Supporting data for "Distinct thermoregulatory strategies and challenges in subtropical butterflies and moths"

Temporal activity patterns expose animals to divergent thermal regimes and drive differences in their thermoregulation. In Lepidoptera (butterflies and moths), Clench (1966), in his influential work, discussed how diurnal butterflies and nocturnal moths may gain heat for activity. However, this characterization may not be applicable across all ecosystems. We investigated the thermoregulation of butterflies and moths in subtropical Hong Kong through the measurements of field body temperature (T_b), operative temperature (T_e), and set-point range (T_set; estimated as the preferred temperature). Subtropical diurnal insects have to lose heat in the hot season, while minimal thermoregulation was needed for nocturnal insects. Through microclimate selection and postural adjustments, both groups could regulate T_b towards their preferred T_set, which was not different between groups. Diurnal insects exhibited a heat threshold of 31.8 to 36.5°C, above which they buffered strongly against further increases in T_b, while nocturnal moths may have limited heat loss opportunities. Distinct thermoregulatory strategies may translate to distinct challenges for diurnal and nocturnal insects under climate change, further complicated by a diel asymmetry in warming trends and the changing availability of microclimates through large-scale habitat changes. A better understanding of thermoregulation in tropical insects is necessary for accurately characterizing their climate vulnerabilities.