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

Abstract The frosted elfin Callophrys irus (Godart) (Lepidoptera: Lycaenidae), is an imperiled species endemic to fire-maintained habitats in eastern North America. C. 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 ºC and 30 ºC in addition to two moisture conditions of 5 and 15%. The null model outperformed other models, suggesting the effects of soil moisture and temperature on depth were negligible. The number of caterpillars that burrowed was similar to previous work with nine caterpillars that burrowed fully beneath the soil surface. If in-situ burrowing rates reflect our findings high mortality rates can be expected from fire. Thus, small, isolated populations may require artificial interventions. 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.