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 .