Two Naturally Occurring Nuclear Polyhedrosis Virus Variants of Neodiprion sertifer Geoffr. (Hymenoptera; Diprionidae)

Two isolates ofNeodiprion sertifer (Geoffr.) nuclear polyhedrosis virus from Britain and North America were compared using three biochemical techniques. Alkaline protease assays of polyhedra revealed the presence of endogenous enzyme activity in the British isolate but not in the North American isolate. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of virus particle structural polypeptides revealed only minor differences, with the exception that the North American virus was contaminated with polyhedral protein. The restriction endonucleasesSal I,Hind III, andHpa II were used as a definitive method of distinguishing the two variants, with all endonucleases achieving this to a greater or lesser extent. The possible significance of all of these observations is discussed in terms of their possible influence on the registration and field application of this virus.