Acquisition of Maize Dwarf Mosaic Virus by the Greenbug, Schizaphis graminum1

Abstract

Schizaphis graminum (Rondani), a newly reported vector of maize dwarf mosaic virus, was used to determine the sites of virus acquisition from corn leaf tissues. The greenhug acquired virus during probes as short as 15 seconds. Virus transmission sharply increased with an increase in probe duration to a maximum of 32% at 120 seconds. A gradual decline in acquisition efficiency occurred with probes beyond 120 seconds. Sheath saliva was observed in tissues of virus-infected corn leaves after 20- and 60-second probes by aphids. Stylet penetration of corn leaves during 20-second probes was primarily intercellular and limited to the epidermis. Both epidermal and parenchymal penetration occurred during 60-second probes. The greenbug transmitted virus when stylet penetration was limited to the epidermis. Increase in virus transmission rate by aphids penetrating the parenchyma implicate this tissue as a possible virus source for aphids.