TRANSMISSION OF NEPOVIRUSES BY XIPHINEMA-AMERICANUM GROUP NEMATODES

The transmission of North American nepoviruses by putative species bel onging to the Xiphinema americanum-group is reviewed. Xiphinema americ anum sensu stricto, X. californicum, and X. rivesi each transmit cherr y rasp leaf (CRLV), tobacco ringspot (TobRSV), and tomato ringspot nep ovirus (TomRSV), and X. bricolensis is a vector of TomRSV. The apparen t lack of specificity in the transmission of North American nepoviruse s by X. americanum-group species markedly contrasts with the specific associations between European nepoviruses and their vector nematode sp ecies. Two complementary projects are described examining the taxonomi c identity of putative species in the X. americanum-group, their morph ological and genetic relationships, their ontogeny, and their ability to transmit viruses.