Characterization and cross-transmission of baculoviruses infectious to the Diamondback moth, Plutella xylostella, and some other lepidopteran pests of brassica crops

Isolates of a granulovirus (GV) from the Diamondback Moth, Plutella xylostella, and nucleopolyhedrovirus (NPV) isolates from Galleria mellonella and Autographa californica were characterized by restriction endonuclease analysis of viral DNA. The capacity for these viruses to infect P. xylostella larvae and some other lepidopteran pests of brassica crops (including Heliothis virescens, Crocidolomia binotalis and Mamestra brassicae) was examined in cross-transmission experiments in which the DNA isolated from purified progeny viruses, was compared by restriction endonuclease analysis with DNA from the inoculum viruses. Two P. xylostella GV isolates from Taiwan and China (PxGV-Taiwan and PxGV-China) appeared to be very closely-related on the basis of comparative restriction endonuclease analysis of viral genomic DNA. However, both virus isolates could be distinguished by 1-3 major band differences and by sub-molar band variation when their DNA was analysed following digestion with EcoRI, BamHI and HindIII. Both P. xylostella GV isolates proved to be infectious for P. xylostella larvae but did not appear to infect M. brassicae, C. binotalis or H. virescens larvae. In contrast, a G. mellonella NPV (GmNPV) isolate was infectious for P. xylostella larvae as well as for larvae of M. brassicae, C. binotalis and H. virescens. The results also confirmed that P. xylostella larvae are susceptible to infection by A. californica NPV. These studies form the basis for further evaluation of PxGV and GmNPV as potential biological control agents for the Diamondback Moth.