Transmission of Plant Viruses by Cicadellids

Abstract

Publisher Summary Next to aphids, cicadellids are the most important vectors of plant viruses. The outstanding symptoms produced by cicadellid-transmitted viruses are varied and include necrosis, as in yellow dwarf of potato and phloem necrosis of elm; vein enlargement and leaf curling, as in curly top; tumors, as in wound tumor disease; chlorotic streaking, as in corn streak; wilt, as in the yellow wilt of sugar beets; and scalding or burning of the leaves, as in Pierce's disease of grapes. Transmission of plant viruses by cicadellids is a complicated and subtle process, about which much is yet to be learnt. This chapter indicates that there are probably two major types of transmission by leafhoppers depending on whether the virus multiplies in the vector. At present, the great majority of virus-leafhopper relationships cannot be classified as belonging to either one or the other of these transmission types. Long incubation periods in the vector may be indicative of multiplication and short ones indicative of its absence. There may always be an element of uncertainty about those viruses that the evidence indicates do not multiply in the vector, because such evidence is, of necessity, negative.