestern China. Most resistant mutations deviated from Hardy–Weinberg equilibrium due to a lower than expected frequency of heterozygotes. The deviation index of heterozygosity for resistant alleles was significantly higher than the index obtained from single nucleotide polymorphisms across the genome. These findings suggest heterogeneous selection pressures on resistant mutations. CONCLUSION Our results provide a picture of resistant mutation patterns in DBM shaped by insecticide usage and migration of this pest, and highlight the widespread distribution of resistance alleles in DBM. © 2022 Society of Chemical Industry.

“…7,13 The another resistance-associated RyR amino acid substitution, I4790M, was first identified in a Chinese population of P. xylostella, 14 and then homologous point mutations to PxRyR I4790M were found in some diamide-resistant field populations of T. absoluta RyR (I4746M/T), 12 C. suppressalis (I4758M), 13 S. frugiperda (I4734M), 8 S. exigua (I4743M) 15 and Orius laevigatus (I4790M). 16 Recently, I4790K mutation was found to confer high levels of resistance to diamides in some field populations of P. xylostella from Japan, China and Australia, [17][18][19] and of S. frugiperda from Brazil. 20 Compared to intensive investigations on target-site resistance of diamides, the role and molecular mechanisms of metabolic resistance to the diamide insecticides in insects is less studied and not clearly understood.…”

Section: Introductionmentioning

confidence: 99%

The ryanodine receptor mutation I4728M confers moderate‐level resistance to diamide insecticides in Spodoptera litura

Mei

Zuo

et al. 2023

BackgroundThe common cutworm, Spodoptera litura (Fabricius), is one of the most widespread and destructive polyphagous pests in tropical and subtropical Asia. S. litura has evolved resistance to different insecticides, including diamide insecticides. Here, we identified a ryanodine receptor (RyR) mutation (I4728M) associated with target site resistance to diamides in a field‐collected population of S. litura. The contribution of this mutation to diamide resistance was investigated through establishing a near‐isogenic resistant strain of S. litura.ResultsThe ND21 population of S. litura, collected from Ningde, Fujian province of China in 2021, exhibited 130.6‐fold resistance to chlorantraniliprole compared to the susceptible NJ‐S strain. S. litura RyR mutation I4728M, corresponding to Plutella xylostella RyR I4790M, was identified in the ND21 population. SlRyR I4728M mutation of ND21 was introgressed into a susceptible background strain (NJ‐S) with marker‐assisted backcrossing. The introgressed strain named ND21‐R, which was homozygous for the mutant 4728M allele, shared about 94% of the genetic background with the NJ‐S strain. ND21‐R strain showed moderate levels of resistance to two anthranilic diamides (19.1‐fold to chlorantraniliprole, 19.7‐fold to cyantraniliprole) and the phthalic diamide flubendiamide (23.4‐fold). Genetic analysis showed that chlorantraniliprole resistance was autosomal, incompletely recessive and tightly linked with SlRyR I4728M mutation in the introgressed ND21‐R strain of S. litura.ConclusionIdentification of the I4728M mutation and its contribution to diamide resistance in S. litura will help develop allelic discrimination assays for resistance monitoring and guide resistance management practices for diamides in S. litura. © 2023 Society of Chemical Industry.