Detection of resistance to some ectoparasitic products in fleas collected from cats in İstanbul

Cat flea (Ctenocephalides felis) poses a global threat to animal health and can cause significant health problems by infecting both animals and humans. In addition, it also poses significant risks to human and animal health by acting as a vector for bacterial, viral or parasitic pathogens. Over the years, ectoparasitic substances such as carbamates, neonicotinoids, phenylpyrazoles and synthetic pyrethroids have been widely used to control and treat flea infestations. However, the widespread use of these ectoparasitics has led to the development of resistance, potentially rendering treatments ineffective. Monitoring ectoparasitic resistance and understanding the underlying mechanisms is critical in developing strategies for resistance management and flea control. The aim of this study was to investigate the current status of resistance in fleas to fipronil, imidacloprid, flumetrin and propoxur, the active ingredients of the most commonly used pharmaceuticals in veterinary medicine for flea control. Fleas collected from cats in two shelters in Istanbul were first biologically analyzed and their resistance to these active ingredients was determined. The average mortality rates of fleas after 1 hour, 8 hours and 24 hours were 42.5%, 95%, 100% fo fipronil, 72.5%, 100%, 100% for imidacloprid, 35%, 72.5%, 87.5% for flumetrin, 47.5%, 100% and 100% for propoxur. DNA was isolated from 5 fleas that did not die in 24 hours in the biological analysis with flumethrin and 2 fleas that did not die in 8 hours in the analysis with fipronil. A PCR targeting the para gene was applied to identify the L1014F and T929V mutation in the samples to be investigated for flumethrin resistance. The frequency of T929V and L1014F mutations in fleas was 20% (5/1) and 100% (5/5), respectively. The presence of the A302S mutation indicating fipronil resistance was investigated at the molecular level and no A302S mutation was found in the 2 fleas that did not die after 8 hours. The data obtained as a result of biological analyses revealed that there was no resistance to imidacloprid, which is used in the field against fleas, and propoxur, which has been used for many years but has been banned for use. It was concluded that there was no resistance to fipronil, but the slight decrease in knockdown was not at the molecular level. Resistance to flumetrin was also demonstrated at the molecular level by the presence of mutations in the para gene. Keywords: Flea, Resistance, Ectoparasiticide, Bioassay, Mutation