Post-mortem incubation influences occlusion body production in nucleopolyhedrovirus-infected larvae of Spodoptera frugiperda

Publication date: Available online 7 May 2019Source: Biological ControlAuthor(s): Fernando G. Ramírez-Arias, Rodrigo Lasa, Rosa Murillo, Laura Navarro-de-la-Fuente, Gabriel Mercado, Trevor WilliamsAbstractThe efficient production of nucleopolyhedrovirus occlusion bodies (OBs) can limit the commercialization of virus-based insecticides. The production of OBs in SfMNPV-infected Spodoptera frugiperda fourth instars was compared among groups of larvae that were frozen (-20 °C) immediately following death, or subjected to a 9-day period of post-mortem incubation at 5 °C or 15 °C. Incubation at 15 °C resulted in a ∼40% increase in total OB production and OBs per mg larval weight, compared to the -20 °C and 5 °C treatments. OBs from the 5 °C treatment were ∼10% smaller in cross sectional area and small OBs (<1 µm2) were more abundant than in other treatments, possibly due to reduced post-mortem OB maturation in this treatment. SfMNPV genomic DNA in OB samples was 3.6-fold higher in the -20 °C treatment than the 5 °C treatment and 1.7-fold higher than the 15 °C treatment, possibly due to differences in the exposure of viral genomes to degradative enzymes. However, these differences did not affect the concentration-mortality relationship or speed of kill of OBs from the different treatments. The abundance of aerobic microbes increased from ∼3 x 107 CFU/ml in the -20 °C treatment, to approximately 2 x 108 and 3 x 108 CFU/ml in the 5 °C and 15 °C incubation trea...

Source: Biological Control - May 7, 2019 Category: Biology Source Type: research