Investigation of knockdown resistance mutations in Ctenocephalides felis samples from the cat populations of Istanbul Province.

Effective control of the cat flea (Ctenocephalides felis) infestation is essential for human and animal health. To date, several ectoparasitic drugs, such as carbamates, neonicotinoids, phenylpyrazoles, and pyrethroids have been used to control flea infestations; however their widespread use has led to resistance, hampering treatment success. In this study, the resistance potential of C. felis collected from cats to fipronil (FIP), imidacloprid (IMI), flumethrin (FLU), and propoxur (PRO), which are the commonly used compounds for flea control, was investigated by molecular analyses. Bioassays encompassed exposure of adult cat fleas to FIP (2%), IMI (6%), FLU (0.1%), and PRO (0.1%)-impregnated papers using an insecticide susceptibility test kit according to the WHO protocol. Afterward, PCR was performed to identify mutations indicating resistance to FIP and FLU. Based on molecular analyses, mutations in the para gene of C. felis were identified as L1014F and T929V, indicating FLU resistance. Frequencies of T929V and L1014F mutations in fleas were 2.5% and 10%, respectively. On the other hand, two fleas that survived after eight hours of exposure to FIP lacked the A302S mutation, which was partially associated with FIP resistance. Even though our results revealed no resistance to FIP, IMI, and PRO in fleas collected from the study's cat population, the occurrence of FLU resistance due to mutations in the para gene of the fleas was demonstrated at the molecular level.