The effect of soil moisture and ambient temperature on pupation depth for the imperiled Callophrys irus

• Published in: Journal of insect conservation Vol. 27; no. 5; pp. 805 - 811
• Main Authors: Jonas, Emma N., Ball, Nelson T., Meyer, Robert T.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.10.2023; Springer Nature B.V
• Subjects: Abiotic factors; Ambient temperature; Animal Ecology; Biodiversity; Biomedical and Life Sciences; Callophrys irus; Caterpillars; Conservation Biology/Ecology; Endemic species; Entomology; Incubators; Insects; Land management; Life Sciences; Moisture effects; Original Paper; Prescribed fire; Pupation; Refugia; Soil moisture; Soil surfaces; Soil temperature; Soil testing; Temperature; Pupae; Management; Lepidoptera; Fire; Burrowing
• ISSN: 1366-638X; 1572-9753
• DOI: 10.1007/s10841-023-00500-z

The frosted elfin ( Callophrys irus [Godart]; Lepidoptera: Lycaenidae), is an imperiled species endemic to fire-maintained habitats in eastern North America. Callophrys irus spends the majority of the year as pupae that may be vulnerable to fires that occur during this life stage. One way C. irus survives fire is to burrow and pupate under the soil, but this behavior is variable between individuals. We ran an ex-situ test on the impact of two abiotic factors on the pupation depth of C.irus (n=60): ambient temperature and soil moisture. We used two incubators at 18℃ and 30℃ in addition to two moisture conditions of 5% and 15%. The null model outperformed other models, suggesting the effects of tested soil moisture and temperature levels on depth were negligible. The number of caterpillars that burrowed was similar to previous work as nine caterpillars burrowed fully beneath the soil surface. Therefore, if in-situ burrowing rates reflect our findings high mortality rates can be expected from fire. Only two caterpillars out of 60 (~ 3%) burrowed at a level deep enough to survive the expected lethal temperatures of a typical prescribed fire in north Florida. Implications for insect conservation Our results support previous recommendations on the importance of refugia and population/habitat-specific rotational burn schedules to ensure the long-term persistence of the species. These data, along with previously published evidence, suggest that caterpillars in-situ may be unlikely to pupate at depths deep enough to protect themselves against fire. Thus, land managers protecting small, isolated populations should consider artificial interventions when planning to burn.