# The blood-sucking tick Ixodes hexagonus reveals dietary stable isotope signatures of mammalian hosts

## TL;DR

This study shows that blood-sucking ticks can retain dietary signatures of their mammalian hosts, offering a non-invasive way to study host diets.

## Contribution

The novel finding is that tick exoskeletons may reflect previous hosts, while whole ticks closely mirror current host dietary signatures.

## Key findings

- Tick exoskeleton isotopic signatures may represent previous hosts, while blood meals reflect recent hosts.
- Whole engorged ticks show δ15N values consistent with trophic enrichment from their current host.
- δ13C values in ticks are more variable, suggesting complex dietary or digestive influences.

## Abstract

Ticks are obligate haematophagous (‘blood-sucking’) ectoparasites that are capable of retaining host dietary traces post-moult, providing an opportunity to investigate parasite–host interactions and explore their potential as non-invasive subsampling techniques. However, research on the preservation of biochemical host signatures within whole engorged parasites remains limited. Here, we examine stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) across different tick tissues (exoskeleton vs. blood meal) and between whole ticks and one of their hosts, the European polecat Mustela putorius. Additionally, carbon and nitrogen weight percentages (wt%) are assessed to explore potential biochemical changes linked to blood meal digestion. Our findings showed that the isotopic composition of tick exoskeleton and blood meal differed significantly, with exoskeletons potentially reflecting a previous host. Whole engorged ticks showed a close δ15N relationship to their host, consistent with that of trophic enrichment, while the observed δ13C values were more variable. These findings enhance our understanding of how haematophagous parasites preserve host dietary signatures and, with further research, could support their use as a valuable alternative to invasive sampling methods, particularly when destructive sampling is not feasible.