Attachment of grapevine flavescence dorée MLO to insect extracts
EPPO Reporting Service 94/027 (1994 No. 2) presented a misleading interpretation of the results of Lefol et al (1993) on interaction between grapevine flavescence dor‚e MLO (EPPO A2 quarantine pest) and various Homoptera. The interactions were studied in an in vitro system, in which the MLO has the possibility to bind to extracts of whole insects or parts of insects, or to cryosections, and is than detected serologically in a so-called 'double blot' system. In such a system, the MLO binds to extracts of Scaphoideus titanus, the known vector of the MLO on Vicia faba test plants. That MLO also binds to several other Homoptera (Psylla pyricola, Ziginidia scutellaris, Muellerianella extrusa and Litemixia pulchripennis) which are not known to be carriers or vectors of the disease and which indeed cannot survive on broad bean or grapevine.
This research has significance especially for better understanding of the specificity of vector ability for MLOs. Ability to bind the MLO (in salivary glands) is probably a necessary condition for vector ability, but it is certainly not a sufficient one.
The four insects cited are perhaps potential vectors of grapevine flavescence dorée MLO to an experimental host yet to be discovered, but they are not potential vectors of the MLO to grapevine.
Lefol, C.; Caudwell, A.; Lherminier, J.; Larrue, J. (1993) Attachment of the flavescence dor‚e pathogen (MLO) to leafhopper vectors and other insects.
Annals of applied Biology 123, 611-622.
EPPO Secretariat, Paris (1994-03)