On the susceptibility of the box tree moth Cydalima perspectalis to Anagrapha falcifera nucleopolyhedrovirus (AnfaNPV)

•AnfaNPV is infective for Diaphania nitidalis and Cydalima perspectalis.•Virus identity was determined by partial sequence of lef-8, lef-9 and polh.•AnfaNPV infections were verified by light and electron microscopy.•Potential of AnfaNPV for the biological control of box tree moth is proposed.

The box tree moth Cydalima perspectalis is an invasive insect pest in many European countries. Caterpillars of this species cause widespread damage on box tree plants. In this study, a new opportunity to control this pest with the baculovirus Anagrapha falcifera nucleopolyhedrovirus (AnfaNPV) was investigated. Initially, AnfaNPV was identified to infect larvae of Diaphania nitidalis by determining the partial nucleotide sequence of the three highly conserved genes polh, lef-8 and lef-9 of the infection causing agent. Two AnfaNPV isolates, termed Dn10 and BI-235, were then propagated in larvae of C. perspectalis and purified by sucrose density centrifugation. A bioassay using leaf disks of box tree was established to evaluate the virulence of both AnfaNPV isolates to neonate C. perspectalis larvae. After 7 days, the mortality of larvae was scored and median lethal concentrations (LC50) were determined to 7.8 × 105 OBs/ml for isolate BI-235 and 2.3 × 106 OBs/ml for isolate Dn10 by using probit analysis. Thus, AnfaNPV BI-235 was significantly more virulent to neonate C. perspectalis larvae than Dn10 based on a three times higher LC50 value. Additionally, light and transmission electron microscopic investigations verified high rates of infection in fat body, epidermis and tracheal matrix of C. perspectalis by both AnfaNPV isolates BI-235 and Dn10. In conclusion, the performed laboratory experiments indicate the susceptibility of C. perspectalis to AnfaNPV.

Graphical abstractLarvae of the box tree moth Cydalima perspectalis (Lepidoptera: Crambidae) are highly susceptible for Anagrapha falcifera nucleopolyhedrovirus (AnfaNPV) as shown by concentration mortality response and the liquefying cadaver releasing a milky occlusion body suspension.Figure optionsDownload full-size imageDownload as PowerPoint slide