Productivity and quality of polyhedral occlusion bodies of a nucleopolyhedrovirus harvested from Spodoptera litura (Lepidoptera: Noctuidae) larvae

Abstract

We studied the yield and biological activity of polyhedral occlusion bodies (POBs) in a Spodoptera litura multicapsid nucleopolyhedrovirus (SpltMNPV) harvested from larvae of S. litura on different days postexposure to the virus (dpe) by dosing fifth-stadium larvae with the virus. The yield of POBs in live larvae at 5 and 7 dpe was approximately 10 and 40%, respectively, compared to that from cadavers 8 dpe onward. A similar trend was observed in biological activity. POBs in live larvae at 5 dpe were less infectious than those harvested after larval death. The infectivity of POBs in live larvae at 7 dpe was intermediate, but comparable to that of POBs harvested after larval death. The volume of POBs was likely related to differences in biological activity. The volume of POBs harvested at 5 dpe was significantly smaller than that harvested 7 dpe, which was significantly smaller than that harvested after larval death. We discuss the results with respect to the mass production of SpltMNPV in S. litura larvae.