TDK conference 2017

Deterring ticks - due to their parasitic and vector activity - is an important part of domestic animal health protection. Several natural substances come up, as a repellent; especially essential oils are the most common ones. However, evaluating the effect of a new repellent substance is a serious cost, if it is tested by animal experiments according to the regulations, moreover it requires a large amount of ticks. The animal welfare is important as well, so it would be great to substitute the animal testing by in vitro tests.

In our work, we have developed and tested a new in vitro test method. The repellent effect of two essential oils; citronellal and geraniol was compared to purified water as negative control and to N,N-diethyl-toluamide in 0.1% and 1% dilution as positive control. We also tested the concentration dependence of the two substances using 1%, 5% and 10% diluted aqueous emulsions using water as negative control. The test substances and controls were applied to gauze strips and placed in square form at the bottom of a cubic box of transparent plexiglass. We also carried out a control measurement using gauzes moistened only with water. The ticks were started from the centre at the same time, their motion was captured from a fixed position, and the parameters of the position and arrangement of ticks were used in the analysis. The data were analysed by R Commander, and Fisher's exact test was used to compare the differences between the distributions, all measurements were compared to the control, and the data of the concentration-dependence studies of the two substances were compared to each other as well. The uniform distribution of control run was tested by a chi-square test.

The concentration dependency of both the citronellal and the geraniol were significantly different in the distribution of ticks compared to both the control and each other. Among the measurements of comparing the strength, only the 1% concentration was significant. According to the results, the effect of citronellal is more dependent on the concentration than geraniol, which at low concentrations is quite deterrent for ticks, while the citronellal is less.

Compared to diethyl-toluamide, citronellal was less effective at low concentrations, but this was not observed in geraniol.

Overall, it can be said that the method is workable and is suitable for multiple comparisons.

Hereinafter, we would like to refine the new method to provide a precise, accurate, reliable

and well-performing preclinical test that can replace animal experiments.