Geographical variation in thermal acclimation responses to chill coma recovery time for Ceratitis capitata adults

Chill coma recovery time (CCRT) is considered an ecological relevant proxy of insect cold tolerance. We assessed CCRT and post-recovery fitness for Ceratitis capitata adults from six geographically isolated populations (Vienna, Austria; Thessaloniki, Northern Greece; Volos, Central Greece; Chios Island, North Aegean, Herakleio, Crete Island, Greece; South Arava, Israel). Adults (F₃-F₆ generation) were kept at 25^oC up to day five of age. Then, 20 males and 20 females from each population were acclimated at 10, 15, 20, or 30^oC for five consecutive days. Individuals who remained for the same period at 25^oC were used as control. For the CCRT assays, flies were placed in vials and maintained into slurry icy (0^oC) for 4h. Adults were transferred at 25^oC and immediately placed in a supine position. The recovery time was marked when each fly reached the upright position. Post-stress survival of adults from each treatment was recorded after 8 days following CCTR assays. The cold-acclimated adults had a shorter recovery time than the warm-acclimated adults. However, there were significant differences among populations in the strength of adult thermal plasticity for CCRT. The CCRT was significantly higher for the warm-acclimated flies from Thessaloniki and South Arava than the warm-acclimated adults from Volos and Chios. Females recovered faster than males. Post-stress survival of thermal acclimated adults was inversely related to chill coma recovery in Thessaloniki, Volos, and South Arava populations. Hence, CCRT seems to vary among geographically isolated medfly populations.