The impact of elevated aestivation temperatures on the behaviour of Bogong Moths (Agrotis infusa)

Bogong moths are an iconic Australian insect that migrates annually in spring from low elevation locations in southern and eastern Australia to the Australian Alps where they aestivate during summer. As summer ends they make their return journey to the breeding grounds where they mate, lay eggs and die. Given the moth’s extreme behaviour in seeking out cool alpine habitat and with the knowledge that average temperatures at their aestivation sites are rising because of climate change, we assessed whether increased temperatures affect Bogong moth activity during aestivation. Our first hypothesis was that moth activity would be affected by temperature, and we found that moths were more active at higher temperatures, especially during the day, with near-constant activity at 15 °C at all times of day. Our second hypothesis was that moth mass would be different after aestivating at different temperatures for a week due to dehydration or consumption of body energy reserves. We found that moth wet mass loss increased with increasing temperature, but found no difference in dry mass among temperature treatments. Overall, our results suggest that Bogong moth activity will increase with increasing temperatures at their aestivation sites. The impact of warming on the success of individuals to complete their aestivation and journey back to their lowlands to breed should be investigated as a matter of priority to better understand the impact of changes in aestivation behaviour on population dynamics.