Exposure of cold-adapted Diamesa mendotae Muttkowski, 1915 (Diptera: Chironomidae) to short-term high temperature reduces longevity and reproduction

Abstract Climate change is increasing mean winter temperatures and the frequency of short-term high temperatures. Winter-emerging aquatic insects require an extended cold period to develop and may be negatively impacted by high winter air temperatures. Diamesa mendotae Muttkowski, 1915 is a cold-adapted, winter-emerging chironomid common in groundwater-dominated streams in Minnesota. Previous studies have found constant exposure to high air temperatures reduced adult D. mendotae survivorship, but not how short-term high temperature exposure may affect D. mendotae survivorship and reproduction. We found short-term exposure (24 or 48h) to 22 °C decreased adult D. mendotae longevity and reduced egg laying and larval hatch success, which may reduce future D. mendotae population sizes. Disruptions in D. mendotae and other cold-adapted insect populations may have broad ramifications for groundwater-fed stream ecosystems. Our study highlights the need for further research on cold-adapted insect survivorship after short-term winter temperature spikes to understand impacts of climate change beyond mean annual temperature increases.