Supercooling points (SCP) of adult Diamesa mendotae Muttkowski, 1915 (Diptera: Chironomidae) were determined at 3, 5, 9, 12 and 17 days post-collection. Supercooling points were recorded using surface contact thermometry and a cooling rate of ca. 1°C min-1. Female SCPs averaged -22.81, -23.76, -23.85, -23.65, and -20.87°C on each date post-collection and did not differ significantly. Male SCPs were statistically similar and averaged -21.75, -23.53, -23.68, -23.66, and -22.92°C on each date post-collection. Paired comparisons of female/male SCPs on each date post-collection did not show significant differences over time. The overall mean SCP of D. mendotae (-23.05°C) is substantially lower than values of -5.3°C and -5.7°C published for adults and larvae of Belgica antarctica Jacobs 1900 collected at Palmer Station (Antarctica) and -14.2°C for larvae of Paraclunio alaskensis Coquillett 1900 collected at Vancouver Island, British Columbia. In addition, the SCP of this species appears to be lower than that of other winter-active insect species reported in the literature. Although no adults survived after the SCP was recorded, further studies are necessary to determine if D. mendotae is a freeze-intolerant insect. Nevertheless, our results suggest that a low SCP could be used as a mechanism to facilitate emergence and adult activity of this species during winter conditions.
Bibliographical noteFunding Information:
We would like to thank Peter Zwick, Henrique Paprocki and two anonymous reviewers for critical comments on an earlier version of this manuscript. This work was partially funded by the University of Minnesota Grant-In-Aid of Research and the Minnesota Agricultural Experiment Station.
Copyright 2008 Elsevier B.V., All rights reserved.
- Cold hardiness
- Diamesa mendotae
- Supercooling point
- Winter activity