Screening Deltamethrine Resistance Molecular Markers In Culex Pipiens Pallens By AFLP

Mosquito is an important vector which transmits life-threatening vector-bornediseases. For a long period, chemical control works as a primary strategy to managethe mosquito-borne diseases. Excessive and continuous application of insecticideshas induced rapid development of insecticide-resistance in mosquitoes, which hasbecome the major obstacle for controlling the mosquito-borne diseases now.Identification and characterization of new insecticide resistance associated genes willcontribute to clarify the mechanism of insecticide resistance and find the strategy ofinsecticide resistance management.We developed two reciprocal F2intercross segregating populations from thecrosses of the insecticide-susceptible strain（S）and deltamethrin-resistant strain（R）in Cx. pipiens pallens. We compared the biological characteristics of F2intercrossprogeny among these4groups, like spawning rate, hatching rate, growth survival rateand resistant level. We qualified the487F2hybrids into8kinds of phenotype as10min,20min,30min,40min,50min,60min and after24h recovery dead or aliveaccording to WHO adult bioassay. Their survival was analyzed in the two groups.Based on the strategy of Bulk Segregate analysis (BSA), two gene pools wasrespectively constructed according to the extreme highest and lowest resistance todeltamethrine. A total of136primer combinations was tested on the gene pools toobtain the special AFLP markers tightly linked to high or low resistance todeltamethrine. Then we identified the frequency of these AFLP markers in the highand low resistance groups of F2populations.We developed two reciprocal F2intercross segregating populations from the crosses of S-strain and R-strain. It was observed that the resistant level of the hybridswas between their parents’, and the resistant level of the hybrids fromdeltamethrin-resistant female parent is higher than that of the another.We qualified the487F2hybrids into8kinds of phenotype as10min,20min,30min,40min,50min,60min and after24h recovery dead or alive according to WHOadult bioassay. Their survivals analysis and survival curve demonstrate that thesurvival rate of the hybrids from deltamethrin-resistant female parent is higher thanthat of the another, and grouping is the only factor.These results indicate that the deltamethrine resistant genes may link to sexchromosomes, and female parents may provide more resistance related genes.Based on the strategy of Bulk Segregate analysis (BSA), two gene pools wasrespectively constructed according to the extreme highest and lowest resistance todeltamethrine. A total of136primer combinations was tested on the gene pools toobtain the special AFLP markers tightly linked to high or low resistant todeltamethrine. Among the136AFLP primer combinations,29primer combinationsproduced polymorphic fragments with clear dominance inheritance patterns andreproducibility. These AFLP markers are linked to resistance related genes, and mayexist those genes around them.We identified the frequency of these AFLP markers in the high and lowresistance groups of F2populations. Among the AFLP R markers, the highestfrequencies markers are L1A29.153、L1A31.135、L1A31.143, and among the AFLPS markers, L1A25.70、L1A40.80have the highest frequencies. The frequencies ofthese markers are above60%in both of the F2populations.To sum up, we developed two reciprocal F2intercross segregating populationsfrom the crosses of S-strain and R-strain and obtain the special AFLP markers tightlylinked to high or low resistance to deltamethrine. Our study laid the groundwork for the identification of genetic polymorphism and genetic mapping of resistance genes.