CONTROLLED-ATMOSPHERE EFFECTS ON BLUEBERRY MAGGOT AND LOWBUSH BLUEBERRY FRUIT

Larvae of the blueberry maggot (Rhagoletis mendax Curran) were raised on apples (Malus domestica Borkh. cv. Idared), and exposed larvae were treated 48 hours with CO2 concentrations ranging from 0% to 100% at O2 concentrations of 2%, 5%, or 20% (0% for the 100% CO2) at 5 or 21C. Blueberry maggot survival was reduced to 10% when the larvae were subjected to CO2 concentrations >45% at 21C. Fumigation was more effective at 21C than at 5C. Oxygen at 2% or 5% did not reduce larval survival when compared with treatments containing 20% O2. In a separate experiment, six commercial shipments, each consisting of four hundred eighty 0.5-liter containers of infested lowbush blueberries (Vaccinium angustifolium Ait.), were placed in a large riberglass tank and fumigated with 54% CO2 at 21C. The blueberries were sampled for quality and larval survival after 24 and 48 hours of CO2 treatment. After 48 hours, 9% of the blueberry maggots in infested blueberries survived fumigation with 54% CO2, while 68% of maggots survived in air. The quality of fumigated lowbush blueberries was not adversely affected by fumigation with 54% CO2 for up to 48 hours, as indicated by marketable berries, berry weight, split berries, shriveled berries, epicuticular wax (bloom), firmness, soluble solids and titratable acid concentrations, off-flavors, and skin browning.