Night versus day warming: asymmetrical impacts on predatory insects

Nights are warming faster than days under global climate change. Because plant activities, and their temperature sensitivities, vary diurnally, this asymmetric warming impacts plant responses to climate change. However, is not clear how insects, which also vary activities between night and day, are impacted by asymmetric warming. In this study we examined insect survival and emergence following different diurnal warming scenarios during winter for insects that overwinter at different life stages. We placed Praying Mantis eggs (Tenodera sinensis), Ladybeetle adults (Hippodamia convergens) and Darkling Beetle larvae (Tenebrio spp.) in mesocosms experiencing 2°C continuous warming or 4°C warming during night, day, or random twelve hour periods. We found that the mantids emerged earliest in the night warming treatment while the ladybeetles were more active during the continuous warming period. These findings suggest that asymmetric warming impacts multiple trophic levels and should be accounted for in predictions of ecological responses to climate change.