PRELIMINARY STUDY ON THE BIONOMICS AND APPLICATION OF NETTLE CATERPILLAR GRANULOSIS VIRUS CHARACTERIZATION OF INCLUSION BODY PROTEIN OF GRANULOSIS VIRUSES FROM Pieris rapae THE RESTRICTION ENDONUCLEASE ELECTROPHORESIS OF A DNA STRAIN OF PIERIS RAPAE GRANULOSIS VIRUS Evaluation of the effectiveness of PxGV on the population dynamics of Plutella xylostella L Simulation of Plutella xylostella population control by granulosis virus