Submitted to: Journal of Cryobiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/9/1998
Publication Date: N/A
Interpretive Summary: Three species of flies, Musca domestica, Lucilia cuprina and L. sericata, were examined for cold tolerance throughout the pupal and pre-eclosion adult stages for the purpose of determining cold storage applicability of these stages. This stage of development is often held at subambient temperatures for short-term storage and shipping purposes in sterile insect trelease programs used in suppression of dipteran livestock and fruit pests Further, adult survival is usually severely limited by cold storage of pre-eclosion stages extending past several days. This study shows that judicious selection of cold tolerant stages within this developmental time-frame coupled with recurrent in-storage warm recovery periods and a pre-storage cold acclimation will allow longer storage times along with increased survival of the insects tested. These manipulations can provide flexibility and economy for insectary and program managers when supplying insects for control purposes.
Technical Abstract: Three species of flies were examined for chilling tolerance for the purpose of determining cold storage capability. For the house fly (HF), survival to eclosion was affected by developmental stage/age, length of storage and temperature. Under continuous chilling, HFs that were closest to pupariation or eclosion were the least cold tolerant. For HFs stored at 7 or 10 deg C, groups placed directly into storage 36-72 and 36-48 hrs post pupariation, respectively, had higher post storage eclosion than younger or older groups. Chilling damage appeared to be cummulative and could be reduced by giving the chilled mid-aged groups recurrent 2 or 3 hr recovery periods every 3 or 4 days at 28 deg C. Survey of oxygen use throughout the HF pupal and pharate adult stages showed that the most chilling-tolerant groups also had the lowest metabolism. Oxygen use by younger and older age groups was 2-5 fold greater than mid-aged groups and these differences were eamplified up to 28-fold upon chilling. Combining a prestorage cold acclimation with recurrent recovery periods increased HF eclosion 20% for the 12-24 hr group after 21 days storage at 7 deg C. Two blow fly species, Lucilia cuprina (LC) and L. sericata (LS), survived 10 deg C storage best when given weekly 4 hr recovery periods. Survival at 90 days post storage was nearly 50% for LC and 75% for LS. Increasing survival under cold storage for all 3 species appears to relate to whether there is a stage which allows cold-induced lowering of metabolism to a dormant status known as hibernal quiescence. This study also indicates that periodic warming during cold storage increases survival by allowing a chilling intolerant stage to develop to a more chilling tolerant stage and/or to eliminate accumulated toxic metabolites.