Migration of aphid vectors of Barley Yellow Dwarf in Northeast and Northwest Italy.

The flight activity of aphid species known as vectors of barley yellow dwarf virus (BYDV) was studied in the northwest and the northeast of Italy fYom 1982 to 1986. The winged, migrating forms were captured daily with two Rothamsted Insect Survey suction traps positioned at 12.2 m above ground level, at Cannagnola, near Turin, and at Pozzuolo del Friuii. near Udine. Numbers of individuals captured were compared weekly for Rhopalosiphum padi (L.) (the most fi.equent specfes) and for all vectors together. Weekìy mean temperature and weekìy precipitation were recorded for the two localities. During the last 2 years, data so obtained were used to advise fanners when to sow winter wheat (Triticurn aestivum L.) and barley (Hordeum vulgare L.) in order to avoid the major aphid eights and BYDV infèctions. A good estimate of the total popuìation of autumn migpatin vectors in northern Italy could be obtained by counting R. padi; R. maidis (Fitch)). & insertum (Walker)). Sitobion avenae (Fabricius). Anoecia corni (Fabrlcius), and Myzus persicae (Suìzer).