Publication Database

Artificial feeding of the hard tick Ixodes ricinus (2024)

Art

Hochschulschrift

Autor

Militzer, Nina (WE 13)

Quelle

Berlin, 2024 — VII, 135 Seiten

Sprache

Englisch

Verweise

URL (Volltext): https://refubium.fu-berlin.de/handle/fub188/43678

Kontakt

Institut für Parasitologie und Tropenveterinärmedizin

Robert-von-Ostertag-Str. 7-13
14163 Berlin
+49 30 838 62310
parasitologie@vetmed.fu-berlin.de

Abstract / Zusammenfassung

The artificial tick feeding systems (ATFS) offer a promising alternative to animal experiments. They can be used for studies of tick biology and physiology, for experiments investigating the tick microbiome, novel tick control strategies and the tick-(microbiome)-pathogen interface as well as to facilitate tick rearing. At a time where globalization and global warming is affecting the prevalence, distribution and host encounters of ticks, research regarding ticks and tick-borne diseases is particularly important. The junior research group “Tick-borne Zoonoses” was founded to develop innovative and practical approaches to studying the vector biology of Europe’s most common hard tick species, Ixodes ricinus. This PhD project specifically focused on the use of ATFS for feeding of I. ricinus ticks. Chapter 1 provides an introduction to the biology and relevance of I. ricinus in Europe, as well as delving into an explanation of the different components and applications of ATFS. In Chapter 2, results from our first study are used to compare and contrast tick feeding of multiple consecutive life stages of I. ricinus between the in vitro feeding by ATFS and in vivo on live cattle. Findings showed that artificially fed ticks were generally inferior to ticks fed on live cattle and all life stages showed significantly longer feeding durations. However, in larvae, higher engorgement and molting proportions indicated that the ATFS was more effective than in vivo feeding. Further, the feeding and fecundity parameters for F1 adults improved after B vitamin supplementation and a water bath system. The prolonged feeding durations commonly observed in the ATFS are associated with an increased risk of contamination, even if the blood meal is supplemented with the antibiotic gentamicin. However, both bacterial contamination and antibiotic treatment have been linked to negative effects on feeding success. To further investigate the effects of using gentamicin in the ATFS on the tick microbiome, ticks were consecutively fed on cattle blood with and without gentamicin in an ATFS. A multimethod approach involving amplicon sequencing of 16S rRNA and further quantification of common bacteria using qPCR was used. Chapter 3 describes the results and compares the findings to ticks fed on live cattle. Despite facing challenges around the extraction and sequencing of DNA from individual ticks, we were able to show that in female ticks fed on live cattle the dominant symbiont was Candidatus Midichloria mitochondrii. In female ticks fed in the ATFS using a gentamicin-treated blood meal, the most abundant bacterium was Rickettsia helvetica. Hence, we were able to deduce that both fecundity and microbial composition are likely to be influenced by the ATFS. These findings should be taken into account for future studies using the ATFS.