Fig 7. Cellular immune responses by Spodoptera littoralis larvae as affected by RNAi mediated silencing of the gene Sl gasmin.

The oral administration of Sl gasmin dsRNA induced a significant transcriptional down-regulation of the target gene in the haemocytes of S. littoralis (A). S. littoralis β-actin was used as reporter gene. Gene silencing did not influence nodulation of the Gram-negative bacterium Escherichia coli (B) and of the yeast Saccharomyces cerevisiae (C). Chromatography beads injected into S. littoralis larvae orally treated with Sl gasmin dsRNA were regularly encapsulated and melanized as in controls (D). Conversely, RNAi mediated silencing of Sl gasmin significantly reduced the phagocytic capacity of haemocytes against Gram-negative (E. coli) (E) and Gram-positive (Staphyloccus aureus) (F) bacteria. The values reported are the mean ± S.E. (*P<0.001, Student’s t test). Bars: 15 μm.