| Background:In recent years,mosquito-borne diseases such as dengue fever and Zika have often caused widespread outbreaks.With the long-term and extensive use of chemical insecticides,insecticide resistance has become a prominent problem affecting the prevention and control effect.Therefore,the research on the mechanism of insecticide resistance has become more urgent.Based on NMR untargeted metabolomics,our team found that trehalose content of deltamethrin resistant strains of Aedes albopictus was higher than that of sensitive strains in laboratory.Therefore,we hypothesized that trehalose accumulation and effective utilization could maintain or enhance the resistance to deltamethrin.of Aedes albopictus.Objective:Investigate the resistance to common insecticides in Aedes albopictus in Dongguan city,and investigate the trehalose content and related gene expression in Aedes albopictus at different resistance levels of deltamethrin.Methods:According to Test Methods of mosquito resistance to insecticides--Bioassay methods(GB/T 26347-2010),larvae dipping method on late third and early fourth instars was carried out to determine the half lethal concentrations(LC50)of Ae.albopictus,and the resistance ratios(RR)was calculated.Next,the level of resistance to deltamethrin of mosquitoes was determined by the Insecticide resistance bioassays recommended by WHO,so we obtained the populations of Aedes albopictus with different levels of deltamethrin resistance.The expression of trehalose related genes was detected by qRT-PCR and the trehalose content was detected simultaneously.Choose the population of the highest resistance level,separating and collecting the knockdown and survived ones after deltamethrin treatment,another part,then separating and collecting the dead and survived ones after 24h recovery,and use elisa test the content of trehalose,glucose and glycogen and the activity of trehalose transferase and trehalase,use qPCR to detect related expression of JH and 20E gene.Results:1.The RR of deltamethrin,temephos,DDT and bendiocarb of Aedes albopictus larvae in the four districts were 18.5-114,2.5-7.5,1.26-15.06 and 1.27-2.07 fold,respectively.2.With the Haizhu population as the experimental object,the mortality rate of adult Aedes albopictus to deltamethrin was 28.7%～85.1%.The higher the deltamethrin resistance,the higher the trehalose related gene expression level and trehalose content in Aedes albopictus were.The trehalose content was 1.34～2.83 times that of the laboratory sensitive strain.3.Under the action of deltamethrin,trehalose of Aedes albopictus(survived)increased by 117.7%,glucose decreased by 40%,TRET1 and TREA enzyme activity increased by 40.4%and 50.6%respectively,while trehalose related genes(TPS,TPP,TRET1,TREA)and 20E were inhibited,and the JH gene was 2.5 times more expressed than the control group.In the recovery stage,trehalose content increased by 85.6%,glucose decreased by 35.5%,and the expression of JH gene was no different from that of the control group.4.The activity of TRET1 and TREA enzyme in the survival group was 23%and 41.5%higher than that in the knockout group,and the expression of JH gene was 6.0 times higher.Conclusion:1.The resistance of Aedes albopictus to deltamethrin is generally higher in urban areas of Dongguan city.2.Deltamethrin-resistant Aedes albopictus has a high trehalose reserve.3.Under the pressure of deltamethrin,the increase of TRET1 and TREA enzyme activity may be related to the effective utilization of trehalose by deltamethrin-resistant Aedes albopictus.4.The JH may play an important role in the against of knockdown by deltamethrin in Aedes albopictus. |
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