Larval survival and development of the peach fruit moth, Carposina sasakii (Lepidoptera: Carposinidae), in picked and unpicked apple fruits [Malus pumila var. domestica]

Larval survival and development of Carposina sasakii were examined in apple fruits. Irrespective of the oviposition date between early June and late August, larval survival in apple fruits was low (0–20.8%). The duration from oviposition to larval emergence from the fruits varied greatly from about 30 d to more than 100 d. When eggs were laid after late June, some larvae remained in the fruits until harvest in late October or early November. The larval survival rate differed significantly depending on whether the fruit was picked from the tree. The survival rate of larvae that entered “unpicked” fruits in early July was only 6.3%. However, 72.1% of larvae successfully emerged from fruits that were picked immediately after larval entry, although these fruits were maintained under the same field conditions as the “unpicked” fruits. Larval emergence from “picked” fruits was more synchronous than that from “unpicked” fruits. These results suggest that low survival and the retardation of larval development are caused by factor(s) related to fruit growth, which remains to be detected.