DNA Damage Induced By High Temperature In Resistant And Susceptible Strains Of Plutella Xylostella L.

The single cell gel eletrophoresis,also called comet assay,was a sensitive,quick and cheap microscopic method to detect and quantitate DNA damage in eukaryotic cells.It had been used in different field,including genetic toxicology,environment toxicology,molecular epideiology and DNA damage and recovery in the past few years.Liamondback moth,which belongs to Lepidotera plutellidae,is one of the most important worldwide pests,with high insecticide resistance.Up to now,most study was in physiology and biochemistry field.Little study was known about the genetic and molecular base.This study aimed at using single cell gel eletrophoresis to know the connection between temperature and DNA damage of avermectins resistance and susceptible Plutella xylostella L.sperm,illuminated the connection between inheritance of resistance and temperature.The results might be a helpful tool for resistance detection.The survival of diamondback moth was strongly inhibited by high temperature. The death rate of resistant and susceptible strains at different temperature were obviously different,susceptible strains were higher temperature resistance to resistant strains(P＜0.05).After treating with 40℃for 48h and 72h,the death rate were 15.33%and 22.67%for male resistant strains,8.33%and 13%for male susceptible strains,31.33%and 73.33%for female resistant strain and 12.67%and 46.00%for female susceptible strains srespectively.DNA damage induced by temperature in avermectins resistant and susceptible Plutella xylostella L.sperms was studied using single cell gel electrophoresis.The results showed that the DNA had been damaged worse and worse with the treated temperature becongming higher at the constant time.And that the DNA had been damaged worse and worse with the treated time becongming longer at the fixed temperature.And avermectins resistant Plutella xylostella L.was damaged by temperature easier than susceptible Plutella xylostella L(P＜0.05).The study showed that the damage of the total DNA of Plutella xylostella L.also obey this disciplinarian. So the avermectins susceptible Plutella xylostella L.was more adaptive to the changes of environmental temperature in genetics.Separated DNAs were dealt with three temperature treatment at 30℃,35℃,40℃for 24h,48h,72h respectively,take 25℃as control.The length of cometic tail and damage rate of DNAs were taken as SCGE indices.Results showed that DNAs in control group were free of damage,static in electric field and manifested as a round fluorophoreu without any cometic tails.While other dealt DNAs were damaged to various degrees and demonstrated as cometic fluorophoreu in electric field after Ethidium bromide(EB)stain.Furthermore,with the incremental temperature damage rate and migration distance also enlarged accordingly.Therefore,it was concluded that DNA damage induced by high temperature in Plutella xylostella and the damage degree was related to certain temperature.This study also testified that SCGE can be used for Plutella xylostella sperm DNA damage detect.DNA damaged ofPlutella xylostella L.was detected by SCGE when growth at dfferent temperature for 24h,48h and 72h.The result showed that when gowth at 30℃DNA damaged of avermectins susceptible Plutella xylostella L.was 1%,0.5%and 1%respectively and of avermectins resistant Plutella xylostella L.was 0.5%,1%and 1.33%respectively.DNA damaged of avermectins susceptible Plutella xylostella L.was 4.0%,6.0%and 8.0%and of avermectins resistant Plutella xylostella L.was 5.0%,7.5%and 10.0%respectively when gowth at 35℃.DNA damaged of avermectins susceptible Plutella xylostella L.was 7.0%,9.0%and 11.0%and of avermectins resistant Plutella xylostella L.was 8.0%,10%and 13.0%respectively when gowth at 40℃.While those dealt DNAs were damaged to various degrees and demonstrated as cometic fluorophoreu in electric field after Ethidium bromide(EB) stain.Furthermore,with the incremental treatment time damage rate and migration distance also enlarge accordingly.Therefore,it was concluded that certain treatment temperature induce DNA damage in different time and the damage degree is related to time,which have been attested using SCGE.Temperature could inhibited the growth of Plutella xylostella.The result showed that with the incremental treatment time and temperature the pupate rate and pupae weight reduced and the pupate time enlarged accordingly,and Plutella xylostella becoming more and more susceptible to avermectins,such as treated with 40℃.