Pyrethroid-Resistance and Presence of Two Knockdown Resistance (kdr) Mutations,F1534C and a Novel Mutation T1520I,in Indian Aedes aegypti

Control of aedes aegypti,the mosquito vector of dengue,chikungunya and yellow fever,is a challenging task. pyrethroid insecticides have emerged as a preferred choice for vector control but are threatened by the emergence of resistance. the present study reports a focus of pyrethroid resistance and presence of two kdr mutations—f1534c and a novel mutation t1520i,in ae. aegypti from delhi,india. insecticide susceptibility status of adult-female ae. aegypti against ddt (4%),deltamethrin (0.05%) and permethrin (0.75%) was determined using who's standard insecticide susceptibility kit,which revealed resistance to ddt,deltamethrin and permethrin with corrected mortalities of 35%,72% and 76% respectively. mosquitoes were screened for the presence of kdr mutations including those reported earlier (i1011v/m,v1016g/i,f1534c,d1794y and s989p),which revealed the presence of f1534c and a novel mutation t1520i. highly specific pcr-rflp assays were developed for genotyping of these two mutations. genotyping using allele specific pcr and new pcr-rflp assays revealed a high frequency of f1534c (0.41–0.79) and low frequency of novel mutation t1520i (0.13). the latter was observed to be tightly linked with f1534c and possibly serve as a compensatory mutation. a positive association of f1534c mutation with ddt and deltamethrin resistance in ae. aegypti was established. however,f1534c-kdr did not show significant protection against permethrin. the aedes aegypti population of delhi is resistant to ddt,deltamethrin and permethrin. two kdr mutations,f1534c and a novel mutation t1520i,were identified in this population. this is the first report of kdr mutations being present in the indian ae. aegypti population. highly specific pcr-rflp assays were developed for discrimination of alleles at both kdr loci. a positive association of f1534c mutation with ddt and deltamethrin resistance was confirmed. © 2015 kushwah et al.