First determination of diagnostic doses of the pesticide-sensitive strain of Haemaphysalis longicornis in China

Abstract Owing to the lack of research on pesticide-sensitive strains of Chinese Haemaphysalis longicornis, monitoring the resistance status of H. longicornis field populations is impossible, thus posing a risk to the control of drug resistance. For this purpose, the diagnostic doses (DDs) of 8 neurotoxic chemical acaricides in the Chinese pesticide-sensitive strain H. longicornis were detected via the larval packet test recommended by the Food and Agriculture Organization of the United Nations. The DDs were 0.080% w/v for cyhalothrin, 0.526%w/v for cypermethrin, 0.064% w/v for deltamethrin, 0.164%w/v for diazinon, 1.675%w/v for dichloro-diphenyl-trichloroethane (DDT), 0.880%w/v for ivermectin, 0.242%w/v for amitraz and 0.036%w/v for fipronil. This work represents the first record of a standard sensitive strain of Chinese H. longicornis. The obtained median lethal concentration (LC50) and DD values can be used as reference data in field populations for the detection of resistance in H. longicornis in different regions of China. These results can be used to evaluate the effectiveness of neurotoxic chemical pesticides on the market, optimize the usage strategy of pesticides, and provide a theoretical basis for improving the monitoring system of drug resistance. Additionally, we provide new genomic data for this species of tick, which allows for the development of a new method to screen for mutations associated with pesticide resistance, especially pyrethroids.