Biological control of the box tree moth (Cydalima perspectalis) with a baculovirus

Since several years, box trees (Buxus spp.) are severely affected by the box tree moth, Cydalima perspectalis, which originated from South-East Asia. It rapidly spreads in Europe and can cause complete defoliation of box trees. In laboratory experiments, the effect of the baculovirus Anagrapha falcifera nucleopolyhedrovirus (AnfaNPV) on C. perspectalis was investigated. Two isolates of AnfaNPV, BI-235 and Dn10, were propagated in different larval stages of C.perspectalis and then purified by sucrose density gradient centrifugation. To assess the virulence of AnfaNPV, a bioassay with neonate larvae of C.perspectalis was established. Therefore, suspensions of each virus isolate of varying concentrations were applied to leaf disks of box tree. Mortality was scored after seven days and the median lethal concentrations (LC50) were determined for both isolates using probit analysis. In comparison, the LC50 value for the isolate BI-235 (7.8 x 105 OB/ml) was three times higher than the LC50 value for the isolate Dn10 (2.3 x 106 OB/ml). In addition, the infection of C. perspectalis larvae with AnfaNPV was verified by light and electron microscopic examinations. Both isolates of AnfaNPV infected fat body, epidermis and tracheal matrix of C.perspectalis. These results demonstrated the susceptibility of C.perspectalis to AnfaNPV. In conclusion, AnfaNPV might have the potential of a biological control agent of the box tree moth