In addition to membrane feeding, virus was directly injected into the hemocoel of the aphid to bypass the HG. For each purified virus preparation, 10 nl of a 20-60 mg/ml virus preparation was injected into an aphid using a Microinjector IM300 (Narishige). Three aphids were placed onto a 7 day old oat seedling (Coast black), 12-16 plants per virus treatment, for a 4 day IAP, after which plants were fumigated to terminate feeding. Plants were evaluated for infection 3-4 weeks later as described above. To test for synergistic effects of EDTA and sodium sulfite treatment on CYDV-RPV transmission by R. padi, we performed a log-linear analysis for a three-way contingency table on the transmission results following microinjection using +/2 EDTA, +/2 sodium sulfite and +/2 transmission as the three variables. Simulations and the experiment were run using the statistical software package JMP (SAS).