POST PUPARIATION COLD-STORAGE OF 3 SPECIES OF FLIES - INCREASING CHILLING TOLERANCE BY ACCLIMATION AND RECURRENT RECOVERY PERIODS

Three species of flies were examined for chilling tolerance front the end of the pupariation to the onset of adult eclosion for the purpose of determining applicability for cold storage. For the housefly, Musca domestica (Diptera, Muscidae), survival to eclosion was affected by d evelopmental stage/age, length of storage, and storage temperature. Ho useflies that were closest to having experienced pupariation or the on set of eclosion were the least cold tolerant. For flies stored at 7 or 10 degrees C, age groups placed directly into storage at 36-72 and 36 -48 h postpupariation, respectively, had significantly higher poststor age eclosion than younger or older age groups. Death was observed afte r only 2 or 3 days with the chilling intolerant groups while mid-aged groups survived 10-12 days under cold storage conditions. Damage could be reduced by giving the mid-aged groups chilled at 7 or 10 degrees C recurrent 2- or 3-h recovery periods every 4 days at 28 degrees C. Ex amination of O-2 consumption throughout the housefly pupal and pharate adult stages showed that the most chilling tolerant groups also had t he lowest metabolic activity. Combining a prestorage 17-h slow cooling acclimation interval with the recurrent recovery periods increased ec losion of adults 20% for the 12- to 24-h group after 21 days storage a t 7 degrees C. Two blowfly species, Lucilia cuprina and Lucilia serica ta (Diptera, Calliphoridae), survived 10 degrees C storage best when g iven a weekly 4-h recovery period. Survival at 90 days poststorage was nearly 50% for L. cuprina and 80% for L. sericata. Increasing surviva l under subambient temperatures for all three species appears to relat e to whether there is a stage of development which allows cold-induced lowering of metabolism that results in a dormant status best characte rized as hibernal quiescence. This study indicates that periodic warmi ng during cold storage increases survival by allowing a chilling intol erant stage to develop to a more tolerant stage and/or by eliminating accumulated toxic metabolites, (C) 1998 Academic Press.