| Summary: | 碩士 === 國立中興大學 === 昆蟲學系所 === 106 === Diamondback moth, Plutella xylostella, is extremely harmful to cruciferous vegetable crops. Chemical insecticides or microbial agents were often applied to control them in the field. Due to the short generation of development, the insecticide resistance of diamondback moth evolves very rapidly. In addition to reduced penetration, resistance mechanism includes target site insensitive and metabolic resistance. In this experiment, the substitutions at acetylcholinesterase 1 (AChE1), A298S, G324A and F386V used to establish susceptible strain 96Cggt and resistance strain 96CMNNN in previous study were used for selection (96CMNNN), bioassay and mutation frequency AChE1 gene to investigate the relationship between resistance ratio and mutation frequency. Then we did the synergism assay to observe the resistance ratio change after treated with synergist. And picked up the candidate gene from the result of transcriptome data, and validated by real-time qPCR. The results showed that after selected 16 generations, the resistance ratio was over 100. Moreover, the resistance was over 400 at 40th generation and had 3892.6-fold cross resistance to chlorpyrifos. But there was no cross-resistance to other insecticides with different mechanism mode of action. The mevinphos resistance in 96CMNNN of DBM is inherited as an incomplete dominant trait governed by more than one genes. The resistance mechanism involved in the resistance ratio between 30 and 120 is associated with AChE1 A298S, G324A and F386F/V amino acid substitutions or G892T, G971C, T1156T/G (TCN haplotype) mutations. Other mechanism may participate in resistance ratio shown at TCN frequency were 0 or 100%. The bioassay with various synergists did not show the involvement of cytochrome P450 monooxygenases (CYPs), esterases, glutathione S-transferase, UDP-glucuronosyltransferase (UGTs) and aldehyde dehydrogenase in mevinphos resistance. However, the comparative transcriptome analysis of 96Cggt and 96CMNNN strains of DBM, and the verification of real-time qPCR have shown that CYP6 family protein 6, Phosphatase methylesterase, UGT 2B2-like, and Aldehyde dehydrogenase might participate in mevinphos resistance of DBM.
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