Annals of Applied Biology ISSN 0003-4746 RESEARCH ARTICLE Transmissibility of Broad bean wilt virus 1 by aphids: influence of virus accumulation in plants, virus genotype and aphid species I. Ferriol 1 , L. Rubio 1 , J. P ´ erez-Panad ´ es 2,3 , E. A. Carbonell 2 , S. Davino 4 & B. Belliure 1,5 1 Instituto Valenciano de Investigaciones Agrarias, Centro de Protecci ´ on Vegetal y Biotecnolog´ ıa, 46113, Moncada, Valencia, Spain 2 Instituto Valenciano de Investigaciones Agrarias, Unidad de Biometr´ ıa e Inform ´ atica, 46113, Moncada, Valencia, Spain 3 Present address: Centro Superior de Investigaci ´ on en Salud P ´ ublica, 46020, Valencia, Spain 4 Department DEMETRA, University of Palermo, 90100, Palermo, Italy 5 Present address: Associated Unit IPAB, CIBIO (UA) – ICA (CSIC), University of Alicante, 03690, San Vicent del Raspeig Alicante, Spain Keywords Plant virus; Secoviridae; Fabavirus; BBWV-1; vectors; virus titre; coat protein sequence. Correspondence B. Belliure, Associated Unit IPAB, CIBIO (UA) – ICA (CSIC), University of Alicante, 03690 San Vicent del Raspeig Alicante, Spain. Email: belen.belliure@ua.es Received: 3 February 2012; revised version accepted: 2 October 2012. doi:10.1111/j.1744-7348.2012.00579.x Abstract Broad bean wilt virus 1 (BBWV-1) is transmitted by several aphid species in a non-persistent manner. Transmission efficiency by vectors is a key factor for understanding virus epidemiology and applying disease control measures based on limiting virus spread. We evaluated the transmission rates of two genetically divergent BBWV-1 isolates (PV-132 from USA and Ben from Spain) infecting broad bean (Vicia faba L.) by isofemale lines of nine aphid species from eight different genera collected in Spain. Our analyses showed that: (a) the virus concentration in the source plant was a key factor in BBWV-1 transmissibility; (b) The Spanish isolate Ben was transmitted more efficiently than the American isolate PV-132 by most aphid species, but this was only due to the higher accumulation of Ben in plants, as both isolates had similar transmissibility after adjusting virus concentration and (c) The transmission rate varied greatly between the different aphid species. Introduction Plant viral diseases are constantly emerging and have serious detrimental consequences for food production and food security (Strange & Scott, 2005; Chakraborty & Newton, 2011). Most plant viruses are spread readily by insect vectors, which have an important effect not only on the epidemiology but also on the evolution of virus populations, which would depend on the transmission efficiency and vector dispersal ability. Therefore, several evolutionary mechanisms can be associated with virus transmission between hosts, such as selection imposed by virus–vector interaction (Power, 2000; Chare & Holmes, 2004) as non-persistent transmission requires specific interactions between virus coat proteins and aphid stylet proteins (Perry et al., 1998; Liu et al., 2002; Moreno et al., 2005; Uzest et al., 2007); genetic drift after population bottlenecks as only few virus particles can be transmitted causing loss of genetic variation (Ali et al., 2006); and differences in migration or gene flow (movement of genes) between separated virus populations (Moya et al., 2004). Broad bean wilt virus 1 (BBWV-1), the member type of the genus Fabavirus of the family Secoviridae (Sanfac ¸on et al., 2009), causes damage to a large range of plant species, including economically important crops such as pepper, spinach, broad bean and ornamental plants (Lisa & Boccardo, 1996). Virions are icosahedral particles composed of two coat proteins and the genome is composed of two single stranded positive sense RNAs encoding a polyprotein which is proteolytically processed into a set of functional proteins. RNA1 encodes proteins involved in genome replication and expression, and RNA2 encodes the movement protein and two coat proteins (Kobayashi et al., 2003; Ferrer et al., 2005). BBWV-1 is transmitted at least by 20 aphid species in a non- persistent manner (Lisa & Boccardo, 1996) and has a worldwide distribution. Studies on BBWV-1 transmission by aphids are scarce, and they have been performed with Ann Appl Biol 162 (2013) 71 – 79  2012 The Authors 71 Annals of Applied Biology  2012 Association of Applied Biologists