Objective To measure the electrophysiological response of the Haller's organ of starving adult female Haemaphysalis longicornis ticks to several odor volatiles,and to provide a basis for further research on the host selection mechanism of ticks. Methods Electroantennogram with glass electrodes was used to measure the electroantennography (EAG) values of the Haller's organ of adult female H.longicornis ticks to glacial acetic acid,ammonia,and the blood,fecal,and fur extracts of Kunming mice,New Zealand rabbits,and sheep after 1 or 4 months of starvation,and the differences in data were analyzed for t test and analysis of variance using SPSS 22.0 software. Results Except for a relatively low EAG response value (0.000 mV) to glacial acetic acid with a concentration of 0.10 μl/ml,the Haller's organ of starving adult female H.longicornis showed varying degrees of electrophysiological reactions to glacial acetic acid and ammonia at concentrations of 1.00,10.00,and 100.00 μl/ml,and the degree of electrophysiological reactions increased with the increasing concentrations;The EAG values at different concentrations of glacial acetic acid and ammonia of Haller's organ of ticks in 1 month of starvation were higher than those of ticks in 4 months of starvation,but only EAG values at 1.00,10.00,and 100.00 μl/ml of glacial acetic acid,and 1.00 and 100.00 μl/ml of ammonia were significantly different between ticks with different times of starvation (all P<0.05).The ticks with starvation for 1 and 4 months showed the highest EAG response value to 100 μl/ml ammonia,i.e.,(2.729±0.129) mV and (2.239±0.285) mV,respectively,and the EAG response values to each concentration of ammonia were significantly higher than those to each concentration of glacial acetic acid (all P<0.05).The H.longicornis ticks after starvation for 1 month had similar EAG response values to the blood of Kunming mice,New Zealand rabbits,and sheep ( F=0.002, P=0.998),and as for the three kinds of animals,the ticks had relatively high EAG response values to the fecal and fur extracts of sheep,i.e.,(0.758±0.070) mV and (0.914±0.150) mV,respectively,which were significantly higher than the EAG response values to the fecal and fur extracts of the other two kinds of animals (fecal extract: F=11.587, P=0.001;fur extract: F=14.237, P<0.001). Conclusion At the same concentration,The Haller's organs of the adult female ticks of H.longicornis are more sensitive to ammonia than to glacial acetic acid,and the ticks after starvation for 1 month have stronger EAG response to ammonia and glacial acetic acid than those after starvation for 4 months.The EAG response of ticks to the fecal and fur extracts of sheep are stronger than those to the fecal and fur extracts of Kunming mice and New Zealand rabbits.