All together, viruses account for 47% of emerging infectious diseases (EIDs) of plants [1]. Pathogen introduction is often regarded as the most important driver of plant EIDs, but most plant viruses have a vital dependence on their vectors for their survival and spread. Consequently, a pathogen accidentally introduced into a new area will never become emergent unless the appropriate vectors are present. Viruses transmitted by vectors are significanly much more likely to be designated as emerging threats than are non-vector transmitted viruses [2]. Among vectors,insects are by far the most important, transmitting more than 70% of all known plant viruses [3]. Plant viruses need their insect vectors to become emerging diseases either by increasing their incidence by jumping into a new host or causing severe epidemics in an existing host. From a genetic perspective, vectors impose strong bottlenecks between host-to-host transmissions, during which a large part of the standing variation is lost, thus vectors strongly influence the probability of successful emergence [4]. There are recent examples of emergence and re-emergence of insect-borne plant viruses that threat food security causing instability of food supply. Understanding the causes that drive virus epidemics should provide means to reduce their impact on major crops around the world.

I wish to acknowledge the support, inspiration, and encouragement of colleagues from the International Plant Virus Epidemiology Committee (http://www.isppweb.org/ICPVE) who through their collaboration contributed greatly to the conceptual nature of this paper. Funding for the author of this article was provided mainly by the Spanish Ministry of Science and Innovation, the Spanish Research Council (CSIC) and the European Commission.

5 pgs. - This review comes from a themed issue on Emerging viruses: interspecies transmission Edited by Antoine Gessain and Fernando Garcia-Arenal

Peer reviewed