Investigation of resistance levels of house fly (Musca domestica L.) populations against clothianidin and dinotefuran insecticides in Antalya

The housefly (Musca domestica L.) is a synanthropic species that can easily adapt to various environmental conditions and poses significant risks to both human and animal health. This species acts as a mechanical vector for various pathogenic microorganisms and causes stress in livestock, leading to reductions in milk and meat production. Therefore, the use of effective insecticides in housefly control is of great importance. Neonicotinoid-class insecticides are widely used due to their high toxicity and rapid mode of action; however, the development of resistance to these compounds and their adverse effects on non-target organisms have been increasingly studied on a global scale. In this context, monitoring resistance levels to neonicotinoids in housefly populations has become essential. The aim of this thesis is to determine the resistance levels of M. domestica populations collected from the districts of Aksu, Alanya, Döşemealtı, Kemer, Kepez, Konyaaltı, Korkuteli, Manavgat, and Serik in Antalya Province against two neonicotinoid active ingredients: clothianidin and dinotefuran. The flies were collected from livestock farms using baited traps and reared in 20×20×20 cm ventilated cages under laboratory conditions. Resistance tests were conducted on third-generation (F3) individuals using the World Health Organization (WHO)-recommended glass jar residual surface method. All assays were carried out under controlled conditions of 24 ± 2 °C temperature, 60 ± 5% relative humidity, and a 12:12 hour light-dark photoperiod. The flies were exposed to clothianidin and dinotefuran for one hour, during which knockdown (KD) rates were recorded at five-minute intervals. After exposure, flies were transferred to insecticide-free jars, and mortality rates were recorded after 24 hours. KD times and mortality rates were analyzed using the SPSS statistical software, and LD₅₀ and LD₉₀ values were calculated via probit analysis. Resistance ratios (RR) were determined by dividing the LD₅₀ and LD₉₀ values of field populations by those of a susceptible reference population. Additionally, the LD₉₀ values of field populations were compared to the standard dose (0.25 g ai/m²) recommended by the Turkish Ministry of Health for further evaluation. According to the results of this study, resistance to both clothianidin and dinotefuran was detected in all tested populations. The resistance ratios for clothianidin were found to be higher than those for dinotefuran. These findings suggest that the continuous and exclusive use of neonicotinoids for housefly control is not sustainable, and that integrated pest management (IPM) strategies should be implemented to prevent or delay the development of resistance.