Detection of DWV by in situ hybridization (A to K) and immuno-histochemistry (L) in queen and drone organs. A, B, D, E, G, J, K, and L: Light microscopy. C, F and H: Laser scanning microscopy (CY5.5 fluorochrome specific signal is in green while autofluorescent background is in red; observed on a Zeiss LSM510 META laser scanning microscope). I: Electron microscopy. A-C: Queen fat body challenged with digoxygenin labeled anti-sense (A) and sense (B) probes and with CY5.5 labeled antisense probe (C). D – F: Drone rectal pads challenged with digoxygenin (D, E) and CY5.5 (F) labeled antisense probes. E and F: detail of a rectal pad (from D). G and H: Drone midgut challenged with digoxygenin (G) and CY5.5 (H) labeled anti-sense probes. I: Electron microscopy analysis of drone midgut content (crude extract). J – L: Drone seminal vesicle challenged with anti-sense probe (J), sense probe (K) and with anti DWV-VP1 polyclonal antiserum (L). Square in J: detail of the signal obtained with digoxygenin labeled anti-sense probes on internal drone seminal vesicle mucosa.