Identification of virus vectors
A survey of insects collected in leafroll infested mother blocks in the Western Cape indicated that the grapevine leafhopper, Acia lineatifrons (Naudé), was the most likely alternative vector for grapevine leafroll virus disease. It was shown that A. lineatifrons feeds on phloem sap and that leafroll virus Type III can be found in leafhoppers that had fed on leafroll infected grapevines.
Transmission studies conducted with indicator vines (Cabernet franc 213B) exposed to leafhoppers that had previously fed on leafroll infected vines, resulted in one out of 18 test plants testing positive for leafroll virus type III with PCR analysis, 11 months after exposure to leafhopper feeding.
The transmission study needs to be repeated to confirm virus transmission by grapevine leafhoppers. It is recommended that this project be concluded as planned and that further transmission studies be included under project WW 07-14 [Spread of grapevine leafroll-associated virus 3 (GLRaV-3) by scale insects].
Marais, E. 1997. Phloem-feeding by the leafhopper Acia lineatifrons on grapevines (Vitis vinifera) and indigenous blackberry (Rubis chrysocarpus) African Entomology, v. 5 (p. 177-180)