Thermotolerance and metabolic reserves of diapausing pupae of the western cherry fruit fly

The Western cherry fruit fly is a temperate fruit fly native to the Pacific Northwest. It is a pest of cultivated sweet cherries. This pest spends a majority of its life cycle as diapausing pupae but is was unknown what metabolic reserves this species utilizes to support metabolism. The levels of lipids, proteins, carbohydrates, and glycogen in pupae from 1 day after pupariation up though 20 weeks of cold exposure and 7 weeks of warm rearing conditions. Comparisons of metabolic reserves indicated that lipid reserves were the primary source of energy utilized by diapausing Western cherry fruit fly, and that protein and carbohydrate levels remained fairly stable throughout diapause. Glycogen levels fluctuated the most throughout the warm rearing conditions, indicating that lipid reserves were converted to glycogen to support metabolism during the latter stages of diapause in this species. Additional experiments using differential scanning calorimetry were used to determine the upper and lower limits of metabolism in diapausing pupae as well as the whole-body supercooling points. Early pupae exhibited lower supercooling points within 14 days of pupariation and retained this low level throughout diapause up to adult emergence. The determination of the lower and upper thermal limits indicated a high level of thermal tolerance in this species throughout diapause.