TEM was also used to detect virus within the aphid. R. padi were allowed a 48 h AAP on membranes containing 40 mg/ml per virus preparation. For each virus preparation, ten aphids were collected after feeding, the head and cauda were removed using a razor blade, and heads and abdomens were fixed for TEM in 1% formaldehyde-2% gluteraldehyde in 0.02 M sodium cacodylate (pH 7.2) containing 10 mM calcium chloride and 0.05% sodium azide for 24 h. Aphids were subsequently prepared for TEM accordingly [13] . The HGs of five aphids were examined per virus treatment. Grids were viewed on a Jeol 1200 transmission electron microscope (TEM) at the Electron Microscope Facility for The Huck Institute of the Life Sciences at The Pennsylvania State University.