Infectivity of Epiphyas postvittana nucleopolyhedrovirus for New Zealand leafrollers

Epiphyas postvittana nucleopolyhedrovirus (EppoNPV) was originally isolated from larvae of E. postvittana (Lepidoptera: Tortricidae), which is one of the seven insect species constituting a complex of tortricid insect pests of apples and kiwifruit in New Zealand. Electron microscopy studies confirmed that EppoNPV is a multiply-embedded nucleopolyhedrovirus (MNPV). Host range analysis indicated a broad range of host susceptibility in the leafroller complex. E. postvittana, Planotortrix octo, two populations of Planotortrix excessana, Planotortrix notophaea, Cnephasia jactatana, and Ctenopseustis herana showed varying levels of susceptibility. Only one species, Ctenopseustis obliquana, showed no apparent affects from exposure to EppoMNPV. The LT50 for third instar E. postvittana larvae infected with 106 polyhedral inclusion bodies (PIBs) was 10.8±0.2 days and the LD50 was determined to be 3.8×102 PIBs. LT50 and LD50 values for third instar P. octo larvae, the next most susceptible species, were 13.1±0.8 days and 5×103 PIBs, respectively. Analysis of a region of the polyhedrin gene indicated that the virus used in this study is a single virus isolate.