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Unlabelled: Climate change is set to become one of the leading causes of biodiversity loss worldwide, with extreme weather events projected to increase in frequency. Ectothermic animals such as insects are at particular risk, especially when they are isolated and unable to move through the landscape to track suitable climate. To protect such taxa, it is important to understand how they are impacted by extreme weather events and whether management could provide effective microclimate refuges.

Day-flying lepidoptera larvae have a poorer ability to thermoregulate than adults.

Changes to ambient temperatures under climate change may detrimentally impact small ectotherms that rely on their environment for thermoregulation; however, there is currently a limited understanding of insect larval thermoregulation. As holometabolous insects, Lepidoptera differ in morphology, ecology and behaviour across the life cycle, and so it is likely that adults and larvae differ in their capacity to thermoregulate. In this study, we investigated the thermoregulatory capacity (buffering ability) of 14 species of day-flying Lepidoptera, whether this is influenced by body length or gregariousness, and whether it differs between adult and larval life stages.

Tropical butterflies use thermal buffering and thermal tolerance as alternative strategies to cope with temperature increase.

Climate change poses a severe threat to many taxa, with increased mean temperatures and frequency of extreme weather events predicted. Insects can respond to high temperatures using behaviour, such as angling their wings away from the sun or seeking cool local microclimates to thermoregulate or through physiological tolerance. In a butterfly community in Panama, we compared the ability of adult butterflies from 54 species to control their body temperature across a range of air temperatures (thermal buffering ability), as well as assessing the critical thermal maxima for a subset of 24 species.

Thermoregulatory ability and mechanism do not differ consistently between neotropical and temperate butterflies.

Climate change is a major threat to species worldwide, yet it remains uncertain whether tropical or temperate species are more vulnerable to changing temperatures. To further our understanding of this, we used a standardised field protocol to (1) study the buffering ability (ability to regulate body temperature relative to surrounding air temperature) of neotropical (Panama) and temperate (the United Kingdom, Czech Republic and Austria) butterflies at the assemblage and family level, (2) determine if any differences in buffering ability were driven by morphological characteristics and (3) used ecologically relevant temperature measurements to investigate how butterflies use microclimates and behaviour to thermoregulate. We hypothesised that temperate butterflies would be better at buffering than neotropical butterflies as temperate species naturally experience a wider range of temperatures than their tropical counterparts.

Oviposition behaviour and emergence through time of the small blue butterfly () in a nature reserve in Bedfordshire, UK.

Abstract: Climate change affects butterflies in many ways, influencing the timing of emergence and reproduction, habitat preferences, and behaviour. The small blue ( Fuessley, 1775) is highly specialised in its host plant requirements, feeding on the seeds of a single species, kidney vetch (), on which the larvae occur singly to avoid cannibalism. The butterfly is likely to be vulnerable to temperature-related changes in oviposition, adult emergence, and host plant flowering times, and is, therefore, a good model species for investigating climate change-related impacts.