The in vitro feeding of hard ticks is a method that may be useful for studying different biological aspects of ticks and tick-borne diseases without the need for experimental animals. However, the development of standardized artificial feeding methods has been hampered by the complex feeding behaviour of hard ticks. The work described in this thesis therefore focused on the further optimization of artificial tick feeding methods using silicone membranes for the tick species Dermacentor reticulatus and Ixodes ricinus. Since the artificial feeding method requires regular laborious blood changes, the use of a semi-automated system (SAS) was also evaluated for feeding D. reticulatus and I. ricinus adults.
Various parameters were investigated in order to optimize the in vitro feeding of D. reticulatus adults, including different blood meal treatments (freezing, irradiation, addition of antibiotics), ambient conditions (increased CO2 concentrations) and phagostimulant supplements (glucose, adenosine triphosphate (ATP) and glutathione (GSH)). In addition, various substances that were previously reported to be attractive to other hard tick species were tested in behavioural assays for their capability to attract D. reticulatus. This included different concentrations of 2-nitrophenol, 2-salicylaldehyd, methyl salicylate, 2,6-dichlorophenol, uric acid, guanine hydrochloride and squalene, with animal hair extract as a positive control.
Although fungal growth occurred more frequent in feeding units of ticks fed on defrosted blood, the attachment rate, engorgement mass and fecundity of females fed on defrosted blood did not significantly differ from that of ticks fed on fresh blood. A reduction in the fecundity of female D. reticulatus ticks was observed when ticks were fed with gamma-irradiated blood or untreated blood compared to blood treated with gentamycin. Both the engorgement mass and fecundity increased when ticks were fed at a 5% CO2 level. A non-significant increase in the engorgement mass and engorgement rate of D. reticulatus was observed when blood was supplemented with 4 g glucose per liter compared to 2 g/l. The supplementation of blood with ATP and GSH had no significant effect on I. ricinus engorgement mass or fecundity. None of the tested substances was capable of attracting D. reticulatus adults in the behavioural assay.
Dermacentor reticulatus adults fed in the SAS obtained significantly higher engorgement masses and fertility rates compared to ticks fed in the conventional feeding system. In contrast, the engorgement rate and fecundity of SAS-fed I. ricinus were significantly reduced in comparison to ticks fed in the conventional system, which was likely to be caused by fungal infestation that could spread between feeding chambers in the SAS.
artificial tick feeding
500 Naturwissenschaften und Mathematik::590 Tiere (Zoologie)::595 Arthropoden (Gliederfüßer)
Optimization and Automation of Artificial Tick Feeding
Biologie, Chemie, Pharmazie