| The ixodid tick Haemaphysalis concinna is widely distributed in China, Russia, France and Germany as well as temperate Eurasia. It can transmit a greatvariety of pathogens, including Borrelia spirochetes, Russian-spring encephalitis, Rickettsiasibirica and Crimean-Congo hemorrhagic fever virus. Amblyomma americanum previously considered to be localized in the southeastern of the USA and Gulf Coast regions of Mexico. In recent years, A. americanum have rapidly increased in numbers and range and has now been reported as established in 32 states throughout the Southeast, South Central, and Midwest regions as well as along the eastern seaboard as far north as Maine. It can transmit a great variety of pathogens, including Rickettsia amblyommii and Francisella tularensis. A. americanum has emerged among the most important tick species in public health in the United States.The life cycle and occurrence of H. concinna were investigated under natural field conditions in Eerguna National Natural Reserve Area situated on the China-Russia border in Inner Mongolia, China. The whole life cycle of H. concinna was allowed to complete in the plot in a natural tick habitat. With Oryctolagus cuniculus domestica supplied as hosts, the seasonal occurrence and behaviors of H. concinna were also observed in the field plot which was chosen in a natural tick habitat. Results indicated that the durations of the life cycle from unfed adults to the next generation unfed adults of H. concinna ranged from 124 to 186 days(average 153.1 days). It is obviously different from data under laboratory conditions. The average periods of eggs incubation is 41.3 days(range from 39 to 57 days), which is the longest period among the four developmental stages. The number of eggs was positively correlated with the weight of engorged females(r = 0.8562, p < 0.001). The female reproductive efficiency index(REI) and reproductive fitness index(RFI) was 6.2 and 4.3, respectively. We also investigated the seasonal activity and abundance of all the three developmental stages of H. concinna. The results indicated that H. concinna ticks were found mainly in shrubs and grasslands. Adults were found between February and October with a major peak in June. Larvae were mainly observed from late April to late September and displayed an activity peak in late July. Nymphs were mainly observed from March to October and had a peak in early July. Adults and nymphs of H. concinna were found attached on sheep and the most favorite sites for attachment were head and ears. Larvae of H. concinna were found only on two rodent species, Apodemus peninsulae and Eutamias sibiricus.We successfully established the artificial membrane feeding method for Amblyomma americanum. Using this method, A. americanum attachment rate was 66.7-85.7%(average 80.4%). The ticks unsuccessful bites to the artificial membranes were dead after 5 or 6 days. The feeding period ranged from10 to 19 days(average 15 days). The average preoviposition and incubation periods are 10 days and 2 months, respectively. Males often change its attachment sites and mate with females after feeding. We also tested two chemical drugs Resultz and Tick Safe Release(Tick-SR) on A. americanum and detachment rate and mortality rate were obtained. Different doses of Resultz were used on the females of A. americanum which were on the artificial membrane. The mortality of A. americanum at four different time points(30 min, 60 min, 5 h and 24 h) were obtained. Different doses of Tick-SR were used on the females of A. americanum which were on the artificial membrane. The detachment rate of A. americanum at four different time points(30 sec, 5 min, 30 min and 60 min) were obtained. The activity of feeding of A. americanum, before and after treated by Resultz and Tick Safe Release, was recorded via electrophysiological technique. Two kinds of electrophysiological signal were obtained and named Spike 1 and Spike 2. Spike 1 was the electrical signal of salivary gland secretion activity of A. americanum and Spike 2 was the electrical signal of sucking activity of mouthparts. Spike 1 and Spike 2 shows obvious regularity. After treated with Resultz, the feeding activities was stopped. After treated with Tick-SR, physical activity signal of ticks enhanced obviously, until detached from artificial membrane.Eight essential oils were tested for repellent of the tick A. americanum. All the eight essential oils are come from Oregano, Clove, Vetiver, Sandalwood, Cinnamon, Cedarwood, Peppermint and Thyme. The results indicated that compared with deet, oregano is the most close to the effect of deet in all eight essential oils. 50% effective concentration(EC50) of oregano is 0.113 and 95% confidence interval(95%CI) is 0.09~0.14. But deet is 0.020 and 0.002~0.003. 95% confidence intervals of oregano and deet do not overlap, they are significant difference(P < 0.05); 50% effective concentration(EC50) of clove is 0.122, 95% confidence interval does not overlap with deet, they are significant difference(P < 0.05); The 95% confidence interval of clove are overlapping with oregano, they did not show significant difference(P > 0.05). The 50% effective concentration(EC50) of thyme, vetiver, sandalwood, cinnamon, cedarwood and peppermint are 0.132, 0.133, 0.147, 0.205, 0.224 and 0.297, respectively; The 95% confidence intervals are 0.11~0.16, 0.10~0.17, 0.10~0.20, 0.16~0.27, 0.17~0.31 and 0.23~0.39, respectively. Because of the 95% confidence interval(95% CI) of EC50 of them do not overlap, deet and oregano are significant difference(P < 0.05). |
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