Diamondback Moth Resistance To Three Insecticides Genetic Basis Of Research

The resistance management of Plutella xylostella(L.) that represents one of the extreme cases of insecticide resistance in arthropods is a hard and serious problem in the world. However, up to now, little is known about the genetic and molecular bases, which retards the resistance management and effective control. The mechanism of resistance is very complex which refers to the change of behavior, enzymes in metabolizability and insecticides' targets, and is different in different insecticides. Because most of the molecular biology methods applied aim at known or simplex object, how to improve on methodology so as to get more genetic markers even genes related to resistance has great importance to the research, monitoring and management of insecticide resistance.In this study, chromosome analysis, random amplified polymorphic DNA analysis and representational difference analysis have been conducted on susceptible strain and dimehypo-resistance, deltamethrin-resistance, cartap-resistance near isogenic strain. Followed are our main results:1.Chromosomal preparations were made from brain ganglia by usingNaCl-acetic Caraoy-air drying method on susceptible and insecticide resistance strain, which showed that 2n=30 and the chromosomes present cosh-like. No distinct difference occurred between susceptible and resistance strain.2.DNA from susceptible and four near isogenic strains were compared u sing optimized randomly amplified polymorphic DNA(RAPD) methodswith 35 p rimers. We got 9. 7 and 11 well-repeated special bands in the NILS of dimeh ypo-resistance. deltamethrin-resistance and cartap-resistance respectively with 16 primers which can be considered as genetic markers linked to susceptivity to d imehypo. deltamethrin and cartapin diamondback moth.3.Representational difference analysis(RDA) was applied to findmore diff erences between susceptible and the other three resistance strains. With suscepti ble strain as Driver and the other three as Tester respectively, subtractive hybridization and dynamic enrichment werecarried out and produced several different fragments finally. Through southern blot with partial probes we have got 2,2 and 3 special fragments in the NILS of dimehypo-resistance, deltmethrin-resista nee and cartap-resistance respectively.Taken together, compared with the susceptible strain, the resistance strai ns have no obvious changes in karyotype but have distinct difference in DNA level, which suggests that insecticide resistance is related to the changes hi gen omic DNA in diamondback moth.