Origins of Six Species of Butterflies Migrating through Northeastern Mexico: New Insights from Stable Isotope (δ2H) Analyses and a Call for Documenting Butterfly Migrations

Abstract

Determining migratory connectivity within and among diverse taxa is crucial to their conservation. Insect migrations involve millions of individuals and are often spectacular. However, in general, virtually nothing is known about their structure. With anthropogenically induced global change, we risk losing most of these migrations before they are even described. We used stable hydrogen isotope (δ2H) measurements of wings of seven species of butterflies (Libytheana carinenta, Danaus gilippus, Phoebis sennae, Asterocampa leilia, Euptoieta claudia, Euptoieta hegesia, and Zerene cesonia) salvaged as roadkill when migrating in fall through a narrow bottleneck in northeast Mexico. These data were used to depict the probabilistic origins in North America of six species, excluding the largely local E. hegesia. We determined evidence for long-distance migration in four species (L. carinenta, E. claudia, D. glippus, Z. cesonia) and present evidence for panmixia (Z. cesonia), chain (Libytheana carinenta), and leapfrog (Danaus gilippus) migrations in three species. Our investigation underlines the utility of the stable isotope approach to quickly establish migratory origins and connectivity in butterflies and other insect taxa, especially if they can be sampled at migratory bottlenecks. We make the case for a concerted effort to atlas butterfly migrations using the stable isotope approach.

Do Nearctic hover flies (Diptera: Syrphidae) engage in long‐distance migration? An assessment of evidence and mechanisms

“…As insects grow and develop, δ 2 H values from the hydrosphere are reflected in their tissues. These are then permanently fixed in certain adult tissues, thereby revealing signatures specific to their larval habitat and enabling researchers to determine migratory status and potential natal origins of individual insects (Brattström et al, 2010; Flockhart et al, 2017; Hobson, 1999; Hobson, Kusack, & Mora‐Alvarez, 2021; Hobson & Wassenaar, 2019; Wassenaar et al, 1998). Isotope techniques are powerful tools for disentangling whether insects migrate and how far they fly, but typically do not provide information on the mechanisms of migration.…”

An insect isoscape of UK and Ireland

“…16,17 In addition, emergent Red Admiral butterflies (Vanessa atalanta) and Silver Y moths (Autographa gamma) from several locations in western/ southern Europe have been discriminated using δ 2 H values, 18 and six species of North American butterfly were also provenanced using δ 2 H values. 19 To assign location based on stable isotope ratios, one requires a spatial landscape of environmental isotopic variation or "isoscape". 20 There are essentially two approaches to this: (i) for hydrogen and oxygen isotopes, using precipitation isoscapes derived from the Global Network of Isotopes in Precipitation (GNIP) 21,22 and a linear transfer function which relates the stable isotope ratio of tissues synthesised at known locations to that of precipitation 8 ; and (ii) a direct approach using the isotope ratio of a non-migratory analogue.…”

“…Examples are: Monarch butterflies (Danaus plexippus 2 H,  18 O and  13 C values) [9][10][11][12] , Painted Lady butterflies (Vanessa cardui,  2 H values) 13,14 , Common Green Darner dragonflies (Anax junius,  2 H values) 15 and Globe Skimmer dragonflies (Pantala flavescens,  2 H values) 16,17 . In addition, emergent Red Admiral butterflies (Vanessa atalanta) and Silver Y moths (Autographa gamma) from several locations in western/southern Europe have been discriminated using  2 H values 18 , and six species of North American butterfly were also provenanced using  2 H values 19 .…”

Using stable isotopes (δ2H, δ13C) to identify natal origins and larval host plant use by western bean cutworm, Striacosta albicosta (Lepidoptera: Noctuidae) captured in southern Ontario

“…From a more theoretical perspective, delineating migratory connectivity between life-history stages in migratory insects informs our knowledge of the evolution of migration and more proximate mechanisms that control it. The recent refinement of techniques using endogenous markers, such as naturally occurring abundance of stable isotopes (Hobson & Wassenaar, 2019), has provided a relatively new tool that could allow researchers to not only gain insight into composition of larval diets (reviewed by Quinby et al, 2020) but also geographic origins of immigrants (Hobson et al, 2018(Hobson et al, , 2021Hobson & Wassenaar, 2019).…”