An insect isoscape of UK and Ireland

Abstract

The study of insect migration is problematic due to the small size of insects. Stable isotope analysis can be used to elucidate movement, either by geographic assignment of location of a species, or by simply distinguishing migrant from resident populations. There are few isoscapes of any kind in the UK/Ireland available for interrogation. Thus, I have measured stable isotope ratios (of H, C, N and S) of 299 individuals of the non-migratory Brimstone moth (Opisthograptis luteolata) collected from 93 locations around the UK and Ireland by citizen scientists.Methods: After removing lipids, stable isotope ratios were measured by continuous flow isotope ratio mass spectrometry, using either a conventional elemental analyser (C, N and S) or a high-temperature, thermal conversion elemental analyser in reductive mode.Results: Maps (isoscapes) were constructed that illustrate the stable isotope spatial distribution of this insect. These are the first isoscapes of H, C, N and S of biological samples covering both UK and Ireland. Conclusions:The insect isoscape patterns can be explained from what we know of moth diet, climate and geology. Sulfur isotopes may be of particular use for distinguishing individuals from areas of unique geology. Isoscape patterns may (with care) predict isotope compositions of other, herbivorous, non-aquatic, chitinous taxa. Such isoscapes, when extended beyond the UK and Ireland, would provide a useful tool to elucidate insect migration.

Geographic distribution of feather δ34S in Europe

“…Coastal regions being the most enriched in 34 S and the distance to coastline being a key covariate of the geographic distribution of δ 34 S is in line with our predictions and previous studies (Fry 2006, Zazzo et al 2011, Amrani et al 2013). In contrast, the inland parts of Europe showed only slight differences in δ 34 S values between the regions and the absence of a systematic spatial pattern thus contrasts with previous regional- and continental-scales assessments (Wadleigh and Blake 1999, Valenzuela et al 2011, Bataille et al 2021, Newton 2021; Brlík et al 2022a). Among the explanations for the absence of such systematic spatial patterns in Europe could be: (i) the complex geography of the European continent, (ii) the spatial clustering of human population with related distribution of fossil fuel combustion intensity, and (iii) the effect of variability in redox state of wetland soils that influences tissue δ 34 S isotopic compositions.…”

“…Geographic distributions of stable sulfur isotopes ( δ 34 S) in recent organic tissues have already been modelled for Great Britain, Tanzania, sub-Saharan Africa, and the conterminous USA (Valenzuela et al 2011, Kabalika et al 2020, Newton 2021, Brlík et al 2022a). Additionally, a recent study used archaeological remains to predict the geographic distribution of δ 34 S in Europe (Bataille et al 2021).…”

A hydrogen isoscape for tracing the migration of herbivorous lepidopterans across the Afro‐Palearctic range

“…precipitation δ 2 H isoscape. 40 This dataset is also the first to analyze δ 2 H wing values for tropical climate increasing the coverage of existing known-origin insect δ 2 H wing datasets from boreal and temperate regions including United Kingdom and Ireland, 30 Europe, 29 New Zealand and Australia, 32 China 31 and North America. 15,18 To date, the primary isoscape used to track migratory insects for the Afro-Palearctic range 16,68 was based on the known-origin dataset obtained from a few sampling sites in Europe.…”

“…27 To assess this relationship, the δ 2 H in the wings of a sample set of known-origin individuals is analyzed and compared using a transfer function, which relates the δ 2 H values in the wings to the corresponding local predicted δ 2 H values in precipitation. 15,18,[27][28][29][30][31][32] Mean annual precipitation isoscapes have been traditionally used when applying hydrogen isotopes in provenance studies. However, in certain situations, time-specific (monthly) precipitation isoscapes can offer advantages over multi-year mean isoscapes.…”

“…Additionally, the length of time for the larval stage often varies with latitude in resident insects, introducing further complexity and variability into the tissue isoscape. 30 In these cases, monthly isoscapes could help capture the short-term temporal variation of δ 2 H in precipitation occurring during the larval stages. 33 Multiple transfer functions have been developed between the δ 2 H in insect wings of known-origin individuals and δ 2 H isoscape of precipitation.…”