Host range extension of Cydia pomonella granulovirus: adaptation to Oriental Fruit Moth, Grapholita molesta

Among various Cydia pomonella granulovirus (CpGV) isolates, the Mexican isolate (CpGV-M) has demonstrated a significant ability to reduce damage induced by the oriental fruit moth, Grapholita molesta (Busck) (=Cydia molesta) in peach crops. To obtain a more efficient virus for G. molesta control, an experimental virus population was constructed by mixing various CpGV isolates. This mixture was then selected for replication in a G. molesta laboratory colony. After 12 successive passages on this alternative host, the insecticidal efficacy of the virus population had improved. The concentration of virus occlusion bodies required to kill 90 % of neonate larvae was 450-fold lower than that of the original isolate mixture, and 120-fold lower than that of the CpGV-M isolate alone. Following adaptation to this alternative host, the efficacy against its natural host, the codling moth, C. pomonella, was conserved. This mixed isolate population can be produced on C. pomonella without loss of efficacy, which is useful from a commercial production perspective. This adapted virus isolate mixture is likely to prove more effective than individual component isolates at controlling G. molesta.